Electrospinning is a nano-fabrication technique that easily produces ceramic oxide nanofibres whi... more Electrospinning is a nano-fabrication technique that easily produces ceramic oxide nanofibres which can find numerous applications as energy storage materials, such as battery electrodes. Vanadium oxide is a viable alternative electrode material with tuneable oxidation states and a layered structure that can reversibly intercalate charge carriers. This review examines the use of vanadium oxide as an electrode material for metal ion batteries with focus on electrospun derivatives. Vanadium oxide-based electrodes are predominantly considered in lithium ion batteries given the amount of published literature in this context. The use of vanadium oxide in energy storage devices, while promising, is limited by its low structural stability and slow electrochemical kinetics associated with charge carrier intercalation resulting in poor cycle stability. Doping with other metallic element and incorporation of carbon derivatives in vanadium oxides can potentially improve its cycle stability and rate retention. Vanadium oxide-based electrodes for sodium ion and aluminium ion batteries are also discussed to highlight its versatility in alternative metal ion battery systems.
Developing durable redox materials with fast and stable redox kinetics under high-temperature ope... more Developing durable redox materials with fast and stable redox kinetics under high-temperature operating conditions is a key challenge for an efficient industrial-scale production of synthesis gas via two step solar thermochemical redox cycles. Here, we investigate novel electrospun nano-structured La 3+ -doped strontium manganites, LSM (La x Sr 1-x MnO 3 , x = 0, 0.25, 0.50, and 1) for an efficient CO production with high redox kinetics. The oxidation behaviour of these LSM powders was assessed in terms of oxygen recovery and CO yield via thermogravimetric analysis by using air and CO 2 as oxidation medium. Strontium manganate (SrMnO 3 ) shows the highest CO yield per cycle of 854.20 µmol g -1 at a rate of ~400 µmol g -1 min -1 when reduced at 1400°C and re-oxidized at 1000°C, with high oxygen exchange capacity in terms of oxygen non-stoichiometry of up to 0.29, during CO 2 splitting cycles. However, lanthanum manganite (LaMnO 3 ) demonstrated high yield of CO of 329 µmol g -1 with a rate of 329 µmol g -1 when reduced at 1000°C and re-oxidized at 700°C, which is three times higher than the yield for SrMnO 3 at the same conditions. The oxygen recovery in LSM samples was 4-15% higher during oxidation with air than with CO 2 . Moreover, the improved structural stability of these nano-powders indicates the potential of electrospinning technique for an up-scale synthesis of oxygen carriers. These findings show that a selective LSM system can be utilized for enhanced CO yield with high kinetics and structural stability at reduction temperatures 1000-1400°C.
Journal of Solid State Electrochemistry, Aug 25, 2018
The structural and electrochemical effects of electrospun V2O5 with selected redox-inactive dopan... more The structural and electrochemical effects of electrospun V2O5 with selected redox-inactive dopants (namely Na + , Ba 2+ , and Al 3+ ), have been studied. The electrospun materials have been characterised via a range of analytical methods including X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller surface area measurements, scanning and transmission electron microscopy. The incorporation of dopants in V2O5 was further studied with computational modelling. Structural analysis suggested that the dopants had been incorporated into the V2O5 structure with changes in crystal orientation and particle size, and variations in the V 4+ concentration. Electrochemical investigations using potentiodynamic, galvanostatic and impedance spectroscopy analysis, showed that electrochemical performance might be dependent on V 4+ concentration, which influenced electronic conductivity. Na + or Ba 2+ doped V2O5 offered improved conductivities and lithium ion diffusion properties, while Al 3+ doping was shown to be detrimental to these properties. The energetics of dopant incorporation, calculated using atomistic simulations, indicated that Na + and Ba 2+ occupy interstitial positions in the interlayer space, while Al 3+ is incorporated in V sites and replaces a vanadyl-like (VO) 3+ group. Overall, the mode of incorporation of the dopants affects the concentration of oxygen vacancies and V 4+ ions in the compounds, and in turn their electrochemical performance. Dopants of varying oxidation states incorporated into electrospun V2O5 are studied. Doping showed significant impacts on the crystallinity and V 4+ concentration. 2 at% Na + and 3 at% Ba 2+ in V2O5 improved electrochemical performance. Doping 3 at% Al 3+ in V2O5 did not improve electrochemical performance.
