Electrochemical Energy Storage Device Research Papers

Review on the Chemical Conversion of Carbon Dioxide with Aziridineby Using Catalyts: Environmentally Freiendly Accesses to Cyclic Carbamates

by Meselu Eskezia

2021, Science Journal of Chemistry

Carbon dioxide produced by means of human matters to do is one of the essential contributions accountable for the greenhouse effect, which is enhancing the Earth's climate. From the viewpoint of green chemistry and sustainable... more

In particularly, the catalytic coupling of CO, with energy- rich substrates, such as epoxides and aziridines, to generate polycarbonates/polycarbamates [8]. Among a number of feasible transformations, the atom-economic synthesis of cyclic carbamates from aziridines and CO, has been of terrific interest every industrially and academically. A variety of catalytic structures has been currently developed that efficiently promote the incorporation of this molecule into fee added chemical substances such as quinazoline- 2,4(1H,3H)-diones, azoles, 2-alkynoates, urethanes, and carbonates. Among these transformations, synthesis of 1, 3- oxazinan-2-one derivatives the use of CO, as building. As a part of my continuing critiques on chemical fixation of CO into beneficial products and new methodologies in natural synthesis [9], the usage of aziridine for their transformation into five-member heterocyclic rings such as oxazolidinonesin (Figure 1). In particular, 2-oxazolidinones are found in chiral auxiliaries (with 4-substitution) and in extraordinary antibiotics such as Linezolid and Tedizolid (with 3-aryl,5- alkyl substitution pattern), whereas aryl-fused six-membered rings are current in some HIV-battling antiretrovirals and N- methyl-D-aspartate (NMDA) receptor antagonists [10]. Conventionally, these cyclic carbamates are synthesized the use of phosgene or CO, which are hazardous and environmentally unfriendly, have been avoided, and instead, CO), was once once built-in as Cl beneficial useful resource into cyclic carbamate is formed [11].

normally widespread mechanism for the response of aziridine and carbon dioxide described at Figure 2 [1]. Figure 2. A simplified mechanism of the addition of CO; to aziridines [1].

Figure 3. PEG6ooo (NBu3Br)2-catalyzed fixation of CO? with 2-arylaziridines [19]. lonic liquid catalyzed synthesis of oxazolidin-2-one

Figure 4. Mechanistic proposal for the reaction [20]. (Figure 3). The cycloaddition was once carried out at room temperature for 3-12 h and afforded the favored 5-aryl-2- oxazolidinones 5 in reasonable to nearly quantitative yields. Very recently, Luo and Ji alongside with their co-workers designed and synthesized a novel imidazolium-based ionic liquid functionalized zinc porphyrin (IL-ZnTPP) as one of the most versatile catalysts known for this response [20]. In 2011, Bhanage and colleagues brought a novel polymer supported 1-(2,3-dihydroxylpropyl)-imidazolium bromide (PSDHPIMBr) catalyst for 2-oxazolidinones synthesis from CO) and aziridines under solvent-free condition. The hybrid gadget exhibited a excessive catalytic recreation and reusability for cycloaddition of 1-alkyl-2-arylaziridines 4 with CO, (5 MPa) underneath solvent-free stipulations

corporations in alkyl terminal position, however N-to sylaziridines did not undergo the coupling reaction probably due to the much less nucleophilic exercise of the nitrogen. In addition, the formation of the DBN-CO, was proposed to be the intermediate of the catalytic cycle (Scheme 6) [22]. Figure 5. Synthesis of 2-oxazolidinones from CO, and aziridine catalyzed by DBN [22]. Liu’s group developed an efficient catalytic gadget the use of DBN as organocatalyst and Lil as an additive below atmospheric stress of CO, in toluene to catalyze the coupling of CO, with aziridines giving 2-oxazolidinones (Scheme 5). The system used to be tolerated by means of a quantity of N-alkyl aziridines bearing various useful

Figure 6. Proposed mechanism in the synthesis of 2 -oxazolidinones from CO; and aziridinescatalyzed by DBN [22]

Figure 8. Mechanism that accounts for the formation of 2-oxazolidinones 8 and 9 [21]. Figure 7. L-Histidine-catalyzed cycloaddition of CO; with 1-alkyl-2-arylaziridines 7 [21].

Jiang and co-workers investigated the software of a-amino acids as hydrogen bond donor catalysts for the fixation of CO, onto aziridines. They tested quite a few naturally occurringa-amino acids for the benchmark cycloaddition of CO, (8 MPa) to N-propyl-2-phenylaziridine underneath solvent-free conditions. After optimization, it was observed

Figure 10. The selected free NHCs in the cycloaddition of la and CO; [22]. To compare the catalytic effect between 11 and other NHCs, more free NHCs were selected to catalyze the cycloaddition response of la with CO, in the existing

Table 1. Global nucleophilicity N (eV) for the selected free NHCs and the corresponding activation free energy (kcal mot") in the ring opening steps [23]. Figure 11. Cycloaddition of CO; to several aziridines catalyzed by Nb(OEt);/TBAI [24].

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A Review on Temperature-Dependent Electrochemical Properties, Aging, and Performance of Lithium-Ion Cells

by MOHAMMAD ALIPOUR

2020, Batteries

Temperature heavily affects the behavior of any energy storage chemistries. In particular, lithium-ion batteries (LIBs) play a significant role in almost all storage application fields, including Electric Vehicles (EVs). Therefore, a full... more

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Review of energy and power of supercapacitor using carbon electrodes from fibres of oil palm empty fruit bunches

by Najah Syahirah and

Energy and power capability of supercapacitors are important because of their use in providing backup power or pulse current to electronic/electric products or systems. The choice of the electrode materials, such as... more

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Influence of gamma irradiation exposure on the performance of supercapacitor electrodes made from oil palm empty fruit bunches

by Najah Syahirah

Carbon-monolith electrodes for supercapacitors were prepared from GMs (green monoliths) made from pre-carbonizedfibers of oil palm EFB (empty fruit bunches) and GMs of pre -carbonized EFB fibers exposed to gamma radiation at 5 kGy, 15... more

Fig. 1. FTIR spectra for non-irradiated and y-irradiated GMs at different y-radiation doses. The FTIR spectra in the range of wavenumbers from 400 to 4000 cm™! for GM and y-irradiated GM samples are shown in Fig. 1. The patterns of prominent peaks or bands in Fig. 1 for non- irradiated GMs are typical for lignocellulosic materials and are similar to those in the FTIR spectra reported for EFB [59,60], dried date pits [61] and jute fibers [62]. Assignments of these bands to their corresponding functional groups were reported in Refs. {63—65] for EFB samples, and in general, the bands involved C—O and C—H bonds in the macromolecules found in the EFB. Some differences between the FTIR spectra of the non-irradiated GMs and the precursors in Refs. [63—65] can be detected because the GMs were prepared from pre-carbonized EFB whose hemicellulose was almost fully decomposed, and the lignin and cellulose were partially decomposed during pre-carbonization. Comparison of the FTIR spectra of GM-0 and GM-5 shows that irradiation at 5 kGy can slightly change some of the band intensities, shapes and positions, and also produce new bands. Based on the GM-15 and GM-20 spectra, further increases in the dosage may cause further changes in the spectra. A band at ~2160 cm™! was found to be unaffected by the irradiation. This band is associated with C=C (alkynes) and triple bonds, which are not easily broken by the energy of the irradiation used here [66]. Despite these unchanged bands, the other spectral changes shown in Fig. 1 (GM-O—GM-20)

Fig. 2. XRD pattern for the ACMs from non-irradiated and y-irradiated GMs at different y-radiation dosage.

Fig. 3. FESEM micrographs for (a) ACM-0, (b) ACM-5, (c) ACM-15 and (d) ACM-20 at low magnification (1.00 K x). Fig. 6 shows the Raman spectra of the ACMs, revealing that all exhibited two sharp bands in the 1100—1800 cm™! region and a broad band in the 2400—3200 cm! region; these are typical bands for the activated carbon |74]. The band intensity of the ACMs from irradiated GMs was less than that of non-irradiated GMs. Note that, for structurally higher ordered graphite, only one band appeared, in the 1100-1700 cm! region. The D band at ~1350 cm™! represents disordered carbon, and the G band at ~1580 cm“! represents or- dered (graphitic) carbon | 75]. The degree of ordering or disordering in the samples is represented by the ratio of the intensities of the D FESEM micrographs of the fractured surface of ACM-0, ACM-5, ACM-15 and ACM-20 samples recorded at low magnification (1.00 K x) are shown in Fig. 3(a)—(d), respectively. All of the mi- crographs, which show the rough surfaces of the grains, rough prain boundaries and smooth surfaces, indicate the porous char- acteristics of the samples made of microstructures with a network of open pores. The microstructure shown in Fig. 3(a) is nearly the same as those in Fig. 3(b)—(d), indicating that the y-irradiation applied to the green monolith did not lead to the changes in the ACM (and activated to prepare activated-carbon-monolith) micro- structure on this scale. FESEM micrographs of the fractured surfaces of all of the samples recorded at higher magnification (15 K x) are shown in Fig. 4(a)—(d), respectively. These high magnification mi- crographs show the microporous microstructure of the ACMs with open pores network distributed evenly throughout the samples. The effects of y-irradiation are still not visible in these micrographs at this scale as all of them look nearly identical. It is possible that the differences between the micrograph shown in Fig. 4(a) and the others could only be observed in micrographs produced at much

Fig. 5. Nitrogen adsorption—desorption isotherms for ACMs from non-irradiated anc y-irradiated GMs at different gamma radiation dosage. The EIS data were recorded as Nyquist plots over the frequency range of 107! to 10° Hz for the ACM-based supercapacitor cells, and these plots are shown in Fig. 7(a). The effects of the dosage on the small semicircle (first segment), Warburg diffusion line (second segment) and capacitive line (third segment) can be clearly

Fig. 4. FESEM micrographs for (a) ACM-O, (b) ACM-5, (c) ACM-15 and (d) ACM-20 at higher magnification (15 K x).

Pore characteristic parameter values for ACMs from non-irradiated and y-irradiated GMs. Fig. 6. Raman spectra for ACMs from non-irradiated and y-irradiated GMs at different gamma radiation dosage. Table 2

Fig. 7. (a) Nyquist plot and (b) Specific capacitance vs. frequency for all cell.

Fig. 8. Bode plot for all cells (a) ACM-O, (b) ACM-5, (c) ACM-15 and (d) ACM-20.

