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 nextgeneration energy storage systems due to their high energy density and improved safety.However, their practical application has been hindered by sluggish redox kinetics during the sulfur/Li₂S interconversion and the polysulfide shuttle effect. Herein, we introduce a transition metal selenide heterostructure (TMSe: ZnSe-CoSe 2 ) 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 Li 2 S oxidation reaction. Furthermore, CoSe 2 acts as Lewis's 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 PVDFbased SSLSBs operating under near-ambient temperature conditions.