High-mass loading V3O7•H2O nanoarray for Zn-ion battery: New synthesis and two-stage ion intercalation chemistry

Vanadium-based materials are promising cathode materials for aqueous rechargeable zinc-ion batteries (ZIBs). However, up to now, the detailed Zn ion intercalation mechanisms are still not fully clear. In this work, we first show a new facile synthesis approach for V3O7 center dot H2O nanoarray cathode with large mass loadings (1.0-12 mg cm(-2)). An empirical model is proposed to assess the utilization ratio of active materials under different mass loadings. Then, through the combination of first-principles calculations and a series of ex-situ characterizations, we identify for the first time a two-step Zn2+ intercalation mechanism in V3O7 center dot H2O. The stepwise and reversible intercalation process is manifested by different diffusion energy barriers and segmented electrochemical kinetics in various discharge depths. The nanoarray binder-free electrode is also applied in pouch cells which show high capacities than state-of-the-art ZIB pouch cells. This study may provide an elucidation for the disputed Zn2+ intercalation chemistry of vanadium-based cathodes in ZIBs as well as a guidance to the design of high-massloading battery materials.

Automated summary

In this study, a new synthesis approach for V3O7 center dot H2O nanoarray cathode with large mass loadings is introduced, along with an empirical model to evaluate the utilization ratio of active materials. By combining first-principles calculations and ex-situ characterizations, a two-step Zn2+ intercalation mechanism in V3O7 center dot H2O is identified for the first time, providing insights for the design of high-massloading battery materials.