Selenium-doped VO2 cathode with enhanced kinetics towards stable zinc–vanadium pouch batteries

Abstract

For high-loading vanadium oxide cathodes in zinc-ion pouch cells, the issues of electron distribution and reaction kinetics are the key constraints on their cycle life and practical application. This study effectively enhances the electronic conductivity and Zn²⁺ diffusion kinetics of VO₂ cathode materials through a selenium doping strategy, successfully constructing highly stable zinc–vanadium pouch batteries. The introduction of Se²⁻ not only expands the lattice spacing of VO₂ and optimizes charge distribution, but also facilitates Zn²⁺ migration by lowering its diffusion barrier, consequently boosting the Zn-storage capability of the electrode. The prepared VO₂-Se2 cathode exhibits a high specific capacity of 432.3 mAh g⁻¹ at 0.3 A g⁻¹ and maintains 271.3 mAh g⁻¹ after 5000 cycles at 5 A g⁻¹, demonstrating excellent zinc storage capacity. More significantly, the pouch battery assembled with the cathode retains a capacity of 192 mAh g⁻¹ after 450 cycles at 1 A g⁻¹, with a remarkable retention of 99%, highlighting its considerable potential for commercial deployment. The present approach establishes a practical material design tactic for developing high-capacity, highly stable aqueous zinc–vanadium pouch cells.