Fig. 9. (a) Voltammograms for all of the cells and (b) Specific capacitances at different scan rates for all of the cells. It can also be observed that the voltammograms in Fig. 9(a) do not have any peaks, indicating that the supercapacitive behavior is Fig. 9(b) shows the C,p values at different scan rates for all the ACM cells determined from the voltammogram in Fig. 9(a) using equation (5). All cells exhibit a similar decreasing trend in the Cyp values with increasing scan rate. At very low scan rates, the Csp

Fig. 10. Voltammograms for 1-100 mV s“! for all cells, (a) ACM-O, (b) ACM-5, (c) ACM-15 and (d) ACM-20.

Fig. 11. (a) GCD curves and (b) Ragone plot for all ACMs cells.

Fig. 12. Maximum specific power and maximum specific energy data from different references using (a) aqueous and (b) organic electrolytes.

Interlayer spacing, crystallite dimension, and ratios of L./La and L</doo2 for all ACMs Table 1

The values of Rs, Rp, ESR (EIS), fo, and To for all cells. Table 3

Specific capacitance values from the EIS, CV and GCD methods for all cells. Table 4

The values of ESR (GCD), specific power (P), and specific energy (E) for all cells compared to the values reported in other works (“Present study, Yaqueous electro- lyte, 7organic electrolyte).

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Synthesis and characterization of D-glucose derived nanospheric hard carbon negative electrodes for lithium-and sodium-ion batteries

by Ronald Väli and

The electrochemical performance of glucose-derived hard carbon (GDHC) anode has been evaluated using Li-and Na-salts in ethylene carbonate and propylene carbonate electrolyte mixtures. The LiPF 6 /EC: PC (1:1) system exhibits high... more

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Hybrid energy storage: the merging of battery and supercapacitor chemistries

by Vanesa Ruiz and

2015

The hybrid approach allows for a reinforcing combination of properties of dissimilar components in synergic combinations. From hybrid materials to hybrid devices the approach offers opportunities to tackle much needed improvements in the... more

Fig. 1 Ragone plot with specific energy and power for different energy storage devices. Data from ref. 2.

Fig. 2 Schematic diagram of three types of components used in the design of hybrid materials for energy storage: carbon materials, conduct- ing organic polymers (COPs) and a variety of inorganic electroactive species three of which are just shown as representative examples of extended (oxides, phosphates) or molecular (polyoxometalate) species.

Fig. 3 Black background outlines and ideal geometry with fractal granularity (see text). Inset shows scanning electron micrographs of fractal granularity in LiFePO, materials (O. Ayyad, P. Gomez-Romero, unpublished results).

Fig. 4 Cyclic voltammograms (top) and charge—discharge cycles (bottom) for different types of electrode materials: (a, b), carbon-based double-laye supercapacitors; (c, d) CozO4 pseudocapacitor; (e, f) LiFePO, battery electrode (vs. Li). The series shows the transition from a typical capacitive behavio (EDLC) (a, b) to a typical (two phase) battery electrode (e, f) with a pseudocapacitive oxide electrode as an intermediate case (c, d). It should be noted tha even for the same CozO, material different degrees of capacitive and faradaic components can be appreciated depending on the specific microstructure of the active phase.?° The conception of double-layer supercapacitors led to orders of magnitude improvement in energy density (Fig. 1) by storing A major discovery made along this line by Gogotsi and co-workers involved the demonstration that unsolvated ions can contribute to capacity in purely double-layer electrodes. These researchers used carbide-derived carbons with pore sizes smaller than 1 nm to show that ions diffuse through these ultramicropores upon desolvation and contribute to increased capacitance values.’” It is very interesting to note that this behaviour is indeed reminiscent of ion diffusion in battery materials, where the injection of electrons in a bulk electro- active phase is balanced by the diffusion of naked ions in

Fig. 5 Schematic representations of different possible hybridization approaches between supercapacitor and battery electrodes and materials.

Fig. 6 TEM image of the nanocomposite electrode formed by Li,TisO12 nanoparticles and CNF and specific capacity of the electrode vs. Li anode showing excellent high-rate performance (data from ref. 28).

Fig. 8 Cyclic voltammetry curves of aqueous asymmetric capacitors based on different metal oxides/hydroxides as the positive electrode and reduced graphene oxide as the negative electrode.

Fig. 9 Schematic representation of various chemical synthetic routes used for the synthesis of hybrid electrode materials The fabrication of hybrid nanostructured composite materials involves the hybridization of battery components (oxides, con- ducting polymers or intercalation compounds) and capacitor components (primarily carbons) in a single electrode. Fig. 9 shows a few representative examples of different synthetic routes typically used to prepare this type of hybrid electrode materials. In this way we can simultaneously take advantage (in parallel) of faradaic and capacitive energy storage mechan- isms while improving kinetics and electrochemical performance at high rates. If in addition we make a series combination of capacitive and hybrid electrodes the voltage and energy density of the system will also increase. This approach represents an advanced way to get high power and energy density supercapa- citors by fabricating electrode materials through a rational design of material combination, phase morphology and particle size. More specifically, enhanced electrochemical performance of supercapacitors can be achieved by introducing faradic com- pounds, either extended or molecular into hybrid composite electrode systems based on nanostructured carbons (activated carbons, carbon nanofibers, CNTs, graphene etc.) and wisely building asymmetric combinations of them. Finally, it should be borne in mind that even the more basic studies on this type o hybrid electroactive materials are crucial for a fundamenta understanding of ground aspects such as the interactions between carbons and inorganic materials, the nature of their interfaces or electron transfer processes, all of which in turn wil provide the basis for the improvements of future devices.

Fig. 11 Ragone plot sketching the recent status of supercapacitors, asymmetric supercapacitors with aqueous and organic electrolytes as well as hybrid electrodes with hybrid devices.°°

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Progress in the electrochemical modification of graphene-based materials and their applications

by Muhammad Irfan

2013, Electrochimica Acta

Graphene is a 2D allotrope of carbon with exciting properties such as extremely high electronic conductivity and superior mechanical strength. It has considerable potential for applications in fields such as bio-sensors, electrochemical... more

Fig. 2. Graphene nanomaterials. These can be constrained in a z-axis or in x-y-z axes. z-axis constrained nanomaterials consist of virtually infinite GN sheets with one layer ((A), GN), two layers ((B), double-layer GN), three to ten layers ((C), few-layer GN) and ten to hundred layers ((D), GN platelets). Reproduced with permission from Pumera [18], copyright RSC. This review explores the electrochemical modification of GN flakes to produce high quality composite materials for various applications. Commencing with a brief overview on GN’s his- tory and conventional composite production techniques, a detailed breakdown of six major electrochemical GN modification methods is elaborated upon. The applications of electrochemically modi- fied GN composites are then considered followed by a discussion of potential challenges and opportunities for the technology in future. The major purpose of this review is to stimulate researchers throughout the world to improve the electrochemical process in order to realize the production of high quality composites econom- ically in bulk, and with the least impact upon the ecosystem as possible. Exhibiting unusual physical and electronic properties, as well as excellent charge-carrier mobility, graphene (GN) (Fig. 1) quickly grabbed the attention of physicists and engineers around the world [1,2]. Even though it was well known amongst the scientific com- munity for along time [3,4], its isolation into mono- or multi-layers was considered to be thermodynamically impossible in the past [5]. It was first isolated, however, by means of an elegant “Scotch tape” method almost a decade ago [6] that eventually led to the award of the Nobel Prize in Physics to Geim and Novoselov in 2010 [7]. Since its isolation, GN has seen plenty of applications such as GN-based electronics [8], composite materials [9], molecular gas sensors [10], fuel cells [11] and energy storage and conversion [12-14].

Fig. 3. Timeline for the development of GN using electrochemical techniques (other important historical events related to GN have also been represented).

Fig. 4. (a) Cyclic voltammograms of the electrochemical reduction of GO in 0.1M Na2SO,4 at 50mVs~!, showing the reduction current peak around —0.75V, which first increases and then decreases (to disappear) as the potential cycling proceeds. (b) Schematic diagram of the EPD process and (c) cross-sectional SEM image of the as-deposited electrochemically reduced GO film. Reproduced with permission from RSC [146].

Fig. 5. (a) Schematic illustration and photo for electrochemical exfoliation of graphite. The same apparatus is used to electrochemically reduce GO to produce rGO or GN. (b) Photos of the graphite flakes before and after electrochemical exfoliation. (c) Photo of the dispersed GN sheets in a DMF solution. Reproduced with permission from ACS [151].

Fig. 6. AFM images showing the Au/Cyst/GO monolayer before (a) and after (b) reduction. The height profiles are also shown. Reproduced with permission from ACS [152].

Fig. 7. SEM images of GMH samples obtained after different numbers of cycles during the electrochemical process: (a) 0, (b) 2, (c) 5, and (d) 10 cycles. Reproduced with permission from Springer [156].

Fig. 8. SEM images of GN deposited onto indium tin oxide (ITO) glass using the EPD method at 4V in a 2-electrode cell for: (a) 5s, (b) 10s, (c) 15s, (d) 20s, (e) 25s, (f) 30s. All SEM images were taken at 1300x magnification. Reproduced with permission from Elsevier [162].

Fig. 9. AFM images of an individual GN sheet contacted by two electrodes at various stages: (a) initial bare unmodified layer; ((b), (c)) after electrodeposition of Pd at 0.70 V and 0.85V versus Pt, respectively; ((d), (e)) histograms showing the size distribution of particles for the case of (b) and (c), respectively. (f) Scheme illustrating possible nucleation sites for Pd at defects at the edges of the intact GN islands. Reproduced with permission from Wiley [19].

Fig. 11. (a) Resistance R of a typical GN device as function of the gate voltage Vg. The position of the Dirac point (DP) is indicated. Left inset: structure of the toluene molecule. Right inset: schematic of the device and circuit. (b) Change of the resis- tance as a function of time after adding toluene vapour with no applied gate voltage. Three distinct time intervals are highlighted. Reproduced with permission from Elsevier [175].

Fig. 10. Electrospinning experimental schematic showing stages of jet-to-fibre formation. The apparatus is contained within a ventilated cabinet with access inter- locked to a heat treatment (HT) supply. Both syringe pump and HT supply are software controlled. A closed-circuit camera (not shown) allows magnified observa- tion of the nozzle tip for fine control of the spinning jet. The HT voltage V is applied to the nozzle, the tip of which is at height h above the earthed collection plate. Reproduced with permission from Elsevier [170].

