Precipitate-Driven Electrochemical Interactions in Lithium–Sulfur Batteries

Abstract Lithium–sulfur (Li–S) batteries combine high specific energy with complex interfacial chemistry, where the dissolution and precipitation of electronically insulating sulfur species define charge transfer pathways. Although transport, shuttle effects, and morphology have been extensively studied, the mechanisms that govern charge transfer through and around precipitates remain poorly understood. This viewpoint integrates experimental and theoretical understanding to explain how substrate–electrolyte interactions, nucleation dynamics, and evolving Li2S topology govern the transition from passivating two-dimensional films to percolated three-dimensional networks that sustain reaction fronts. Electronic defect transport through polaronic conduction and solution-phase electron shuttling by redox mediators are identified as key mechanisms that preserve activity within insulating deposits. Operating conditions and electrolyte composition further affect precipitation modes, determining local kinetics and overall charge transfer resistance. These insights provide a mechanistic framework for quantifying and controlling precipitation-induced charge transfer resistance and morphological evolution in Li–S batteries.