Dual-track regulation of lattice respiration and interface stability: Zn²⁺ doping and electrolyte engineering towards strain-tolerant vanadium oxide cathodes

Vanadium oxide cathode materials are regarded as one of the most promising candidates for aqueous zinc ion batteries (AZIBs). However, their performance is limited by slow ion diffusion kinetics, low energy storage capacity and vanadium-based dissolution. Herein, a novel strategy of Zn²⁺ doping and the diethylene glycol ether (DGME) electrolyte additive was proposed to regulate the electrochemical properties. Zn²⁺-doped will enhance lattice respiration and broaden Zn²⁺ transfer channels, thus accelerating fast the insertion and extraction of Zn²⁺. Meanwhile, the introduction of DGME electrolyte additives will facilitate the formation of a stable cathode electrolyte interface (CEI) layer on the cathode surface, alleviating the interaction forces and inhibiting the vanadium dissolution. Consequently, the cell delivers a high specific capacity of 615.4 mAh g⁻¹ at 0.5 A g⁻¹, and maintains an impressive 95% capacity retention after 2400 cycles at 15 A g⁻¹. The DFT calculations reveal that Zn²⁺ doping lowers the bandgap and migration energy barrier. In-situ XRD, in-situ Raman and XPS elucidate the structural evolution and CEI formation mechanism. This work provides valuable insights for the synergistic modification of cathode and electrolyte towards advanced aqueous zinc ion batteries.