Fig. 12. Scheme of the in situ electrochemical polymerization process of the nanorod-PANI-Graphene composite film. Reproduced with permission from RSC [183].

Graphene is a 2D allotrope of carbon with exciting properties such as extremely high electronic conduc- tivity and superior mechanical strength. It has considerable potential for applications in fields such as bio-sensors, electrochemical energy storage and electronics. In most cases, graphene has been function- alized and modified with other materials to prepare composites. This work reviews the electrochemical modification of graphene. Commencing with a brief history, a summary of several different means of modifying graphene to effect diverse applications is provided. This is followed by a discussion on dif- ferent composite materials that have been prepared with reduced graphene oxide prior to moving onto a detailed consideration of six different methods of electrochemically modifying graphene to prepare composite materials. These methods involve cathodic reduction of graphene oxide, electrophoretic deposition, electro-deposition techniques, electrospinning, electrochemical doping and electrochemi- cal polymerization. Finally a consideration on the applications of electrochemically modified graphene composite materials in various fields is presented prior to discussing some prospects in enhancing the electrochemical process to realize excellent and economic composite materials in bulk.

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Review study of electrochemical impedance spectroscopy and equivalent electrical circuits of conducting polymers on carbon surfaces

by Murat Ateş

Electrochemical impedance spectroscopy (EIS) is an experimental method for characterizing electrochemical systems. This method measures the impedance of the concerned electrochemical system over a range of frequencies, and therefore the... more

Fig. 1. Plots of power density vs. energy density for different growth charges. Cal- culations were based on full weight of the carbon foam/polypyrrole composite electrodes. Current density of polymerisation: 1.5 mA/cm?. Reprinted with permission from Ref. [28]. Copyright @ Elsevier.

Fig. 3. Bode-magnitude plot of P(Py), P(PhPy), and P(MPhPy) electrografted CFME correlated with the calculated data from the theoretical equivalent circuit. Inset R(C(R(Q(RW))))(CR) equivalent circuit model. Reprinted with permission from Ref. [104]. Copyright @ Elsevier. The physical properties of PPy coated over manganese zinc fer- rite (MZF), nickel coated over PPy and PPy coated over Ni-MZF magnetic core particles were investigated. Commercial ferrite and

Fig. 2. SEM of the polypyrrole microstructure (a) on a stainless steel panel and (b) on activated carbon. Polypyrrole/activated carbon composite with (c) 5000 magnification and (d) 1000 magnification. Reprinted with permission from Ref. [102]. Copyright @ Elsevier.

Fig.4. Deposition charge (mC) (Qpg) vs. grain heights (nm) (AFM) and average thicl ness (wm) (SEM). Reprinted with permission from Ref. [104]. Copyright @ Elsevier. Ni-ferrite particles were used primarily, and the PPy-ferrite par- ticles with a composite structure were both synthesized via an oxidative polymerisation of pyrrole in an aqueous solution, which contains well dispersed ferrite particles, and an electrochemi- cal polymerisation technique in ACN. The logf (frequency (Hz)) versus logZ (impedance ({2)) plot were given for the chemically PPy-coated over MZF (1), PPy (2) and PPy-coated over Ni-MZF (3) particles (Fig. 6). The impedance decreases by increasing PPy over Ni-MZF, similar to the conductivity increase by four point probes. No appreciable change in the impedance was observed at frequencies below 103-104Hz, similar to the findings for the films described by Beladakere et al. [106]. The conductivity in this region has always been found to be constant for PPy sys- tems, and interestingly the composite PPy—Ni-MZF also does not

Fig. 5. Nyquist plots of EIS for (a) PPy and (b) Py-THF copolymer. Reprinted with permission from Ref. [105]. Copyright @ Elsevier.

Fig.6. Bode plot of chemically PPy coated MZF (1), PPy (2) and chemically PPy coate 3% Ni/MZF (3). Reprinted with permission from Ref. [107]. Copyright @ Elsevier.

Fig. 7. Bode plot of MZF (1) and electrochemically 3% (2) 8% (3) 10% and (4) PPy coated MZF by using 0.1 M TEATFBO, as an electrolyte in ACN at 10 mA. Reprinted with permission from Ref. [107]. Copyright @ Elsevier. Fig. 7. shows the logf versus logZ plot of MZF (1) and the results of electrochemically PPy-coated MZF particles (3% (2), 8% (3), 10% (4)) by using 0.1 M tetraethyl ammonium tetrafluoroborate (TEATBF,) as an electrolyte in ACN at 10 mA. Yavuz et al. [107] have chosen ACN as a solvent for PPy coated over the ferrite. The results

Fig. 8. Complex-plane plots for RVC/PANI (#4) and CF/PANI electrodes (C) polarized at (a) —0.2 V and (b) 0.2 V (vs. SCE) in a 0.5 mol L~! H3SO4 aqueous solution. Reprinted with permission from Ref. [132]. Copyright @ Elsevier.

Fig. 9. Equivalent circuit for simulating the impedance spectra of the bare carbor electrode (BC) and PC electrodes. C, represents Cg, and Cg) +Cr for the BC and PC electrodes, respectively. Reprinted with permission from Ref. [5]. Copyright @ Elsevier.

Fig. 10. Equivalent-electrical circuit for the Pt/PMOT electrodes. Reprinted with permission from Ref. [164]. Copyright @ Elsevier.

Reprinted with permission from Ref. [132]. Copyright @ Elsevier. Ohmic resistance, charge transfer resistance and capacitance data for RVC/PANI and CF/PANI electrodes obtained from EIS measurements at —0.2 V and 0.2 V (vs. SCE) in a 0.5 mol L-! HSO, aqueous solution.

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One-step hydrothermal synthesis of graphene decorated V2O5 nanobelts for enhanced electrochemical energy storage

by Suresh Kannan Balasingam

Graphene-decorated V2O5 nanobelts (GVNBs) were synthesized via a low-temperature hydrothermal method in a single step. V2O5 nanobelts (VNBs) were formed in the presence of graphene oxide, a mild oxidant, which also enhanced the... more

Figure 1 | Schemes a and b represent the absence of nanobelts formation in case of rGO addition and without carbon material, respectively, via low-temperature hydrothermal synthesis. Scheme c represents the formation of GVNBs by mixing of GO into VO dispersion under the same hydrothermal conditions. mixing of VO suspension and rGO precursors did not induce the formation of nanobelts (Scheme a). However, the mixing of GO precursors with the VO dispersion under the same experimental conditions (scheme c) leads to the formation of GVNBs. In order to confirm the role of GO on the nanobelts formation, only VO dispersion was subjected to the low-temperature hydrothermal pro- cess at identical experimental conditions (scheme b), but no notice- able morphological change could be observed. Figure 2 presents the field-emission scanning electron microscopy (FE-SEM) images of pristine VO, VO after the hydrothermal treatment, the composite of VO with rGO, and GVNBs synthesized via the low-temperature hydrothermal process with different ratios of VO and GO (V3G,, VG, and V,G3, here V3G, indicates the ratio of VO/GO = 3:1). On the basis of FE-SEM images, the transformation into nanobelts have been observed only in case GO was added into the VO suspension, whereas the absence of GO or the use of rGO at the same conditions did not induce the formation of GVNBs. The structure of pristine VO, GVNBs, and rGO have been investigated by X-ray diffraction (XRD), as shown in Figure 3. The peaks of pristine VO well matched the corresponding standard pattern (JCPDS Card No. 89-0612). The XRD patterns of different composites (V3G,, V:Gj, and V,Gs) of GVNBs contain peaks of GO, rGO, and VO nanobelts (VNBs). The peaks at 6.32°, 25.9°, 28.5°, 32.7°, and 41.7° correspond to the (001), (110), (111), (004), and (005) planes of VNBs, respectively*””*. The interlayer distance of GVNBs at the (001) reflection is calculated to be 1.40 nm, which is larger than the interlayer distance of pure V205 nanowires (1.15 nm) reported previously for the same (001) planes”. The peaks at 17.2°, 24.6° are assigned to partially reduced GO and rGO respectively**. Usually, GO is reduced to rGO via a high-temperature heat treatment or by strong reducing agents. In this experiment, partially reduced GO (prGO) was synthesized using he hydrothermal method under identical conditions for all samples o enable a quantitative comparison of the performance*”*. GO shows (001) reflection at the peak position of 10.72° (8.25 A)". When GO is reduced by external factors like a heat treatment or reducing chemical agents, etc., the peak position of the GO sheet shifts toward higher scattering angles, according to the degree of reduction. prGO synthesized by the hydrothermal method shows the (002) reflection at the peak position of 16° (5.54 A). The new peak appeared the (002) plane at 24° (3.71 A) is the characteristic of rGO. Most interestingly, the GVNBs show a very sharp characteristic t t Figure 1 illustrates the role of the different precursors on the syn- thesis of GVNBs by the low-temperature hydrothermal process. The

Figure 3 | XRD spectra of pristine V.O;, composite GVNBs, and rGO measured in the 20 range of 5° to 60°. rGO peak of the (002) plane at 24° (3.71 A) and, simultaneously, the (002) reflection of prGO at the peak position of 17.5° (5.07 A), which confirms that the mixing of V.O5 with GO under the identical hydro- thermal conditions leads to the pronounced reduction of GO to rGO (shift of the (002) peak from 16 to 17.5°)*'***” Figure 4a shows a bright-field transmission electron microscopy (BF-TEM) image of a GVNB with a width of ~200 nm and the corresponding selective area electron diffraction (SAED) pattern. Orthorhombic crystal structure with a lattice parameter of a = 12.30 A,b =3.81 A,c= 13.98 A is confirmed by the indexing of diffraction spots, which are larger than the pure VNBs lattice parameter values (a = 11.722 A, b = 3.570 A, c = 11.520 A)**. The GVNB preferentially grows along the [010] direction. In order to identify the existence of carbon ele- ment inside the GVNBs, we employed scanning transmission elec- tron microscopy (STEM) and electron energy loss spectroscopy (EELS) technique. As shown in EELS, elemental mapping of figure 4c and d, carbon is detected at the whole GVNB region, but the distribution is uneven. Moreover, the point EELS spectrum (see Figure 4e) clearly shows the strong carbon signal at the marked region of figure 4d. The bright contrast of STEM image, strong carbon signal, and increased lattice parameter may be due to the

Figure 2 | SEM images of (a) pristine VO particles, (b) VO after the hydrothermal treatment, (c) VO with rGO after the hydrothermal treatment, anc calcined GVNBs with the following ratios of VO and GO: (d) 3:1 (e), 1:1 (f) 1:3.

