A new sodium vanadyl fluorophosphate as a high-rate and stable cathode for aqueous hybrid sodium-zinc batteries.

Herein, a facile solvothermal method is used to prepare a new polyanion-type sodium vanadyl fluorophosphate (Na x (VO) 2 (PO 4 ) y F z ) for aqueous hybrid sodium-zinc batteries. The novel cathode delivers superior performance, which includes a high specific capacity of 87.2 mA h g -1 at 0.05 A g -1 , good rate capability of 41.5 mA h g -1 at 2 A g -1 , and high capacity retention. Based on ex situ XRD and XPS results, the Na + /Zn 2+ co-insertion mechanism is proposed.