Oxygen-vacancy and phosphate coordination triggered strain engineering of vanadium oxide for high-performance aqueous zinc ion storage

Rechargeable aqueous zinc ion batteries based on vanadium oxides have been increasingly studied because of the low cost and high safety. However, the performance of V-based cathodes is limited mainly due to the strong interaction between intercalated zinc ions and the host structure, low electronic conductivity, phase transitions and unstable architectures upon cycling. Here, strain engineering of vanadium oxide, through oxygen vacancy and phosphate group coordination, is developed. The layered structure of vanadium oxide distorts due to the localized strain to form a "cavity", which contributes to the abundant zinc-ion storage sites and weakens the strong interaction. The introduced oxygen defects and phosphate groups also boost charge transfer and increase the electronic conductivity of the cathode. More importantly, due to the repulsive force between the phosphate groups and OH−, the phase transitions on the cathode surface during cycling is impeded, resulting in the stable architecture. Thus, the prepared cathode exhibits a high capacity of 161.8 mA h g−1 at 10 A g−1, a long cycle life (96.8% capacity retention after 3000 cycles) and an outstanding rate performance (124.3 mA h g−1 at 20 A g−1). This strain engineering may provide a rational construction to promote the capacity and durability of cathodes for other advanced batteries.