Preparation of NaV${}_6$O${}_{15}$ nanosheet cathodes with high cycling performance and good capacity retention rate in aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) have become a promising alternative energy storage device due to their lower cost and better safety performance than lithium-ion batteries (LIBs). However, the biggest challenge is the need to develop electrode materials with higher capacity and longer life than LIBs at present. Herein this work, a tunnel-structured sodium vanadate (NaV${}_6$O${}_{15}$) is synthesized by molten salt method as the cathode materials for AZIBs. The prepared NaV${}_6$O${}_{15}$ nanosheets have a high specific capacity of 325 mAh g${}^{-1}$ at a current density of 0.1 A g${}^{-1}$, and the capacity retention rate is as high as 127.08% under 1000 cycling at a current density of 1 A g${}^{-1}$. This excellent performance is mainly attributed to the stable tunneled structure, which provides an effective diffusion path for Zn${}^{2+}$ insertion and avoids structural damage. Herein the subsequent cycles, Zn${}^{2+}$ is mainly inserted/extracted in NaV${}_6$O${}_{15}$ and Zn${}_3$(OH)${}_2$V${}_2$O${}_7$·2H${}_2$O. The preparation of NaV${}_6$O${}_{15}$ cathode materials and the molten salt method provide a certain reference value for the development of AZIBs in this work. (© 2022 Wiley‐VCH GmbH)