Deficiency and Surface Engineering Boosting Electronic and Ionic Kinetics in NH4V4O10 for High-Performance Aqueous Zinc-Ion Battery

Abstract Aqueous zinc-ion batteries present their unique advantages, such as cost-efficient and non-flammability for large-scale energy storage. However, their widespread application is hindered by the development of cathode materials, sluggish intrinsic ion/electron kinetics, and unsatisfied structural stability. Herein, we report a high-performance NH4V4O10 cathode with oxygen vacancy (denoted as NH4V4O10-x) and reduced graphene oxide (rGO) surface modification. The oxygen vacancies enhance the Zn2+ diffusion ability and stabilize the NH4V4O10 structure. Meanwhile, the density functional theory calculations further confirm the deficiency engineering leads to high electronic conductivity, weak electrostatic interaction, and low Zn2+ diffusion barrier. In addition, the rGO surface modification provides fast electron transfer. The NH4V4O10-x@rGO delivers high capacity (391 mAh g−1 at 1A g−1), impressive rate ability (211 mAh g−1 at the 15A g−1), and stable cycle performance with 90.5 % capacity retention after 2000 cycles. This work provides a reasonable strategy to design cathode materials with deficiency and surface engineering to improve the electrochemical performance of zinc-ion batteries.