Aqueous rechargeable electrochemical energy storage (EES) devices using K-ions as charge carriers are attractive due to their superior safety, lower cost and excellent transport properties compared to other alkali ions. However, the accommodation of K-ions with satisfactory capacity and cyclability is difficult because their large ionic radius of K-ions causes structural distortion and instabilities even in layered electrodes. Here we report that water induces structural rearrangements of the [VO6] octahedra and enhances stability of the highly disordered K-intercalated V2O5 nanosheets (KVO), evidenced by neutron total scattering measurements and pair distribution functional analysis. The KVO engaged by structural water achieves high capacity (183 mAh g-1 in half-cells at a scan rate of 5 mV s-1, corresponding to 0.89 charge per vanadium atom) and excellent cyclability (62.5 mAh g-1 in full-cells after 5,000 cycles at 10 C). The promotional effects of structural water on the disordered KVO will contribute to the exploration of disordered structures from earth-abundant elements for EES applications.

Structural water engaged disordered vanadium oxide nanosheets for high capacity aqueous K-ion storage

255th National Meeting (2018)

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