Designed Construction of Bifunctional Interphase Preactivated via Over‐Discharge Strategy Toward Stable Lithium–Sulfur Batteries

Abstract Significant challenges remain to be overcome for practical application of high energy density lithium–sulfur batteries including poor cyclability induced by “the shuttle effect”, parasitic reactions, and uncontrollable growth of lithium dendrites. To overcome these problems, a bifunctional solid electrolyte interphase layer is successfully constructed by employing an over‐discharge pre‐activation strategy to in situ induce a reduction reaction between lithium anode and functional electrolyte additive, 3,3,3‐trifluoropropylene carbonate (TFPC). TFPC exhibits lower electron affinity and LUMO energy levels, facilitating its reaction with lithium metal to form SEI films with high mechanical robustness and ionic conductivity, resulting in uniform and fast lithium deposition/stripping and reduced parasitic reactions between lithium polysulfides and the lithium anode. As a result, the overall performance of lithium–sulfur batteries is improved. The decomposition pathway and action mechanism of TFPC are systematically and deeply revealed by density functional theory (DFT) calculations, ab initio molecular dynamics (AIMD) simulations, and detailed experimental results. The aim of this study is to provide a feasible avenue for lithium–sulfur battery interfacial protection and to solve the imminent lithium–sulfur battery problem through in‐depth investigation of the bonding chemistry in TFPC molecules and the clever design of interfacial reactions.