Figure 4| (a) BF-TEM image of aGVNB and corresponding SAED (The inset). (b) HAADF-STEM image ofa GVNB and corresponding EELS elemental mapping (c) vanadium and (d) carbon. (e) EELS spectrum acquired at the point of figure (d).

Figure 5 | (a) CV curves of rGO, pristineVO particles, V,G3, V,G;, and V3G, electro-active materials measured at a scan rate of 10 mVs~'in 1 M Na,SO4 solution. (b) CV curves of the V3G; electrode measured at different scan rates ranging from 5 to 125 mV s '. (c) Specific capacitance calculated from the CV curves of Figure 1(b) of the V3G, electrode at various scan rates.

Figure 6 | (a) Galvanostatic charge-discharge curves of rGO, pristine VO particles, V|G3, V;G,, and V3G; electro-active materials measured at a constant current density of 0.5 A g™' in 1 M Na2SO, solution. (b) Galvanostatic charge-discharge curves of VG, electrode material measured at various current densities. (c) Electrochemical impedance spectra of rGO pristine VO; particles, V,;G3, V;G;, and V3G, electro-active materials measured in 1 M NaSO, solution. The inset shows an enhanced view of the high-to-medium frequency region. Further the calculated specific capacitance values of V,G, at various current densities (0.25, 0.5, 0.75 and 1 A g™’) are as follows: 128, 111.9, 105 and 97.5 F g"'. The graphene rich composition V,G3 has specific capacitance values of 121, 117.5, 88.1 and 55 F g™' at the same descending order of current density values. Electrochemical impedance spectroscopy (EIS) is an ideal tool to analyze the internal resistance and capacitance of electrode materials. EIS experiments were carried out in the frequency range of 0.01 Hz to 100 KHz in aqueous 1 M Na,SO, solution. Figure 6 (c) represents the Nyquist plots of rGO, pristine V2Os particles, and three different composites of V,.G, electro-active materials. Each Nyquist plot shows a semicircle at high-to-medium frequencies and an inclined line at low frequency, which represent the charge-transfer and diffusion resistance, respect- ively. In the high-frequency region, the first intersection point with the real axis represents the total impedance of the bulk solution (R,), electrodes (R,), and the contact resistance (R,) between electrode and current collector. At medium frequencies, the second intersection point of the semicircle with the real axis indicates the combination of the double-layer capacitance (C4) inparallel with the charge-trans- fer resistance (R.,). The inclined line in the low-frequency region represents the Warburg impedance (W,) corresponding to the dif- fusive resistance of the electrolyte in the interior part of the electrode surface. The R,, values of VO, rGO, V,G3, V;Gj, and V3G, are 27.5, 20.2, 13.6, 9.2, and 5.7 Q respectively. The charge-transfer resistance of the V,.G, materials is lower than in case of VO and rGO. The lower R,, value of the V,G, materials leads to improved charge transfer and enhanced capacitance due to the following reasons: (i) V2O5 nano- belts having high surface area enhances the pseudocapacitance of the electrode material, (ii) VG, materials possess highly conducting rGO specific capacitance of the electrode materials and the scan rate. By increasing the scan rate, the C, value drops, which is a common phenomenon arising from the mass-transport limitation of sodium ions at high scan rates**. In detail, the interior (bulk part) of the electrode cannot sustain the redox transition due to the diffusion limitation of ions within the electrode. Therefore, the part of the electrode surface is inaccessible for electrochemical reaction at higher scan rates, which leads to a lower capacitance. Figure 6 (a) shows the galvanostatic charge-discharge (CD) curves of rGO, pristine VO part- icles, and the three different VxGy composites obtained using 1 M Na,SO, solution at a current density of 0.5 A g~’. The C, values of the electro-active materials V3G,, V;G,, V,G3, rGO, and VO are 128.8, 111.9, 117.5, 8.2, and 6.3 F g™' respectively. Consistent with the CV curves, the discharge time and the specific capacitance of the VG, materials are higher than those of pristine V,O; particles and rGO sheets. The CD profiles of the V3G, and V,G, composites are sym- metric and resemble an equilateral triangle, which is an indication of a high rate capability during the CD process. The CD curve of the VG; composite deviates from the ideal linear relationship due to the poor conductivity of this material, which further limits its pseudoca- pacitance’’. Figure 6 (b) presents the CD profiles of the V3G, com- posite at various CD rates. All CD curves exhibit a nearly linear CD rate from low to high current densities, which is an indication of balanced faradaic and non-faradaic processes. At very low discharge current density of 0.25 A g™', the pseudocapacitance behavior is clearly visible, reflected in the non-linear shape of the CD curve, and the specific capacitance of 134 F g™' was observed. For higher current densities such as 0.5, 0.75 and 1 A g™', the respective specific capacitance values are calculated as 128.8, 108 and 103.9 F g™’.

Figure 7 | (a) Specific capacitance retention of the V3G, electrode as a function of cycle number, measured by CV at a scan rate of 200 mV s"'in1 M Na,SO, solution. (b) EIS analysis of the V3G, electrode at the initial stage and after 5000 cycles.

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MULTIPHYSICS FINITE – ELEMENT MODELLING OF AN ALL – VANADIUM REDOX FLOW BATTERY FOR STATIONARY ENERGY STORAGE

by Federico Moro

All-Vanadium Redox Flow Batteries (VRFBs) are emerging as a novel technology for stationary energy storage. Numerical models are useful for exploring the potential performance of such devices, optimizing the structure and... more

Figure 1: Schematic diagram of a VRFB (collectors + porous electrodes + polymeric membrane) interfaced to the electrical grid by a DC/AC converter. Electrolytes, stored in separated tanks, are pumped to the VRFB. AEE AEN MM MMe Se MMe Scie che ee Re SM Es el Se RE EM eR eee SAAR, ee Bets enhanced version of this model, with concentration dependent kinetics, was presented in [5]. Starting from this work, a novel 1D steady-state finite-element model of an all-vanadiun redox flow battery is here proposed. A typical VRFB cell (Fig.1) consists of: the positive anc the negative porous layers where chemical half-reactions occur, the separation polyme membrane for proton conduction, and the current collectors which convey the electron: co/from the external circuit. The FEM model incorporates the following multiphysic: aquations: momentum, charge and species conservation, mass transport (Nemst-Plank aquation), electric conduction, charge generation (Butler-V olmer equation) inside the porou: alectrodes, and the proton conduction inside the membrane. In particular, the effect of mas: ransport on the charge generation is taken into account by considering the electrode surface concentrations, which differ from bulk concentrations. Differently from [5], the 1D model i: implemented within a commercial software package (COMSOL) and takes into account the behaviour of the current collectors in order to achieve a more accurate representation of the Jevice. The independent variables of the model are the electrode and electrolyte potential: and the ionic species concentrations in the electrodes. The cell voltage is obtained from the aactrnde notential ac a fiinction of the State of Charade (SoC).

Due to the generality of PDEs defined in the fully coupled model, “General Form PDE” study nodes were used to implement both conduction and advection-diffusion equations in COMSOL. In particular, (8) was implemented as a diffusion-adsorption equation in order to account for the concentration gradient approximation. The degrees of freedom (DoF) of the discrete algebraic system are concentrations cy,4,cys,Cy+ (positive electrode) cyz,cy3,Cy+ (negative electrode), the electrolyte potential @, (membrane and electrodes), and solid phase potential @, (electrodes and collectors). These equations, discretized with quadratic finite elements (for both 1D and 2D) defined on structured meshes, were solved by the Newton- Raphson method with a fixed tolerance of 10~°. The 1D redox flow battery model is constructed from the previous non-linear equations: momentum, charge and species conservation, mass transport (Nerst-Plank equation), electric conduction, charge generation (Butler-V olmer equation) inside the porous electrodes, and the proton conduction inside the membrane. The basic assumption of the model regards the derivation of equation (8), and consists in approximating the concentration gradient inside the porous electrode with a finite difference. The partial differential equations (PDEs) for the 1D model are then simply expressed by substituting the gradient operator with 0, (derivative along the horizontal x-axis in Fig. 2) where electrical conduction and species diffusion occur. The numerical model is implemented in COMSOL®, which provides a robust simulation environment for multiphysics problems. This software, based on the finite element method (FEM) for the discretization of 1D, 2D, 3D PDEs, provides different non-linear solvers. In order to assess the validity and the accuracy of the dimensional reduction numerical

Figure 4: Electrolyte (Je) and electrode (Js) current density in electrode + membrane region.

Figure 6: Negative electrode species concentrations Cy2, Cy3 during charge phase (SoC = 0.5).

Figure 5: Positive electrode species concentrations Cy4, Cys during charge phase (SoC = 0.5). Figure 3: VRFB cell voltage vs. State of Charge.

Figure 7: Reactant concentration cy,, cy; distributions during the charge phase (2D model, SoC = 0.5). Figure 8: Product concentration cy;, cy, distributions during the charge phase (2D model, SoC = 0.5).

lable 2: Physical parameters of the 1D-2D VRFB model

Table 1: Geometrical parameters of the 1D-2D VRFB model

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Enhanced electrochemical performance of cobalt oxide nanocube intercalated reduced graphene oxide for supercapacitor application

by Numan Arshid

We investigated different molar concentrations of cobalt precursor intercalated reduced graphene oxide (rGO) as possible electrode materials for supercapacitors. Cobalt oxide (Co 3 O 4) nanocubes intercalated reduced graphene oxides (rGO)... more

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Synthesis and optical properties of AlCrO3 of small crystallites following a liquid precursor

by Surendra Jangu

Chromium aluminum oxide (AlCrO3) is a promising material for deep-ultraviolet optical masks.1-3 Its moderate band gap and moderate dielectric features are useful for optoelectronics and other applications. To improve the optoelectronic... more

Chromium aluminum oxide (AlCrO3) is a promising material for deep-ultraviolet optical masks.1-3 Its moderate band gap and moderate dielectric features are useful for optoelectronics and other applications. To improve the optoelectronic properties, a liquid precursor assisted sol-gel synthesis method is often used because it provides a precise control over size and morphology of oxides. Considering these points, in this investigation, we report synthesis of AlCrO3 of small crystallites by a soft chemistry involving a hydrogel. A liquid precursor was obtained of Al(NO3)3·9H2O, CrO3 and C6H8O7.H2O dissolved in water by stirring at 60 C for 24 h. After 24 hours of a continuous thermal agitation, the sample has been converted into a dark blue “hydrogel”. A gel so obtained was dried by heating it in air at 120 °C for 8 h. A ceramic powder so obtained was annealed at three different temperatures 500 °C, 700°C and 1000 °C respectively for 30 min each in microwave furnace in order to get a final product AlCrO3 of small crystallites. X-ray diffraction pattern confirms the formation of a phase pure AlCrO3 of a rhombohedral
crystal structure. The microstructure analyzed with SEM images describes small crystallites
which appear in self-assemblies of 200 nm average size. The TGA-DTA analysis of the as-prepared sample depicts a three-step thermal desorption in the range of 50-900 °C, while the DSC thermogram shows two distinct endothermic peaks at 86 °C and 506 °C followed by a weak exothermic peak at 448 °C. Band gaps of the AlCrO3 nanopowders annealed at 500 °C, 700 °C and 1000°C were estimated to be 4.3, 4.6 and 4.7 eV respectively by the light absorption spectra. The optical properties of these samples AlCrO3 confirmed that these can be good light-emitting ceramics, which can be applied in developing verities of optical and gas sensors, color pigments, and optical devices. Keywords: Deep ultra-violet masks, Optical materials, Synthesis, Nanomaterials.
Bibliography
1. E. Kim et al., Jpn. J. Appl. Phys. 39 (2000) 4820.
2. Y. Choi et al., Jpn. J. Appl. Phys. 41 (2002) 5805.
3. J. Kri`an et al., Acta Chim. Slov. 59 (2012) 163.

