Considering the environmental pollution crisis caused by fossil fuel and the limited supply of those, developing alternative power stations is strongly urged. Accompanying the development of alternative power stations, the introduction of large-scale stationary energy storage systems (ESSs) connected with the electrical power grid is vital for enhanced accessibility of electricity and leveling-off the intermittent spikes in the generated power. Li ion batteries (LIBs) have been successfully demonstrated as feasible power sources for portable devices. Nonetheless, the application of LIBs into ESSs faces obstacles due to the limited source and continuously increasing cost of raw lithium and high flammability and the high cost of the organic electrolytes. Consequently, aqueous rechargeable batteries (ARBs) with readily accessible electroactive guest ions of H3O+, Na+, or Mg2+, are the most suitable energy devices for ESSs. Very recently, Prussian blue analogues (PBAs) have been highlighted as a promising candidate of electrode materials for ARBs due to their ideal crystal structure and desirable electrochemical characteristics. Despite the unique advantages of the PBAs, the capacity of PBAs delivered in aqueous systems has been limited to ~60 mAhg-1 because only single species of transition metal ions incorporated into the PBAs were electrochemically activated. Herein, vanadium hexacyanoferrate (V/Fe PBA) is proposed as a breakthrough to this limitation, and their electrochemical performance as a cathode for aqueous rechargeable batteries (ARBs) was investigated for the first time. The V/Fe PBAs provided an improved capacity of ~ 100 mAh-1 under a C-rate of ~ 0.55 C, taking advantage of the multiple-electron redox reactions of V and Fe ions. In addition, the mechanism of energy storage and the cycling behavior were elucidated by monitoring the ex-situ X-ray absorption near-edge spectra, microstructural changes, dissolution of the transition metal ions, and changes in the resistance of charge transfer and surface layer during cycling.

Vanadium hexacyanoferrates Prussian blue analogues for multiple-redox enabled high performance aqueous rechargeable batteries

253rd National Meeting (2017)

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