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

Abstract

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