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α-Na2Ni2Fe(PO4)3: a dual positive/negative electrode material for sodium ion batteries

by ORAYECH Brahim and

A new orthophosphate α-Na 2 Ni 2 Fe(PO 4 ) 3 was synthesized using a solid state reaction route, and its crystal structure was determined from powder X-ray diffraction data. The physical properties of α-Na 2 Ni 2 Fe-(PO 4 ) 3 were studied... more

Fig. 1 Final observed, calculated and difference plots for the XRPD (Cu-K, radiation) refinement of «-NazNi2Fe(PO,)3. The inset corresponds to a zoom of the 20 = 10 to 50° area.

Fig. 2. Projection views of the structure of a-NazNi2Fe(PO.)z along the b-axis (a), and the a-axis (b). In the [(Ni2/Fe2)O,] octahedra the dyiz/re2-0 distances range from 2.007 to 2.054 A with an average distance of 2.0227 A, whereas in the [(Ni1/Fe1)O,] octahedra, the dyii/re1-0 distances range from 2.027 to 2.086 A with an average value of 2.0617 A. Such Ni?'/Fe** coordination and distance values have been

Fig. 3 Coordinations of the sodium atoms in a-Na2NizFe(PO,)s.

Fig. 4 Projections of the structure of B-NazNi,Fe(PO,)z along the c-axis (a), view of the infinite chains of the edge-sharing octahedra (b), and surroundings of the sodium atoms (c, d).

Fig. 5 57Fe Mossbauer experimental and fitted spectra of a-Na2NizFe- (PO,)3 collected at room temperature. The corresponding fitted para- meters are given in Table 4.

Fig. 7. The charge—discharge curves of «-NazNizFe(PO,)z at a current density of 50 mA g™t. The inset corresponds to a zoom of the first dis- charge curve in the capacity area 0 to 60 mAhg™.

Fig. 6 Magnetic susceptibility y vs. temperature and the corresponding 71 vs. T plots of a-NazNi2Fe(PO,)3 measured with the applied field H = 100 Oe.

Fig. 9 Galvanostatic charge/discharge profiles of NazNizFe(PO,)z in an Na-ion cell ata 5 mA g™ current rate in the voltage range 1.8—4.5 V. During the first charge, Na3Ni,Fe(PO,)3 delivers a capacity of 160 mA h g™* in good agreement with the theoretical

Fig. 8 Performance of «-NazNizFe(PO.4)z as a negative electrode in the voltage range 0.03-3 V vs. Na*/Na, at 20 °C.

Table 1 Crystallographic and structure refinement data for a-NazNizFe (POa)3 volume transmission grating, holographic notch filter and thermoelectrically cooled CCD detector (Physics Spectra). The spectrometer was regularly calibrated by using neon lines. A Ti**-sapphire laser pumped by an argon ion laser was tuned at 700 nm. The acquisition time was 60 s.

Table 2 Atomic positions and isotopic displacement parameters for a-NazNizFe(PO,)z from X-ray powder diffraction data at 300 K

“Bond valence sum, B.V. = e”°~”? with the following parameters: b = ) 0.37, To (Na'-O) = 1.803, rp (NiO) = 1.654, ro (Fe''-O) = 1.759, and To (PY-O) = 1.617 A??? Table 3 Interatomic distances (in A) and bond valences (B.V.) for a-NazNizFe(PO,)3. Average distances are given in brackets

Table 4 Fitted °’Fe Mossbauer parameters obtained for the a-Na2Ni2Fe- (PO4)z phase (5 = isomeric shift, 7 = full width at half maximum, and A = quadrupole splitting)

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The Optimization of Microgrids Operation through a Heuristic Energy Management Algorithm

by Bogdan Tomoiaga and

2013, Advanced Engineering Forum 8-9, 185-194

The concept of microgrid was first introduced in 2001 as a solution for reliable integration of distributed generation and for harnessing their multiple advantages. Specific control and energy management systems must be designed for the... more

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Direct growth of nickel cobalt layered double hydroxide on nickel foam via redox reaction between nitrate ion and ethanol for hybrid supercapacitors

by Dr. Debananda Mohapatra

2020, Electrochimica Acta

Binary combinations of transition metal-layered double hydroxides (LDHs) have attracted considerable attention for supercapacitor applications owing to their extraordinary charge storage, low internal resistance , and superior... more

Fig. 3. (a-c) SEM images and (d) TEM image of Ni-Co LDHs on the Ni foam substrate.

Fig. 2. (a) XRD pattern, (b) FTIR spectrum of the Ni-Co LDHs powder, (c-f) full XPS survey spectrum, and high-resolution core spectra of O 1s, Ni 2p, and Co 2p of the Ni-Co LDHs grown on Ni foam.

Fig. 1. Schematic diagram of the structural growth of Ni-Co LDHs on a Ni foam substrate.

Fig. 4. (a) CV curves at different scan rates, (b) peak current density (I) as a function of the square root of the scan rate (v) (lines are for linear fits), (c) GCD curves a different current densities (I), and (d) specific capacity (q) and areal capacity (qq) as a function of the current density (I) for the NF@Ni-Co LDHs electrode.

Fig. 5. (a) Plot of q vs. v-” to find the outer charge of NF@Ni-Co LDHs, (b) Plot of 1/q vs. v’ to find the total charge (qtota!) stored by NF@Ni-Co LDHs, (c) Bar graph of nonfaradaic and faradaic contributions at different scan rates, (d) Variation of Iqig¢/Icap at varying scan rates and potentials.

Fig. 6. (a) Cycling stability and Coulombic efficiency and (b) EIS plots of the NF@Ni-Co LDHs electrode before and after 10,000 charge/discharge cycles.

Fig. 7. (a) Schematic diagram of the Ni-Co LDHs||AC asymmetric device and its (b) CV curves at different voltages from 0 V to 1.6 V.

Fig. 8. (a) CV curves at different scan rates, (b) GCD curves at different current densities, (c) Ragone plot, and (d) cycling stability and Coulombic efficiency of the Ni-Co LDHs||AC. The inset shows the first and 10,000th GCD curves.

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Effects of activation time on the performance of supercapacitor binderless activated carbon electrodes derived from fibers of oil palm empty fruit bunches

by Najah Syahirah

Green monoliths (GMs) with different composition, labelled as GM1, GM2 and GM3, were prepared from self-adhesive carbon grains (SACG) produced from fibers of oil palm empty fruit bunches, SACG treated with 0.4 M H 2SO4 and mixtures of... more

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Electrochemical Production of Sustainable Hydrocarbon Fuels from CO2 Co-electrolysis in Eutectic Molten Melts

by Farooq Sher and

2020, ACS Sustainable Chemistry & Engineering

Because of the heavy reliance of people on limited fossil fuels as energy resources, global warming has increased to severe levels because of huge CO2 emission into the atmosphere. To mitigate this situation, a green method is presented... more

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Progress in the electrochemical modification of graphene-based materials and their applications

by Muhammad Irfan

2013, Electrochimica Acta

Graphene is a 2D allotrope of carbon with exciting properties such as extremely high electronic conductivity and superior mechanical strength. It has considerable potential for applications in fields such as bio-sensors, electrochemical... more

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Cyclic Voltammetry of Metallic Acetylacetonate Salts in Quaternary Ammonium and Phosphonium Based Deep Eutectic Solvents

by Inas AlNashef and

2013, Journal of Solution Chemistry

The electrochemical behaviour of commercially sourced iron (III) acetylacetonate is investigated in six different deep eutectic solvents (DESs) formed by means of hydrogen bonding between ammonium and phosphonium salts with glycerol,... more

Figure 1. Structures of all the salts, the hydrogen bond donors [21] as well as a general representation of a typical metal-based acetylacetonate [9] (not to scale) used in this study are displayed.

Figure 2. CVs at a scan rate of 0.1 V/s using GC working electrode at 35 °C of (i) DES 1; and (ii) 1 mM iron (III) acetylacetonate dissolved in DES 1.

3.4. Quantitative results from CV of iron (III) acetylacetonates. Figure 3. Cyclic voltammetry of the reduction of 1 mM iron (III) acetylacetonate dissolved in DES | at varying scan rates using a glassy carbon working electrode.

Figure A 1 (a). CVs at a scan rate of 0.1 V/s using GC working electrode at 35 °C of (i) DES 1; and (ii) 1 mM chromium (III) acetylacetonate dissolved in DES 1.

Figure A1 (b). CVs at a scan rate of 0.1 V/s using GC working electrode at 35 °C of (i) DES 1; and (ii) 1 mM manganese (II) acetylacetonate dissolved in DES 1.

Figure A 1 (c). CVs ata scan rate of 0.1 V/s using GC working electrode at 35 °C of (i) DES 1; and (ii) 1 mM cobalt (III) acetylacetonate dissolved in DES 1.

Figure A1 (d). CVs ata scan rate of 0.1 V/s using GC working electrode at 35 °C of (i) DES 1; and (ii) 1 mM copper (II) acetylacetonate dissolved in DES 1.

