Intercalation engineering of layered vanadyl phosphates for high performance zinc-ion batteries

Aqueous zinc-ion batteries (ZIBs) have attracted great attention as the candidates for large-scale energy storage system, recently, because of their low cost, environment-friendly, high safety, and high theoretical energy densities. Among the numerous cathode materials, layered structure vanadium based polyanionic compounds, such as VOPO4, exhibit high specific capacity for Zn ion storage. However, the low Zn ion diffusion coefficient and limited interlayer spacing make the cathodes low reversible capacity and inferior cycling stability. Herein, K ions were pre-intercalated into the VOPO4 layers via ions exchange adopting VOPO4 center dot 2H(2)O as the precursor. When evaluated as the cathode for ZIBs, an excellent cycle stability of 400 cycles under a current density of 500 mA g(-1) was achieved by the obtained KVOPO4 electrode, verifying the positive effect of intercalation engineering. Furtherly, a solid-solution reaction Zn ion storage mechanism was confirmed. This study provides a new insight to explore high performance cathode materials for ZIBs. (C) 2021 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

In this study, pre-intercalation of K ions into VOPO4 layers improved the cycling stability and performance of cathode materials. The obtained KVOPO4 electrode showed excellent cycle stability in ZIBs with the positive effect of intercalation engineering.