Printed Energy Storage Devices

Journal of The Electrochemical Society, 2003

To prepare miscible polyethylene glycol diacrylate/polyvinylidene fluoride ͑PEGDA/PVdF͒ blend gel polymer electrolytes, low molecular weight (M ϭ 742) liquid PEGDA oligomer was mixed with PVdF-HFP dissolved in ethylene carbonate/dimethyl carbonate/LiPF 6 liquid electrolytes, and then cured under ultraviolet irradiation. Room temperature conductivity of PEGDA/PVdF blend films was found to be comparable to that of PVdF-HFP gel polymer electrolytes, and they were electrochemically stable up to 4.6 V vs. Li/Li ϩ. Scanning electron micrographs revealed that PEGDA/PVdF blend electrolytes have pore size intermediate between dense PEGDA and highly porous PVdF-HFP. It was confirmed by weight change measurement that liquid electrolyte was likely to evaporate through large pores in PVdF-HFP at 80°C, while PEGDA/PVdF blend showed better liquid electrolyte retention ability. This result was in good agreement with more stable interfacial properties of PEGDA/PVdF blend at 80°C in ac impedance analysis. Consequently, both PVdF-HFP and PEGDA/PVdF gel polymer electrolytes delivered similar discharge capacity at room temperature, but PEGDA/PVdF blend gel polymer electrolyte showed much better cycle performance than pure PVdF-HFP at 80°C.

Ionics, 2017

Ionic liquid-based gel polymer electrolyte (GPE) has been synthesized using standard solution cast technique. Different weight percent of ionic liquid, 1-Butyl-3methylimidazolium chloride (BMIMCl) and liquid electrolyte, ethylene carbonate (EC)-propylene carbonate (PC)-tetra ethyl ammonium tetra fluoro borate (TEABF 4) was incorporated in polymer, poly(vinylidene fluoride-co-hexafluoro propylene (PVdF-HFP) to obtain mechanically stable gel polymer electrolyte film (GPE) having maximum conductivity of 10 −3 S cm −1 at room temperature, which is acceptable from device fabrication point of view. Potential window and ionic transference number has been obtained to examine the potential limit and ionic characteristics of optimized GPE system. Temperature dependence behavior of electrical conductivity curve follows Arrhenius nature in the temperature range of 303-373 K. Pattern of dielectric constant and its loss as a function of frequency and temperature have been studied and is being explained on the basis of electrode interfacial polarization effect. Frequency-dependent conductivity spectra obey the Jonscher's power law. Further, optimized composition of GPE has been tested successfully for its application in supercapacitor fabrication with activated charcoal as an electrode material. Maximum specific capacitance of 118.6 mF cm −2 equivalent to single electrode specific capacitance of 61.7 F g −1 have been observed for the optimized GPE film.

2007

Abstract Microfabrication of on-chip solid state electrochemical cells has provided a robust challenge to industry for the past decade. Previous efforts include RF Sputtering, screen-printing, and laser printing. All have merit in the laboratory but have proven difficult to scale due a combination of equipment cost and proper isolation from water and oxygen.

Due to the low energy density of commercial printable dielectrics, printed capacitors occupy a significant printing area and weight in fully printed electronics. It has long remained challenging to develop novel dielectric materials with printability and high energy-storage density. Here, we present the inkjet printing of all aqueous colloidal inks to dielectric capacitors composed of carbon nanotube electrodes and polyvinylidene fluoride (PVDF)-based dielectrics. The formulated dielectric ink is composed of PVDF latex particles coated by protonated chitosan molecules. Beyond the isoelectric point, the ink demonstrates excellent printability and film-forming properties. Chitosan serves as a strong binder to largely improve the printed film quality yet it introduces charged species. To confine the transport of these mobile charges, the printed PVDF@Chitosan layer was interlayered by a boron nitride nanosheet nanolayer. This layer is perpendicular to the electric field and serves as a...

2006

Abstract A direct write dispenser printing system demonstrates a flexible method for integrating electrochemical energy storage components onto an autonomous device. The capacitor's function will be to extend the lifetime of a rechargeable battery by absorbing the high power demands of the electronic device. Electrochemical capacitors based on mesocarbon microbeads suspended in a poly (vinylidene fluoride) polymer binder are printed onto a substrate.

Journal of power …, 2006

The secondary liquid-electrolyte based lithium-ion battery is well accepted in the commercial market. But, their manufacturing cannot fulfill the present demand arises by a growing electronic market. As the electronic goods are becoming smaller, thinner, though they need high ...

