Electrochemically Self-Driven Interfacial Selenium Transfer Reshapes Sulfur Redox Pathway in Lithium-Sulfur Batteries.

Sulfur redox in lithium-sulfur (Li-S) batteries is governed by a multistep liquid-solid conversion network involving soluble polysulfide intermediates and continuously evolving solid-liquid interfaces. Here we identify an electrochemically self-driven interfacial anion-transfer process at a CoPSe-based catalytic interface that reshapes sulfur redox pathway. During discharge, selenium released from the catalyst surface becomes incorporated into sulfur intermediates, redirecting sulfur reduction toward Se-containing species that facilitate bond cleavage, favor shorter-chain intermediates, and accelerate Li2S formation. Meanwhile, partial selenium extraction generates Se-deficient catalytic sites with enhanced polysulfide affinity, promoting intermediate anchoring and liquid-to-solid conversion. Through this coupled evolution of sulfur species and catalytic sites, the interface operates in an operando adaptive mode rather than merely accelerating conventional polysulfide conversion. The resulting Li-S cells deliver 703 mAh g-1 at 5 C with a capacity decay of 0.016% per cycle over 1,000 cycles at 2 C. This work establishes interfacial anion transfer as a route to pathway-level sulfur-redox regulation and adaptive catalyst evolution as a design principle for multistep electrochemical reactions.