Hollow V2o3@C Microspheres with Electrolyte-Tailored Kinetics for Durable High-Rate Aqueous Zinc-Ion Storage：Zn(Cf3so3)2 vs. Znso4

Abstract

Vanadium oxide-based cathodes for aqueous zinc-ion batteries (AZIBs) face challenges including sluggish reaction kinetics and structural instability. Herein, low-crystalline V2O3@C hollow microspheres were synthesized via a template-free solvothermal method and evaluated in AZIBs using Zn(CF3SO3)2 and ZnSO4 electrolytes. Structural analyses confirmed the hollow architecture composed of interconnected nanoflakes with homogeneous V2O3 and carbon distribution. Electrochemical testing revealed superior performance in Zn(CF3SO3)2, delivering specific capacities of 425 mAh g−1 at 0.5 A g−1 and retaining 237 mAh g−1 after 1,000 cycles at 2 A g−1, outperforming ZnSO4. Kinetic studies attributed this enhancement to pseudocapacitance-dominated charge storage and faster ion diffusion coefficients in Zn(CF3SO3)2. In situ EIS and distribution of relaxation time (DRT) analyses elucidated electrolyte-dependent interfacial dynamics: Zn(CF3SO3)2 facilitated stable interfacial layers with reduced charge-transfer resistance, while ZnSO4 induced unstable deposits. Remarkably, Zn(CF3SO3)2 suppressed vanadium dissolution by 87% compared to ZnSO4. This work establishes triflate electrolytes as a dual-functional strategy for optimizing interfacial kinetics and structural stability in vanadium-based AZIBs, providing critical insights into electrolyte engineering for high-performance energy storage systems.

Keywords: aqueous zinc-ion batteries, V2O3, electrolyte, in situ EIS