Figure A 1 (e). CVs ata scan rate of 0.1 V/s using GC working electrode at 35 °C of (i) DES 1; and (ii) 1 mM nickel (II) acetylacetonate dissolved in DES 1.

Figure A2 (a). CVs at ascan rate of 0.1 V/s using GC working electrode at 50 °C of (i) DES 2; and (ii) 1 mM cobalt (III) acetylacetonate dissolved in DES 2.

Figure A2 (b). CVs at a scan rate of 0.1 V/s using GC working electrode at 50 °C of (i) DES 2; and (ii) 1 mM copper (II) acetylacetonate dissolved in DES 2.

Figure A 2 (c). CVs ata scan rate of 0.1 V/s using GC working electrode at 50 °C of (i) DES 2; and (ii) 1 mM nickel (II) acetylacetonate dissolved in DES 2.

Figure A 2 (e). CVs ata scan rate of 0.1 V/s using GC working electrode at 50 °C of (i) DES 2; and (ii) 1 mM zinc acetylacetonate dissolved in DES 2.

Figure A 2 (f). CVs at ascan rate of 0.1 V/s using GC working electrode at 50 °C of (i) DES 2; and (ii) 1 mM manganese (II) acetylacetonate dissolved in DES 2.

Figure A3 (a). CVs at ascan rate of 0.1 V/s using GC working electrode at 50 °C of (i) DES 3; and (ii) 1 mM chromium (III) acetylacetonate dissolved in DES 3.

Figure A3 (b). CVs ata scan rate of 0.1 V/s using GC working electrode at 50 °C of (i) DES 3; and (ii) 1 mM cobalt (III) acetylacetonate dissolved in DES 3.

Figure A3 (c). CVs ata scan rate of 0.1 V/s using GC working electrode at 50 °C of (i) DES 3; anc (ii) 1 mM copper (II) acetylacetonate dissolved in DES 3.

Figure A3 (d). CVs ata scan rate of 0.1 V/s using GC working electrode at 50 °C of (i) DES 3; and (ii) 1 mM nickel (II) acetylacetonate dissolved in DES 3.

Figure A3 (e). CVs ata scan rate of 0.1 V/s using GC working electrode at 50 °C of (i) DES 3; and (ii) 1 mM iron (ID) acetylacetonate dissolved in DES 3.

Figure A3 (f). CVs ata scan rate of 0.1 V/s using GC working electrode at 50 °C of (i) DES 3; and (ii) 1 mM zinc acetylacetonate dissolved in DES 3.

Figure A3 (g). CVs at ascan rate of 0.1 V/s using GC working electrode at 50 °C of (i) DES 3; and (ii) 1 mM manganese (II) acetylacetonate dissolved in DES 3.

Figure A4 (a). CVs at ascan rate of 0.1 V/s using GC working electrode at 35 °C of (i) DES 4; an (ii) 1 mM cobalt (III) acetylacetonate dissolved in DES 4.

Figure A4 (b). CVs at a scan rate of 0.1 V/s using GC working electrode at 35 °C of (i) DES 4; and (ii) 1 mM zinc acetylacetonate dissolved in DES 4.

Figure A5 (a). CVs at ascan rate of 0.1 V/s using GC working electrode at 35 °C of (i) DES 5; and (ii) 1 mM nickel (II) acetylacetonate dissolved in DES 5.

Figure A5 (c). CVs ata scan rate of 0.1 V/s using GC working electrode at 35 °C of (i) DES 5; anc (ii) 1 mM zinc acetylacetonate dissolved in DES 5.

Figure A5 (d). CVs ata scan rate of 0.1 V/s using GC working electrode at 35 °C of (i) DES 5; and (ii) 1 mM manganese (II) acetylacetonate dissolved in DES 5.

DESs from glycerol and tri-ethylene glycol were synthesised and used. The chemical structures of the salts and hydrogen bond donors are illustrated below (Figure 1) [21]. The chemical structure of a metal-based acetylacetonate salt (the metal atom is denoted as M) is also given in Figure 1 [9]. The molar ratio for synthesising the DESs and their physical properties are detailed in an earlier investigation [21] while their respective abbreviations are shown in Table 2. chromium, cobalt, man 99% purity) were emp sieves 4A in order to re The components for preparing the DESs were sou Merck (N,N-diethylenethanol ammonium c ganese, copper, nickel (Merck, sy move traces of moisture. rced from Sigma- hloride, synthesis grade). T nthesis grade) iro trogen with less Aldrich (> 99% purity) and he acetylacetonate salts of n and zinc (Sigma-Aldrich, oyed as received. Molecular sieves 4A were also supplied by Sigma-Aldrich for the purposes of drying the electrolytes. Ultra-pure ni provided by BOC (Gui than 1 ppm of oxygen was Idford, Surrey, U.K.) and was passed through a column containing molecular

Table 3. Solubilities of seven acetylacetonate salts in six different DESs prepared as per recommendations in the literature [21,23,25].

Table 4. Cyclic voltammetric data for oxidation of ferrocene in DESs half wave potential) estimated from (Epa + Ep,)/2 (the ave ANS Important quantitative data acquired from CVs of DESs such as values of the E12 (reversible AEp= Epa — Epc (the peak—to—peak potential separation), i cathodi c peak current) and Wj). (the peak width at half-h rage of anodic and cathodic peak potentials), pai pc (anodic peak current divided by eight) for both oxidation and reductior processes [21], are shown in Table 4. For all investigated DESs, the cathodic and anodic peak currents TEVETSE from th increased with magnifying scan rate and ipa/ip-=1.0 (i.e., the separati reversible, one-electron transfer would principally have a AZ, = 0.059 V at 298 K. The difference scans was close to unity) and remained oblivious to the scan rate. The peak potential on (4E,) from CVs conducted at distinctive scan ra ratio of peak currents for the forward anc tes was approximately 0.07 V. A rapid, is ideal value at increasing concentrations and scan ra tes in the tested DESs was ascribed to the occurrence of uncompensated solution resistance [34,35]. In addition it was observed that for different scan Ta tes the E12 and W1/2 remained constant.

Table 5. Concentration-dependent diffusion coefficients of Fe(acac)3; in DESs as well as their rate constants In consideration of the above scenario, an assumption about the electrochemical reversibility of ‘Fe(acac)3]/[Fe(acac)3]* at the respective scan rates was made in order to calculate the diffusion coefficients of Fe(acac)3 and Fe(acac)3* in the DESs. The peak current was found to vary in a linear manner in response to the square root of the scan rate on glassy carbon electrodes (Figure 4). This confirmed that the process was mainly regulated by the diffusion of [Fe(acac)3]/[Fe(acac)3]* in DES 2 (plots of other DESs are not shown).

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Facile electrochemical synthesis of few layered graphene from discharged battery electrode and its application for energy storage

by Santosh Tiwari

A cost-effective, simple and non-hazardous route for synthesis of few-layered graphene from waste zinc carbon battery (ZCB) electrodes via electrochemical expansion (ECE) has been reported. In this synthesis, we have electrochemically... more

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Nanotechnological Applications in Nickel Metal Hydride Battery

by myrat durdakow

In this specific paper, firstly Ni Nickel Metal Hydride Battery is explained, than nanotechnological applications on it is reviewed.

materials. With the new nanotechnological findings it can be easily achieved. [1, 2

KOH. In figure 2, representation of a NiMH battery is given below. [1, 2] 1.1 Chemistry of NiMH Battery

Figure 3: Schematic represantation of elecrodes of sealed Ni-MH battery [2] active material in negative electrode as in figure 3.

Figure 4: Schematic representation of a phase and B phase [1] In an initial state « phase is forming interstitially. As known, the hydrogen has the smallest atomic size.

Figure 5: Schematic representation of PCI curves (a) and the van’t Hoff plot (b) [1] Commercially, there are two different types of alloys used as anode materials in Ni-MH batteries. They are ABs and ABzalloys. The ABs class of alloys are based on the rare — earth (Misch metals) metals, for example LaNis. The AB2 class of alloys consist of zirconium and titanium. In order to improve performance of alloys, some of the base metals are replaced by other metals. Also, AB2 type of alloys has higher capacity per unit weight and volume, the AB; class of alloy dominates in Ni — MH batteries because of overall advantages, including high discharge rate, high rate charge acceptance, low and high dicnharnao tamnaratinac and cinannr high tamnoaratinm arncnantanrcro [1 91]

At the normal discharge rate (1 C) a little better performance is observed by adding CNT. However, the effect of CNT’s on cycling stability is better absorbed in high discharge rates (10 C). So it can be concluded that the addition of CNT’s into the positive electrode increases cycling stability of battery in positive manner. During charge — discharge cycles when battery were at 100% DOD state, the internal resistance can be measured. The results can be seen in figure 7. The resistivity of the cathode is due to nature of the active material. The addition of highly conductive CNT’s somehow improve the property of the active material. Furthermore, nanostructure of the CNT provide excess electrochemical reaction surface of the active particle and reduced the evolving of O2. As a result, the internal resistivity of the batteries with various CNT content can be seen in figure 6. resistance can be measured. The results can be seen in figure 7. The resistivity of the cathode is due to

Figure 7: Variation of the internal resistance of batteries [3]

Figure 8: High rate capability of batteries at different CNT content [3] high rate capability of the batteries with CNT’s and without CNT’s can be absorbed in figure 8.

Figure 9: 2C rate discharge characteristics with respects to cell voltage and the negative aT nT a ee ee eT and the negative electrode potential is shown figure 9. [4] electrode potential [4] From the graph above it can be said that the cell with palladium nanotube has higher discharge voltage and higher electrode potential than standard alloy anode electrode. For the cut —off 1.0 V the nanotube - containing electrode shows 32% higher capacity than standard cell. The effect of Pd nanotube is more obvious at high rate. At 4C rate and for a cut — off 0.9 V the nanotube containing electrode has 45% higher capacity than that of standard alloy electrode. This can be absorbed in figure 10. As a result, the cell performance is improved significantly by incorporating palladium nanotube in the anode electrode. [A] From the graph above it can be said that the cell with palladium nanotube has higher discharge voltage yf the electrode. As a solution nanostructured Pd is synthesized and added to the electrode material

Figure 10: 4C rate discharge characteristics with respects to cell voltage and the negative Conclusion bad characteristics of the battery can be improved by the help of foundations of nanotechnology. References

Table 1 Comparison between Ni- MH and Li-ion sealed cells. [1, 2]

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Polyaniline integration and interrogation on carbon nano-onions empowered supercapacitors

by Dr. Debananda Mohapatra

2021, Electrochimica Acta

The clean energy storage and fast delivery during the demand for sudden power applications encourage us to synthesize highly graphitic carbon nano-onions (CNOs) using a simple, one-step synthesis protocol. The as-synthesized CNOs... more

Fig. 1. Schematic diagram demonstrates the synthesis of CNO and the PANI/CNO heterostructures by in-situ oxidative polymerization of aniline monomer.

