Achieving the directional zinc ions transport in belt-like orderly arranged vanadium dioxide cathode material

Abstract

Developing stable, high-capacity cathodes for zinc-ion batteries represents a key step toward accelerating their commercialization. However, the considerably enlarged ionic radius of hydrated Zn2+ induces sluggish reaction kinetics and poor structural durability of the cathode materials. Herein, we propose to achieve directional Zn2+ transport and shorten Zn2+ diffusion pathways by fabricating belt-like orderly arranged VO2 (B-VO2). Relative to conventional VO2 (C-VO2) with inherently sluggish ion transport dynamics, the prepared B-VO2 exhibits favorable rapid Zn2+ diffusion along the c-axis within the (110) crystallographic plane, with its diffusion coefficient ranging from 10-8 to 10-10 cm2 s-1, which is 2 orders of magnitude higher than that of C-VO2 (10-10 to 10-12 cm2 s-1). The assembled aqueous zinc-ion batteries deliver an impressive initial specific capacity (357.6 mAh g-1 at 0.2 A g-1), with 86.1% capacity retention after 4000 cycles at 5 A g-1, which is significantly superior to the cycling performance of C-VO2 (52.6% capacity retention after 1500 cycles at 5 A g-1). The pouch cell delivers a high initial discharge capacity of 193.8 mAh g-1 at 1 A g-1 and maintains 90.1% of its initial capacity after 100 stable cycles. The results demonstrate that regulating the structural arrangement of vanadium-based cathode materials is an effective strategy to boost ion transport kinetics for high-performance aqueous zinc-ion batteries.