Hetero-interface constructs ion reservoir to enhance conversion reaction kinetics for sodium/lithium storage

Abstract

Developing high-capacity electrode materials is most vital to high-energy rechargeable batteries. The conversion reaction-based anode materials deliver substantially higher theoretical capacities in respect to intercalation-based materials. However, the sluggish conversion reaction kinetics is a big obstacle to deliver high practical capacity and rate capability, which is particularly severe for sodium storage. Herein, we implement an interface engineering approach by designing hetero-interfaces to enhance conversion reaction. As a proof of concept, Sb2S3-SnS2 hetero-nanostructures are synthesized and show greatly improved electrochemical performance in terms of specific capacity and rate capability. The DFT calculations reveal that the hetero-interfacial electric field prompts sodium ions pump into the interfaces, which greatly reduces the activation barrier and hence accelerates reaction kinetics. The Sb2S3-SnS2 hetero-interface serves therefore as a “reservoir” and fast diffusion channel for sodium or lithium ions. The obtained results provide important insights into engineering efficient hetero-nanostructures towards fast conversion reaction kinetics for rechargeable batteries.