‘ig. 2. (A) XRD patterns, (B) FTIR spectra, (C) TGA thermograms, (D) BET isotherms, and BJH pores size distribution (inset) of the as-synthesized CNO, PANI, PANI/CNC *lectrode materials.

Fig. 3. (A) XPS full survey scan, high-resolution XPS core spectra for (B) C 1s, (C) N 1s, and (D) O 1s electronic states for PANI/CNO heterostructure

Fig. 4. FE-SEM images showing acquired morphology for (A) pristine PANI, (B) pristine CNO nanoparticles, (C and D) PANI/CNO heterostructure

Fig. 5. (A and B) TEM micrographs for pristine PANI, (C) SAED pattern for pristine PANI, (D and E) TEM and HR-TEM micrographs for CNO nanoparticles, (F) SAED patter for CNO nanoparticles, (G and H) TEM micrographs for PANI/CNO heterostructure, and (I) SAED pattern for PANI/CNO heterostructure.

Fig. 6. (A) CV curves for CNO, (B) CV curves for PANI/CNO heterostructure, (C) comparative CV curves, (D) GCD curves for CNO, (E) GCD curves for PANI/CNO heterostructure, (F) comparative GCD curves. Table 1

Fig. 7. 3D plot showing the specific capacitance obtained at the various current densities for the as-synthesized electrode materials.

Fig. 8. Energy density vs. power density bar plot at the current density of (A) 1 A g~', (B) 10 A g~', (C) comparative Ragone plots, (D) Coulombic efficiencies at various current densities, (E) EIS plots, and (F) magnified EIS plot at the higher frequency region.

Comparative table enlisting specific capacitance of various carbon nano onion and polyaniline based supercapacitive electrode materials

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Cyclic Voltammetry of Iron (III) Acetylacetonate in Quaternary Ammonium and Phosphonium Based Deep Eutectic Solvents

by Laleh Bahadori

2013

The electrochemical behaviour of commercially sourced iron (III) acetylacetonate is investigated in six different deep eutectic solvents (DESs) formed by means of hydrogen bonding between ammonium and phosphonium salts with glycerol,... more

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Few-layered MoSe2 nanosheets as an advanced electrode material for supercapacitors

by Suresh Kannan Balasingam

We report the synthesis of few-layered MoSe2 nanosheets using a facile hydrothermal method and their electrochemical charge storage behavior. A systematic study of the structure and morphology of the as-synthesized MoSe2 nanosheets was... more

Raman spectroscopy was employed to further study the structure of the as-synthesized MoSe, nanosheets. The typical peaks of MoSe, nanosheets at 239 cm™* and 287.11 cm“ are observed in the spectra (Fig. 2), which corresponds to the out- of-plane A,, mode and in-plane Ez," mode of MoSe, respect- ively.** For bulk MoSez, the Ai. mode appears at 242 cm™'.

The surface morphology of the as-synthesized MoSe, was investigated using HR-TEM. Fig. 4 presents HR-TEM images of the as-synthesized MoSe, nanostructure. The low-magnifi- cation TEM images (Fig. 4a and b) show MoSe, nanosheets. Fig. 4c provides clear evidence of the formation of few-layered

Fig. 2 Raman spectrum of MoSez nanosheets showing two distinct Ax, and E2,' Raman modes. Fig. 1 XRD spectrum of MoSez nanosheets.

Fig. 3. (a) High resolution XPS spectra of Mo 3d, (b) Se 3d regions of MoSez nanosheets.

Fig. 4 TEM images of MoSez nanosheets: (a) and (b) low magnification, and (c) high magnification; the inset shows the FFT pattern.

Fig. 5 (a) Cyclic voltammograms of MoSez nanosheets in 0.5 M H2SO,4 electrolyte measured at different scan rates ranging from 2 to 125 mV s~. (b) Specific capacitance value calculated from the CV curves of (a) at different scan rates. The MoSe,-nanosheet-coated stainless steel substrates were assembled in a two-e lectrode configuration (a symmetric cell in a parallel-plate geometry, which is typically used in super- capacitor measureme nts), with Whatman filter paper as the separator and 0.5 M sulfuric acid as the electrolyte. The elec- trochemical behavior of the MoSe, electrodes was character- ized using CV, EIS, and CD cycling measurements. Fig. 5a shows the typical CV curves of a symmetric device (MoSez nanosheets coated on a stainless steel substrate as working and counter electrod es) at various scan rates (2 mV s+ to 125 mV s_‘). All the CV curves retain their nearly rectangular shape at the various scan rates, which confirms the ideal EDLC behavior (non-faradaic process, as indicated in eqn (4)) of this material wit h excellent reversibility. Moreover, the broad peak appearing in both the anodic and cathodic scans indicates the redox be from the faradaic elec havior of the MoSe, nanosheets resulting trochemical process, as shown in eqn (5).

Fig. 6 (a) Cyclic voltammograms of MoSe2 nanosheets in 0.5 M H2SO,4 electrolyte measured at different scan rates ranging from 2 to 125 mV s~1. (b) Specific capacitance value calculated from the CV curves of Fig. 5a at different scan rates.

Fig. 7 (a) Specific capacitance retention of the MoSez nanosheets as a function of cycle number, measured by charge-—discharge at a high current density of 5 A g™t in 0.5 M H2SO, electrolyte. (b) Electrochemical impedance spectra of a symmetric device recorded at the initial stage and after 10 000 cycles. The inset shows an enhanced view of the high- to-medium frequency region.

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Carbonate decomposition: Low-overpotential Li-CO 2 battery based on interlayer-confined monodisperse catalyst

by Shumao Xu

2018, Energy Storage Materials

Keywords: Layered double oxides confined single atoms interlayered confinement Li-CO 2 battery low overpotential A B S T R A C T The operation of Li-air batteries is currently limited to O 2 instead of air, mainly attributed to the... more

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Electronic Effects of Substituents on Redox Shuttles for Overcharge Protection of Li-ion Batteries

by mehmet cem ates

2012, Journal of the Electrochemical Society

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A method to produce binderless supercapacitor electrode monoliths from biomass carbon and carbon nanotubes

by najah syahirah

2014, Materials Research Bulletin

Binderless supercapacitor electrode monoliths (BSEM), prepared via the carbonization and activation of green monoliths from (a) self-adhesive carbon grains (SACG) from oil palm empty fruit bunch fibers, (b) SACG mixed with KOH, and (c)... more

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Tailoring the pseudocapacitive behavior of electrochemically deposited manganese-nickel oxide films

by Antonello Vicenzo

A B S T R A C T Manganese-nickel mixed oxide thin films were deposited by anodic electrodeposition on stainless steel substrate from an acetate solution using a potentiodynamic technique, at scan rate of 100 mV s À1 and room temperature.... more

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Nanosized Mn Ni oxide thin films

by Antonello Vicenzo

A B S T R A C T The present study addresses the synthesis of manganese-nickel oxide thin films via potentiodynamic anodic electrodeposition as supercapacitor electrodes. We study in particular the effect of the deposition scan rate and of... more

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Fabrication and electrochemical performance of nickel ferrite nanoparticles as anode material in lithium ion batteries

by G. Caboche and

2007, Electrochemistry Communications

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A New Approach towards Improving the Specific Energy and Specific Power of a Carbon-Based Supercapacitor using Platinum-Nanoparticles on Etched Stainless Steel Current Collector

by Najah Syahirah

We report an improved performance of a carbon-based supercapacitor using etched stainless steel (SS) current collector deposited with platinum nanoparticles (PtNs) over bare SS current collector/un-etched SS current collector deposited... more

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Hybrid energy storage: the merging of battery and supercapacitor chemistries

by Vanesa Ruiz

2015, Chem. Soc. Rev.

The integration of capacitive and faradaic energy storage mechanism in the form of hybrid materials, electrodes and devices aims at increasing energy and power densities for the next generation of electrochemical energy storage devices.

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Electrochemical impedance spectroscopy study of supercapacitors using deposited nickel oxide nanoparticles carbon monolith electrodes

by Najah Syahirah

Activated carbon monolith porous electrodes of a supercapacitor prepared by carbonization (N 2) and activation (CO 2 ) methods from KOH-treated pre-carbonized biomass fibers were deposited with nickel oxide at varying dipping time (from... more

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Hybrid energy storage: the merging of battery and supercapacitor chemistries

by vanesa ruiz

2015

The hybrid approach allows for a reinforcing combination of properties of dissimilar components in synergic combinations. From hybrid materials to hybrid devices the approach offers opportunities to tackle much needed improvements in the... more

Figure 1 Ragone plot with Specific Energy and Power for different energy storage devices. Data from just complementary of typical batteries (Figure 1). to high currents and high specific power but to poor specific energy, a performance

and to increase energy densities of conventional supercapacitors. Figure 2 Schematic diagram of three types of components used in the design of hybrid materials for

Figure 3 Black background outlines and ideal geometry with fractal granularity (see text). Inset shows Scanning Electron Micrographs of fractal granularity in LiFePO, materials (O. Ayyad, P. Gomez- Romero, unpublished results). should provide a combination of high energy and power for a given active materia

Figure 4 Cyclic voltammograms (top) and charge-discharge cycles (bottom) for different types of electrode materials: (a, b), Carbon-based double-layer supercapacitors. (c, d) Co304 pseudocapacitor. (e, f) LiFePO, battery electrode (vs. Li). The series shows the transition from a typical capacitive behavior (EDLC) (a, b) to a typical (two phase) battery electrode (c, d) with a pseudocapacitive oxide electrode as an intermediate case (e, f). It should be noted that even for the same Co30, material different degrees of capacitive and faradaic components can be appreciated depending on the specific microstructure of the active phase.”°

Hybrid material: battery-type and capacitor type materials combined in a hybrid electrode Figure 5 Schematic representations of different possible hybridization approaches between

Figure 6 TEM image of the nanocomposite electrode formed by Li,gTis0,2 nanoparticles and CNF and (center).7° specific capacity of the electrode vs. Li anode showing excellent high-rate performance (Data from ref they were, in turn, applying the double hybridization approach shown in Figure 5

Figure 8 Cyclic voltammetry curves of aqueous asymmetric capacitors based on different metal oxides/hydroxides as positive electrode and reduced graphene oxide as negative electrode.

