High-entropy V-based cathode for high-capacity and long-life aqueous zinc-ion battery

Abstract

Layered hydrated V₂O₅·xH₂O cathodes are endowed with the advantage of sufficient theoretical specific capacity (589 mA h g^-1) in aqueous zinc-ion batteries (AZIBs), yet accompanied by poor bulk conductivity and structural collapse during long-periodic cycling. Herein, we design a series of high-entropy doped V₂O₅·0.48H₂O by incorporating Na⁺/Al³⁺/Ni²⁺/NH₄⁺/F^- into interlayer simultaneously. In-situ XRD and in-situ DRT analyses profoundly elucidate the enormously enhanced structural reversibility/stability and faster electron/ion transfer efficiency derived from the high-entropy effects. DFT calculations clarify the augmented bulk electronic conductivity stemming from the more abundant electron cloud density near the Fermi level and more conduction and valence bands available for transition. Benefiting from the high-entropy design, the optimal cathode in coin-cells can display competitive discharge capacity of 546 mA h g^-1 at 0.1 C, rate capabilities (458 mA h g^-1@1 C; 322 mA h g^-1@10 C), and cyclic stability (5000 cycles@10 C@98% retention). Also, the pouch-cells with high-load (65 mg) also deliver superior cyclic and rate performance at both room (190 mA h g^-1@1000 cycles@86.8% retention; 25 ℃) and low temperature (171 mA h g^-1@200 cycles@82.3% retention; -20 ℃), manifesting valuable insights for designing ultra-high-capacity V-based cathodes with long-life stability for AZIBs.