Synergistic interlayer and structure engineering construction of layered hydrated vanadates/graphene for stable aqueous zinc-ion batteries

Vanadium-based oxides have attracted much attention due to their open framework structure and multiple oxygen coordination polyhedral. Herein, the novel hydrated vanadates (CaV8O20•3 H2O) nanoribbons with graphene are prepared, which are used as a cathode material for aqueous zinc-ion batteries (AZIBs). Specifically, Ca-ion and crystal water as a pillar enhance the layered frameworks stability and decrease the electrostatic interaction with Zn2+. Meanwhile, the introduction of graphene is helpful to further strengthen the electrical conductivity and fast electron transfer. Most importantly, the amount of graphene oxides (GO) precursor would induce the structural transitions of oxygen coordination polyhedral (CaV6O16•3 H2O to CaV8O20•3 H2O). Benefiting from the combination of interlayer and structure engineering strategy, the optimized CaVO-400 not only offers a high reversible capacity (290.9 mAh g−1 at 1 A g−1 after 100 cycles) but exhibits a good cycling performance (56.4 mAh g−1 at 3 A g−1 after 10000 cycles). Especially, the CaVO-400 shows a superior rate capability (197.9 mAh g−1 at 10 A g−1). Furthermore, through the detailed phase transition and kinetics analysis, we studied the Zn2+/H+ insertion/extraction mechanism behind the good electrochemical performance. Accordingly, this work provides a reasonable strategy for the study of Vanadium-based oxides cathode materials for AZIBs.