Enhancing Zn2+ Storage Performance by Constructing the Interfaces Between VO2 and Co-N-C Layers

Abstract

Vanadium oxides have aroused attention as cathode materials in aqueous zinc-ion batteries (AZIBs) due to their low cost and high safety. However, low ion diffusion and vanadium dissolution often lead to capacity decay and deteriorating stability during cycling. Herein, vanadium dioxides (VO₂ ) nanobelts are coated with a single-atom cobalt dispersed N-doped carbon (Co-N-C) layer via a facile calcination strategy to form Co-N-C layer coated VO₂ nanobelts (VO₂ @Co-N-C NBs) for cathodes in AZIBs. Various in-/ex situ characterizations demonstrate the interfaces between VO₂ layers and Co-N-C layers can protect the VO₂ NBs from collapsing, increase ion diffusion, and enhance the Zn²⁺ storage performance. Additional density functional theory (DFT) simulations demonstrate that Co─O─V bonds between VO₂ and Co-N-C layers can enhance interfacial Zn²⁺ storage. Moreover, the VO₂ @Co-N-C NBs provided an ultrahigh capacity (418.7 mAh g^-1 at 1 A g^-1 ), outstanding long-term stability (over 8000 cycles at 20 A g^-1 ), and superior rate performance.

Keywords: Co-N-C layer; cathode; energy storage mechanisms; single-atom carbon coated VO2 nanobelts; zinc-ions batteries.