Conductive and Catalytic Triple‐Phase Interfaces Enabling Uniform Nucleation in High‐Rate Lithium–Sulfur Batteries

TLDR

Rechargeable lithium–sulfur batteries have attracted tremendous scientific attention owing to their superior energy density, yet sulfur electrochemistry involves multielectron redox reactions and complex phase transformations that dominate performance. The study proposes a triple‑phase interface among electrolyte/CoSe₂/graphene to provide strong chemisorption, high electrical conductivity, and superb electrocatalysis of polysulfide redox reactions. By integrating CoSe₂ with graphene in the separator, the authors create a triple‑phase interface that enhances polysulfide adsorption, conductivity, and catalytic activity. This interface improves lithium polysulfide kinetics, promotes uniform Li₂S nucleation, and enables an ultrahigh‑rate cycle at 6.0 C with 916 mAh g⁻¹ initial capacity and 459 mAh g⁻¹ after 500 cycles, even at high sulfur loading.

Abstract

Abstract Rechargeable lithium–sulfur batteries have attracted tremendous scientific attention owing to their superior energy density. However, the sulfur electrochemistry involves multielectron redox reactions and complicated phase transformations, while the final morphology of solid‐phase Li 2 S precipitates largely dominate the battery's performance. Herein, a triple‐phase interface among electrolyte/CoSe 2 /G is proposed to afford strong chemisorption, high electrical conductivity, and superb electrocatalysis of polysulfide redox reactions in a working lithium–sulfur battery. The triple‐phase interface effectively enhances the kinetic behaviors of soluble lithium polysulfides and regulates the uniform nucleation and controllable growth of solid Li 2 S precipitates at large current density. Therefore, the cell with the CoSe 2 /G functional separator delivers an ultrahigh rate cycle at 6.0 C with an initial capacity of 916 mAh g −1 and a capacity retention of 459 mAh g −1 after 500 cycles, and a stable operation of high sulfur loading electrode (2.69–4.35 mg cm −2 ). This work opens up a new insight into the energy chemistry at interfaces to rationally regulate the electrochemical redox reactions, and also inspires the exploration of related energy storage and conversion systems based on multielectron redox reactions.