Towards high-performance aqueous zinc-ion battery via cesium ion intercalated vanadium oxide nanorods

Layered vanadium oxide cathode materials have attracted extensive attentions in rechargeable aqueous zinc-ion batteries (ZIBs) owing to its large interlayer distance and high capacity. Unfortunately, it suffers from fast capacity decay during long-term cycle due to severe structural collapse. Herein, we intercalate cesium ion (Cs+) into hydrated vanadium pentoxide (V2O5·nH2O) to obtain a reinforce layered structure, which forms strong Cs-O bond with the built-in oxygen atom and enhances the interaction between the layers to avoid the structure collapse. As a result, the Cs+ intercalated material (CsVO) presents an enhanced specific capacity (404.9 mAh g−1 at current density of 0.1 A g−1, 189.9 mAh g−1 at 20 A g−1) and excellent long-term cycle stability (the capacity retention of 89% over 10,000 cycles even at 20 A g−1), that is obviously superior to the bare V2O5·nH2O electrode. Furthermore, Zn2+/H+ co-insertion mechanism in aqueous ZIBs is demonstrated by ex-situ XRD and XPS characterizations.