Recently, there has been growing interest in the application of transition metal oxalates as ener... more Recently, there has been growing interest in the application of transition metal oxalates as energy storage materials. In addition to energy storage applications, these materials also offer the potential to act as a carbon sink, thereby offering an opportunity for more sustainable/greener energy storage materials. Over the past decade, the electrochemical performance of transition metal oxalates has been explored in the context of various energy storage devices such as lithium ion batteries, sodium ion batteries, supercapacitor electrodes and redox flow batteries. This review presents recent work and advances relating to the application of transition metal oxalates as potential energy storage materials. Transition metal oxalates are a versatile material, with a variety of roles depending on the energy storage method (e.g. conversion-type negative electrode material in lithium ion batteries or stabiliser additive in redox flow batteries). Mn, Fe, Cu, Ni, Co and Zn based oxalates have been investigated predominantly in the context of lithium ion batteries and supercapacitors, with electrochemical performances comparable to and at times better than their equivalent oxides. Although their performances can be improved via elemental substitution and mixing with carbon-based materials, details of the electrochemical reactions are still not fully understood.
Developing durable redox materials with fast and stable redox kinetics under high-temperature ope... more Developing durable redox materials with fast and stable redox kinetics under high-temperature operating conditions is a key challenge for an efficient industrial-scale production of synthesis gas via two step solar thermochemical redox cycles. Here, we investigate novel electrospun nano-structured La 3+-doped strontium manganites, LSM (La x Sr 1-x MnO 3 , x = 0, 0.25, 0.50, and 1) for an efficient CO production with high redox kinetics. The oxidation behaviour of these LSM powders was assessed in terms of oxygen recovery and CO yield via thermogravimetric analysis by using air and CO 2 as oxidation medium. Strontium manganate (SrMnO 3) shows the highest CO yield per cycle of 854.20 µmol g-1 at a rate of ~400 µmol g-1 min-1 when reduced at 1400°C and re-oxidized at 1000°C, with high oxygen exchange capacity in terms of oxygen non-stoichiometry of up to 0.29, during CO 2 splitting cycles. However, lanthanum manganite (LaMnO 3) demonstrated high yield of CO of 329 µmol g-1 with a rate of 329 µmol g-1 when reduced at 1000°C and re-oxidized at 700°C, which is three times higher than the yield for SrMnO 3 at the same conditions. The oxygen recovery in LSM samples was 4-15% higher during oxidation with air than with CO 2. Moreover, the improved structural stability of these nano-powders indicates the potential of electrospinning technique for an up-scale synthesis of oxygen carriers. These findings show that a selective LSM system can be utilized for enhanced CO yield with high kinetics and structural stability at reduction temperatures 1000-1400°C.
Electrospinning is a nano-fabrication technique that easily produces ceramic oxide nanofibres whi... more Electrospinning is a nano-fabrication technique that easily produces ceramic oxide nanofibres which can find numerous applications as energy storage materials, such as battery electrodes. Vanadium oxide is a viable alternative electrode material with tuneable oxidation states and a layered structure that can reversibly intercalate charge carriers. This review examines the use of vanadium oxide as an electrode material for metal ion batteries with focus on electrospun derivatives. Vanadium oxide-based electrodes are predominantly considered in lithium ion batteries given the amount of published literature in this context. The use of vanadium oxide in energy storage devices, while promising, is limited by its low structural stability and slow electrochemical kinetics associated with charge carrier intercalation resulting in poor cycle stability. Doping with other metallic element and incorporation of carbon derivatives in vanadium oxides can potentially improve its cycle stability and rate retention. Vanadium oxide-based electrodes for sodium ion and aluminium ion batteries are also discussed to highlight its versatility in alternative metal ion battery systems.
Recently, there has been growing interest in the application of transition metal oxalates as ener... more Recently, there has been growing interest in the application of transition metal oxalates as energy storage materials. In addition to energy storage applications, these materials also offer the potential to act as a carbon sink, thereby offering an opportunity for more sustainable/greener energy storage materials. Over the past decade, the electrochemical performance of transition metal oxalates has been explored in the context of various energy storage devices such as lithium ion batteries, sodium ion batteries, supercapacitor electrodes and redox flow batteries. This review presents recent work and advances relating to the application of transition metal oxalates as potential energy storage materials. Transition metal oxalates are a versatile material, with a variety of roles depending on the energy storage method (e.g. conversion-type negative electrode material in lithium ion batteries or stabiliser additive in redox flow batteries). Mn, Fe, Cu, Ni, Co and Zn based oxalates have been investigated predominantly in the context of lithium ion batteries and supercapacitors, with electrochemical performances comparable to and at times better than their equivalent oxides. Although their performances can be improved via elemental substitution and mixing with carbon-based materials, details of the electrochemical reactions are still not fully understood.
Ferrous oxalate from carbon dioxide and scrap mild steel stores more energy and carbon than irons... more Ferrous oxalate from carbon dioxide and scrap mild steel stores more energy and carbon than irons oxides prepared from oxalates.
Uploads
Papers by Joyce Yeoh