Dual functions of Lewis acid–base synergy and ZnSe-CoSe2 heterojunctions toward stable solid-state lithium-sulfur batteries

Abstract

Solid-state lithium-sulfur batteries (SSLSBs) are considered promising next-generation energy storage systems due to their high energy density and improved safety. However, their practical application has been hindered by sluggish redox kinetics during sulfur/Li₂S interconversion and the polysulfide shuttle effect. Herein, we introduce a transition metal selenide heterostructure (TMSe: ZnSe-CoSe₂) as an efficient catalytic material to enhance bidirectional sulfur conversion. The constructed TMSe heterojunction features abundant heterointerfaces that significantly promote lithium-ion (Li⁺) diffusion while simultaneously catalyzing both the sulfur reduction reaction (SRR) and the Li₂S oxidation reaction. Furthermore, CoSe₂ acts as a Lewis acid site, exhibiting strong affinity and effective chemisorption toward polysulfides, thus suppressing the shuttle effect. As a result, the PVDF-based SSLSB with a sulfur cathode hosted in the TMSe@nitrogen-doped porous carbon (TMSe@NC) delivers high specific capacities of 1526.7 and 397.2 mAh g⁻¹ at 0.1 and 1.0 C, respectively. Remarkably, the cell exhibits a capacity retention of 60.6% after 80 cycles at 0.2 C and retains a reversible capacity of 503.9 mAh g⁻¹ after 100 cycles at 0.5 C. This study provides valuable insights into the design of high-performance cathodes for PVDF-based SSLSBs operating under near-ambient temperature conditions.