Engineering hydrated vanadium oxide by K+ and Ni2+ incorporation for aqueous zinc ion batteries

It is confirmed that K+ introduction is a feasible approach to lead hydrated vanadium pentoxide to a new phase of KVOH which is considered a cathode material with substantial potential for aqueous zinc ion batteries (ZIBs). Nevertheless, the desire to pursue higher value of specific capacity is still a barrier to its development of applications. Herein, a Ni-doped KVOH (KNiVOH) is developed to achieve higher value of specific capacity. Besides, Ni2+ introduction can intensify the conductivity and encourage the electronic rearrangement, which is advantageous to the electrochemical characteristic and chemical kinetics of the KNiVOH. Furthermore, Ni2+ can make KVOH's K–O bond become more stable by decreasing the energy of formation. As regards the specific capacity value, KNiVOH displays the value of 275 mAh g−1 at 5A g−1, which is better than KVOH (266 mAh g−1). Consequently, these properties recommend KNiVOH as a promising cathode material candidate of ZIBs, indicating it is a practical strategy to combine potassium with other transition metals to synthesize new cathode materials for ZIBs in the future.