Journal of The Electrochemical Society, 2007

Ionic liquids thermodynamically compatible with Li metal are very promising for applications to rechargeable lithium batteries. 1-methyl-3-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P 13 TFSI) is screened out as a particularly promising ionic liquid in this study. Dimensionally stable, elastic, flexible, nonvolatile polymer gel electrolytes (PGEs) with high electrochemical stabilities, high ionic conductivities and other desirable properties have been synthesized by dissolving Li imide salt (LiTFSI) in P 13 TFSI ionic liquid and then mixing the electrolyte solution with poly(vinylideneco-hexafluoropropylene) (PVDF-HFP) copolymer. Adding small amounts of ethylene carbonate to the polymer gel electrolytes dramatically improves the ionic conductivity, net Li ion transport concentration, and Li ion transport kinetics of these electrolytes. They are thus favorable and offer good prospects in the application to rechargeable Li batteries including open systems like Li/air batteries, as well as more "conventional" rechargeable lithium and lithium ion batteries. As is well known, Li is the most electropositive and lightest metal, and thus has the greatest theoretical specific capacity of 3860 Ah/kg.1 , 2 This has attracted worldwide efforts of researchers and manufacturers to develop advanced battery technologies based on lithium. To date, the rechargeable lithium ion battery has already been one of the best choices in view of specific capacity and cycle stability. 1 However, rechargeable lithium metal batteries with even higher specific capacities are still unavailable in the market, especially lithium/air batteries which possess the highest theoretical specific energy (as high as 13,000 Wh/g, excluding the oxygen from the air). Conventional Li/air batteries based on aqueous electrolytes suffer from fast capacity loss due to corrosion of lithium by water and are also nonrechargeable. Abraham and Jiang first reported a rechargeable lithium/oxygen cell using organic polymer gel electrolytes and demonstrated its advantages such as an all solid state design, rechargeablity and a high capacity. 3 Read studied the effect of electrolyte and air cathode formulation on the electrochemical properties of an Li/O 2 organic electrolyte cell and found that electrolyte composition has the largest effect on discharge capacity and rate capability. 4 Both groups incorporated common organic solvents in the electrolyte, i.e., ethylene carbonate (EC), propylene carbonate (PC), 1,2-dimethoxyethane, diethyl carbonate (DEC), dimethyl carbonate, γ-butyrolactone, tetrahydrofuran, or tetrahydropyran. 3, 4 The highly reactive lithium metal cannot, however, be thermodynamically compatible with common organic solvents. The fact that the air cathode of Li/air cells must be open to the ambient environment poses

Journal of Solid State Electrochemistry, 2018

Since the mechanism of charge storage in electrical double-layer capacitors (EDLCs) relies on diffusion of ions into the pores of the electrodes, in general, a much lower capacitance is expected for gel-based electrolytes than liquid electrolytes. However, in this work, we have found that the specific capacitance in gel-based electrolytes made of polyvinyl alcohol (PVA) and an acid (H 2 SO 4 or H 3 PO 4) is even higher than the specific capacitances of similar devices with liquid acid-based electrolytes. We have discovered that the reason is due to the gel being a redox active material with the capability of charge storage in the volume of the electrolyte. In this work, solid-state and flexible devices with both H 2 SO 4-PVA and H 3 PO 4-PVA electrolytes were fabricated and characterized. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods were applied to estimate the capacitance associated to the gel electrolytes. Also, a relatively high cycling stability of 97.5% for H 2 SO 4-PVA and 95% for H 3 PO 4-PVA was obtained after 1000 charging-discharging cycles. A mechanism of charge storage is proposed to explain the redox active behavior of the gel electrolyte. The presented results are promising for employment of PVA gel electrolytes in some low-cost applications.

We report the design of an all-solid-state supercapacitor, which has charge storage characteristics closely matching that of its liquid-state counterpart even under extreme temperature and humidity conditions. The prototype is made by electro-depositing polyethylenedioxythiophene (PEDOT) onto the individual carbon fibers of a porous carbon substrate followed by intercalating the matrix with polyvinyl alcohol–sulphuric acid (PVA–H2SO4) gel electrolyte. The electrodeposited layer of PEDOT maintained a flower-like growth pattern along the threads of each carbon fiber. This morphology and the alignment of PEDOT led to an enhanced surface area and electrical conductivity, and the pores in the system enabled effective intercalation of the polymer–gel electrolyte. Thus, the established electrode–electrolyte interface nearly mimics that of its counterpart based on the liquid electrolyte. Consequently, the solid device attained very low internal resistance (1.1 U cm
2) and a high specific capacitance (181 F g
1) for PEDOT at a discharge current density of 0.5 A g
1. Even with a high areal capacitance of 836 mF cm
2 and volumetric capacitance of 28 F cm
3, the solid device retained a mass-specific capacitance of 111 F g
1 for PEDOT. This is in close agreement with the value displayed by the corresponding liquid-state system (112 F g
1), which was fabricated by replacing the gel electrolyte with 0.5 M H2SO4. The device also showed excellent charge–discharge stability for 12 000 cycles at 5 A g
1. The performance of the device was consistent even under wide-ranging humidity (30–80%) and temperature (
10 to 80 C) conditions. Finally, a device fabricated by increasing the electrode area four times was used to light an LED, which validated the scalability of the process.

Electrochemistry Communications, 2009

This paper describes a novel strategy to make fully transparent, solid-state and flexible supercapacitors based on room temperature ionic liquid (RTIL) gel and ITO electrodes coated on transparent polymer substrate without a separator, which enables the roll-to-roll technique for fabrication of such supercapacitors as printable devices. This is the first type of transparent electrochemical double layer capacitor (EDLC) based on ionic liquid gel.