Local Electric Field Accelerates Zn2+ Diffusion Kinetics for Zn-V Battery

Abstract

Vanadium-based aqueous zinc-ion batteries (AZIBs) exhibit significant potential for large-scale energy storage applications, attributed to their inherent safety characteristics. Addressing the slow transport kinetics of divalent Zn²⁺ within the cathode lattice, thereby enhancing the rate capability and stability, is essential for the Zn-V battery system. In this study, a local electric field (LEF) strategy is introduced to accelerate the Zn²⁺ diffusion by creating abundant oxygen vacancies (Ov) in V₂O₅. Comprehensive characterization and density functional theory (DFT) calculations reveal the formation of the Ov induced atomic-level donor-acceptor couple configuration, verify and visualize the LEF. The fabricated LEF-enhanced vanadium oxide (LEF-VO) exhibits exceptional rate capability, achieving 338.3 mA h g⁻¹ at a current density of 10 A g⁻¹, and maintaining 66.4% of its capacity over a range from 0.2 to 20 A g⁻¹. Furthermore, the influence of the LEF on expediting Zn²⁺ diffusion kinetics is elucidated, correlating to the electrical force. This novel LEF approach offers valuable insights for advancing high-rate cathode materials.