Figure 9 Schematic representation of various chemical synthetic routes used for the synthesis of

Figure 11 Ragone plot sketching the recent status of supercapacitors, asymmetric supercapacitors with aqueous and organic electrolytes as well as hybrid electrodes with hybrid devices.*° Also 3D network structure is beneficial to enhance the electron transport while

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Redox-additive electrolyteedriven enhancement of the electrochemical energy storage performance of asymmetric Co 3 O 4 // carbon nano-onions supercapacitors

by Dr. Debananda Mohapatra

2021, Energy

For efficient energy storage, Co 3 O 4 @nickel foam exhibiting a plate-like (p-Co 3 O 4) and grass-like (g-Co 3 O 4) nanostructure were prepared as binder-free supercapacitor electrode materials. The electrochemical performance of the... more

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Journal of The Electrochemical Society Practical Development of a ZnBr2 Flow Battery with a Fluidized Bed Anode Zinc-Electrode

by Ibitoye Adelusi

The penetration of renewable sources (solar and wind power) into the power system network has been increasing in the recent years. As a result of this, there have been serious concerns over reliable and satisfactory operation of the power... more

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Multistaged discharge constructing heterostructure with enhanced solid-solution behavior for long-life lithium-oxygen batteries

by Shumao Xu

2019, NATURE COMMUNICATIONS

Inferior charge transport in insulating and bulk discharge products is one of the main factors resulting in poor cycling stability of lithium-oxygen batteries with high overpotential and large capacity decay. Here we report a two-step... more

Fig. 1 Synthesis and analysis of the cathode catalysts. a Schemes for synthesis and the structure of PVP-C@LDO. b X-ray diffraction (XRD) patterns of CoFe LDH and PVP-C@LDO. ¢, d Scanning electron microscopic (SEM) image of PVP-C@LDO. Scale bars, 100 and 5 pm. Inset in d with scale bar of 1 pm. e, f Transmission electron microscopic (TEM) and high-resolution TEM (HRTEM) images of PVP-C@LDO. Scale bars, 500 and 2 nm. g Elemental mapping images of PVP-C@LDO. Scale bar, 1 pm.

Fig. 2 Electrochemical performance. a, b PVP-C@LDO and CoFe LDO-based conventional Li-O> battery. ¢, d Multistaged pretreatment of PVP-C@L and CoFe LDO cathodes. Stage I: PVP-C@LDO/CoFe LDO|0.8 M KPF¢-EC: DEC (1:1)|K. Stage Il: PYVP-C@LDO/CoFe LDO|1M LiTFSI-TEGDME|Li. e, Cycling performance of PVP-C@LDO and CoFe LDO after multistaged discharge. Current densities are 100 mAg7!. g, h Nyquist plots and cyclic voltammetric (CV) curves of PVP-C@LDO before and after discharge at a stage | and stage II. i Schematic representation of the formation of film-like _,O2 after multistaged discharge.

Fig. 3 Multistaged discharge products. a, b N 1s and O 1s X-ray photoelectron spectroscopy (XPS) spectra of initial PYP-C@LDO and discharged PVP- C@LDO at stage | and stage Il. ¢, d XRD patterns and Fourier transform infrared spectra of initial PVP-C@LDO and discharged PVP-C@LDO at stage | and stage Il.

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Fabrication of Titanium Dioxide Nanofiber Composite and Using in Modified Carbon Paste Electrode for Determination of Tryptophan in the Presence of Penicillamine and Folic acid

by rezvan arazi

2016

In this present work, we prepared a carbon paste modified electrode with 9,10-dihydroxy-7-methoxy-6H-benzofuro[3,2-c]chromen-6-one (DMC) and titanium dioxide nanofiber composite (DMC/NF/CP) as a electrochemical sensor for... more

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Electrochemical Kinetics of SEI Growth on Carbon Black: Part I. Experiments

by Martin Bazant

Journal of The Electrochemical Society

Growth of the solid electrolyte interphase (SEI) is a primary driver of capacity fade in lithium-ion batteries. Despite its importance to this device and intense research interest, the fundamental mechanisms underpinning SEI growth remain... more

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Enhancing the stability of electrochemical asymmetric supercapacitor by incorporating thiophene-pyrrole copolymer with nickel sulfide/nickel hydroxide composite

by Anish Nath and

2022, Journal of Energy Storage

The practical application of a supercapacitor predominantly relies on its sustained cyclic stability. Hence it is essential to develop materials with high stability for the efficient supercapacitor applications. Herein, we demonstrate the... more

Fig. 1. SEM images of (A) NSH (B) copolymer (cPPyTh) and NCP with (C,D) lower & higher magnifications. To understand the molecular nature of the composite vibrational spectroscopy analysis has been performed. Individual peak analyses of Fig. 4(A) shows the Raman spectrum of NCP. The broadness of the peaks indicates the amorphous nature of the material. The peaks at 144 cm", 185 cm~/, 222 cm", 285 cm", 310 cm", 345 cm! can be attributed to the vibration modes of rhombohedral Ni3S2 / NiS [27,28].

Fig. 2. TEM images of (A,B) NSH and (C,D) NCP composites.

Fig. 3. FTIR spectra of NCP along with NSH and cPPyTh (A) 4000 cm! to 400 cm™! and (B) showing the low wavenumber region 1800 cm! to 400 em™! (C) XRD spectra of NCP, NSH and cPPyTh (PDF2 database: Ni(OH)2 (# 00-038-0715), NisS2 (#01-073-0698) and NiS (#03-065-3687)).

Fig. 4. Raman spectrum of NCP composite (A) spectral region from 100 to 2000 cm~! (B) spectral region 100 to 610 cm".

Fig. 5. XPS spectra showing the wide scan (A), Ni 2p (B), S 2p (C), O 1s (D), N 1 ss (B), and C1 s (F) region of NCP.

Fig. 6. (A) Nitrogen adsorption-desorption isotherms and (B) pore size distributions of NSH and NCP.

Fig. 7. Electrochemical testing of the NCP (NSH/cPPyTh) showing (A) cyclic voltammogram, (B) charge-discharge, (C) plot of the variation of capacity at different current density, and (D) impedance plot before and after stability run.

Fig. 8. (A) Schematic diagram showing asymmetric supercapacitor device assembly, (B) cyclic voltammogram (C) charge-discharge characteristics (D) plot showin; the variation of specific capacitance and capacity with varying current density (E) Nyquist plot with the equivalent electrical circuit used to fit the Nyquist plot in th inset before and after 10,000 cycles of operation of the ASC device.

The different ratios of NSH to cPPyTh in the NCP electrode prepared. Table 1

Comparison of the performance of the device reported in this manuscript with some of the recent works of literatures Table 2 ASC, Cyclic voltammetry and charge-discharge characteristics of NCP with 10% cPPyTh, Impedance plot comparing the behaviour of NSH and different NCP electrodes, Variation in resistive circuit elements obtained from the Nyquist plot of NCP//KOH//MAC ASC device, Cyclic voltam- metry behaviour of NCP//KOH//MAC ASC device before and after the stability run. wrote the manuscript, Bharath Madhu synthesised the copolymer and characterised, executed the work along with Anish, Ajay Mohan measured TEM and BET and interpreted the results and N. Sandhyarani conceptualised the idea, supervised and discussed the work, edited the manuscript and brought funding for the work.

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A unique strategy for preparing single-phase unitary/binary oxides–graphene composites

by Chih-I Chang

2010, Chemical Communications

This study proposes a novel two-step strategy to prepare singlephase unitary/binary oxides–graphene composites: precipitating hydroxides followed by microwave-assisted hydrothermal or solvothermal annealing.

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Monomer Concentration Effect on Electrochemically Modified Carbon Fiber with Poly[1-(4- Methoxyphenyl)-1H-Pyrrole] as Microcapacitor Electrode

by Murat Ateş

In this study, films of poly[1-(4-methoxyphenyl)-1H-pyrrole] [poly(MPPy)] were electrochemically grown on carbon fiber microelectrodes (CFMEs) in 0.05 M of tetraethyl ammonium perchlorate–dichloromethane. The effect of different monomer... more

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Hybrid energy storage: the merging of battery and supercapacitor chemistries

by vanesa ruiz

2015, Chem. Soc. Rev.

The integration of capacitive and faradaic energy storage mechanism in the form of hybrid materials, electrodes and devices aims at increasing energy and power densities for the next generation of electrochemical energy storage devices.

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Scan Rate Effect of 1-(4-methoxyphenyl)-1H-Pyrrole Electro-coated on Carbon Fiber: Characterization via Cyclic Voltammetry, FTIR-ATR and Electrochemical Impedance Spectroscopy

by Murat Ateş

Poly(1-(4-methoxyphenyl)-1H-Pyrrole) films were electrodeposited onto carbon fiber micro electrodes with different deposition rates by using cyclic voltammogram in the presence of tetraethyl ammonium perchlorate (TEAP) / dichloromethane... more

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Progress in the electrochemical modification of graphene-based materials and their applications

by Mohd Ali Hashim

2013, Electrochimica Acta

Graphene is a 2D allotrope of carbon with exciting properties such as extremely high electronic conductivity and superior mechanical strength. It has considerable potential for applications in fields such as bio-sensors, electrochemical... more

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Progress in the electrochemical modification of graphene-based materials and their applications

by Muhammad Irfan

2013, Electrochimica Acta

Highlights Six means of functionalising graphene electrochemically is reviewed Electrochemical functionalization is relatively new to other standard methods The technique is expected to improve graphene's application range considerably

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Developments in plane parallel flow channel cells

by Frank C Walsh

Current Opinion in Electrochemistry

Plane parallel electrodes are favoured, in laboratory studies and industry for electrosynthesis, environmental treatment and energy conversion. This electrode geometry offers uniform current distribution while a flow channel ensures a... more

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Differential Pulse Voltammetric Determination of Paracetamol Using Activated Glassy Carbon Electrode

by Meselu Eskezia and

2021, American Journal of Physical Chemistry

The electrochemical property of paracetamol was investigated at a glassy carbon electrode and activated glassy carbon electrode. Differential pulse voltammetry and cyclic voltammetry were used as diagnostic techniques in the determination... more

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