Dual effects of Ag+ intercalation boosting the kinetics and stability of NH4V4O10 cathodes for enhanced zinc ion storage

Abstract

Recently, aqueous zinc ion batteries (AZIBs) have emerged as novel energy storage devices for their low cost, favorable safety and high theoretical capacity. However, layered ammonium vanadates, as promising cathode materials, suffer from slow Zn²⁺ diffusion kinetics due to the strong electrostatic interactions between Zn²⁺ and the [VO_n] layer, irreversible deammoniation and poor conductivity. In this work, Ag⁺ intercalated NH₄V₄O₁₀ (ANVO) was synthesized as a high-performance cathode for AZIBs. The pre-intercalated Ag⁺ interacts with the lattice oxygen to form strong Ag–O bonds, acting as “pillars” to stabilize the layered structure in electrochemical reactions. Moreover, the Ag⁰ generated in situ during the discharge process favors enhancement of the electronic conductivity of the material. The dual effects of Ag⁺ intercalation endow AVNO with high structural stability and fast electron/Zn²⁺ diffusion kinetics, leading to superior electrochemical performance. In particular, it exhibits an ultralong cycling life (with 95% capacity retention after 1000 cycles at 5 A g⁻¹) as well as competitive rate performance (473.6 mA h g⁻¹ at 0.2 A g⁻¹ and 286.6 mA h g⁻¹ at 10 A g⁻¹). This research provides valuable insights for designing high-capacity and long-life cathode materials.