The difference in peak hours of production of energy from alternative energy sources, such as wind and solar, and peak hours of energy consumption requires the need for large scale energy storage. Layered vanadium oxide are known to possess large interlayer spacing allowing transport of cations with larger radii such as Na+ and K+ which are both more abundant and cheaper than lithium but also have smaller radii of solvation in aqueous solutions. In this study we have successfully synthesized potassium doped vanadium pentoxide nanosheets, K0.2V2O5, utilizing a facile wet chemistry approach. The structure of the nanosheets where characterized utilizing several spectroscopic tools including the atomic pair distribution function (both neutron and X-ray scattering). The vanadium oxide nanosheets were found to be disordered but still possess the bi-layered structure with the large interlayer distance of 1.1 nm. Electrochemical investigations were performed utilizing a concentrated KCl electrolyte in both the three electrode half-cell and symmetric full cell configuration. The K0.2V2O5 exhibited exceptionally high capacitance in the half cell with a 1V potential window, over 600 F/g at 5 mV/s sweep rate but was also able to maintain strong redox features and high capacity at fast sweep rates (over 300 F/g at 200 mV/s). Symmetric full cells were tested at various current densities and are stable through 5000 cycles. Through insitu X-ray diffraction using synchrotron radiation, the reversible expansion and contraction of the vanadium oxide layers was observed during the charge-discharge electrochemical processes. This work aims to provide further understanding of the fundamental insight on the structure-function relationship of the charge storage of K-ion within V2O5 layered nanostructure.

Aqueous energy storage utilizing layered vanadium pentoxide electrodes with high-specific capacity in a KCl elctrolyte

251st National Meeting (2016)

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