Selective adsorption-catalytic action of spinel sulfur reduction catalyst based on geometric structure regulation on lithium polysulfide

Spinel-structured catalysts demonstrate significant potential for sulfur reduction reaction (SRR) catalysis in lithium-sulfur batteries (LSBs) owing to their geometrically tunable active sites, yet precise structural optimization for simultaneous enhancement of lithium polysulfides (LiPSs) adsorption and catalytic conversion remains challenging. This study addresses this gap through strategic cation occupancy regulation in Co x Mn 3-x O 4 spinels, establishing a dual-active-site system comprising tetrahedral Co 3+ (Td) and octahedral Mn 3+ (Oh) centers that drive selective LiPSs electrocatalysis via geometric synergy. Theoretical and experimental analyses confirm Co 1.2 Mn 1.8 O 4 as the optimal configuration, where optimized Td/Oh Site Distribution Enables: (i) stable covalent Co-S bonding for strong LiPSs adsorption at Td sites, and (ii) dynamic Mn³⁺ (Oh)-S d -p orbital coupling via delocalized d² electrons that critically reduce LiPSs desorption energy barriers (ΔG ≤ 0.82 eV). Leveraging this complementary functionality, a Co 1.2 Mn 1.8 O 4 -embedded carbon nanofiber interlayer delivers exceptional cycling stability—achieving 400 cycles at 1 C with 74.6 % capacity retention. This work extends the application of spinel-type SRR catalysts to high-performance lithium-sulfur batteries.