Design of a cationic accelerator enabling ultrafast ion diffusion kinetics in aqueous zinc-ion batteries

Abstract

Aqueous zinc-ion batteries are highly favored for grid-level energy storage owing to their low cost and high safety, but their practical application is limited by slow ion migration. To address this, a strategy has been developed to create a cation-accelerating electric field on the surface of the cathode to achieve ultrafast Zn²⁺ diffusion kinetics. By employing electrodeposition to coat MoS₂ on the surface of BaV₆O₁₆·3H₂O nanowires, the directional built-in electric field generated at the heterointerface acts as a cation accelerator, continuously accelerating Zn²⁺ diffusion into the active material. The optimized Zn²⁺ diffusion coefficient in CC@BaV₆O₁₆·3H₂O@MoS₂ (7.5 × 10⁻⁸ cm² s⁻¹) surpasses that of most reported V-based cathodes. Simultaneously, MoS₂ serving as a cathodic armor extends the cycling life of the Zn-CC@BaV₆O₁₆·3H₂O@MoS₂ full batteries to over 10000 cycles. This work provides valuable insights into optimizing ion diffusion kinetics for high-performance energy storage devices.