A high-entropy zero-strain V-based cathode for high performance aqueous zinc-ion batteries

Abstract

Layered V-based V₂O₅·nH₂O cathodes hold the merits of large Zn²⁺ diffusible interlayer spacing (11.5 Å) and high theoretical capacity (589 mA h g^-1) in aqueous zinc-ion batteries (AZIBs). Meanwhile, they still suffer from defects of inferior structural stability and low intrinsic bulk conductivity. Herein, a high-entropy designed V₂O₅·0.48H₂O cathode is developed by incorporating Na⁺, Ni²⁺, Zn²⁺, Al³⁺, and F^- via a typical hydrothermal method. In-situ XRD and in-situ DRT trials profoundly clarify the impeccable zero-strain structural reversibility and stability, as well as augmented bulk conductivity during charging-discharging process. DFT calculations further verify the enhanced electronic transition capability and reduced diffusion energy barriers for the high-entropy cathode. This high-entropy cathode delivers superior working capacity (583.7 mA h g^-1@0.06 A g^-1), rate capabilities (200 mA h g^-1@30 A g^-1), and long-term cycle stability (351 mA h g^-1@6 A g^-1@5000 cycles@95.7%) with competent energy density (438 W h kg^-1). Also, the pouch-cells with high-loading (80 mg) give reliable cycle and rate performance at both room (25 ℃; 451.3 mA h g^-1@0.06 A g^-1; 391.4 mA h g^-1@0.6 A g^-1@1000 cycles@94.6%) and low (-30 ℃; 190 mA h g^-1@3 A g^-1@2000 cycles@94%) temperatures, revealing enormous practicality and scientific values for advanced AZIBs.