Charge compensation endows K0.16Na0.05(NH4)0.71V4O10−x·0.63H2O cathode with tunable lattice strain for efficient Zn2+ storage

Abstract

The major challenges in using NH₄V₄O₁₀ as a cathode for aqueous zinc-ion batteries (AZIBs) are its unsatisfactory structural stability and carrier migration coefficient due to the accumulated lattice strain during cycling. Herein, we developed a K_0.16Na_0.05(NH₄)_0.71V₄O_10−x·0.63H₂O (NaKNVOH) cathode to achieve a continuous contribution of cathode structure for Zn²⁺ storage at both low and high current density. Both experimental data and DFT calculations confirmed that the charge compensation of Na⁺ and K⁺ not only reinforced the host structure but also enriched the active sites for Zn²⁺ migration. Especially, the structure-led charge compensation effectively alleviated the lattice strain accumulation during prolonged cycling. The NaKNVOH cathode delivered a specific capacity of 495.4 mAh g⁻¹ at 0.5 A g⁻¹, a rate capability of 177.8 mAh g⁻¹ at 4 A g⁻¹, and excellent cycle life and capacity retention at current densities of 0.5 A g⁻¹ (300 cycles, 94.2%) and 4 A g⁻¹ (2000 cycles, 96.57%).