Nitrogen-Vacancy-Rich VN Clusters Embedded in Carbon Matrix for High-Performance Zinc Ion Batteries

Vanadium nitride (VN) is a potential cathode material with high capacity and high energy density for aqueous zinc batteries (AZIBs). However, the slow kinetics resulting from the strong electrostatic interaction of the electrode materials with zinc ions is a major challenge for fast storage. Here, VN clusters with nitrogen-vacancy embedded in carbon (C) (N_v-VN/C-SS-2) are prepared for the first time to improve the slow reaction kinetics. The nitrogen vacancies can effectively accelerate the reaction kinetics, reduce the electrochemical polarization, and improve the performance. The density functional theory (DFT) calculations also prove that the rapid adsorption and desorption of zinc ions on N_v-VN/C-SS-2 can release more electrons to the delocalized electron cloud of the material, thus adding more active sites. The N_v-VN/C-SS-2 exhibits a specific capacity and outstanding cycle life. Meanwhile, the quasi-solid-state battery exhibits a high capacity of 186.5 mAh g^-1, ultra-high energy density of 278.9 Wh kg^-1, and a high power density of 2375.1 W kg^-1 at 2.5 A g^-1, showing excellent electrochemical performance. This work provides a meaningful reference value for improving the comprehensive electrochemical performance of VN through interface engineering.