Localized High-Concentration Binary Salt Electrolytes with Suppressed Li 2 S x Solubility to Achieve Stable Li–S Pouch Cells with High Sulfur-Loading Cathodes under Lean Electrolyte Conditions

作者：Jiali Liu, Arnab Ghosh, Shinji Kondou, Shanglin Li, Kazuhide Ueno, Kaoru Dokko, Masayoshi Watanabe · 发表于：ACS Applied Energy Materials · 年份：2025 · DOI：10.1021/acsaem.4c02712 · 被引用次数：9 · 研究领域：Advanced Battery Materials and Technologies、Advancements in Battery Materials、Advanced Battery Technologies Research

The endurance of lithium–sulfur (Li–S) cells depends on the stability of lithium (Li) metal anodes and their consistent efficiency during extended Li dissolution and deposition cycles. Electrolytes containing Li[N(SO 2 F) 2 ] (Li[FSA]) have shown potential in enhancing Li anode reversibility by promoting the formation of a favorable inorganic-rich solid-electrolyte interphase (SEI) on the Li metal electrode. However, the use of Li[FSA] as the primary electrolyte salt in Li–S batteries is hindered by the spontaneous side reactions of [FSA] − anions with soluble lithium-polysulfides (Li 2 S x, 2 ≤ x ≤ 8). To overcome this challenge, we have developed a localized high-concentration electrolyte (LHCE) with reduced Li 2 S x solubility, composed of Li[TFSA 0.8 LiFSA 0.2 ] ([TFSA]: [N(SO 2 CF 3 ) 2 ]) binary salts dissolved in sulfolane (SL) and diluted by 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (HFE). This LHCE solution demonstrates superior stability of [FSA] − anions, due to the restricted dissolution of Li 2 S x within the LHCE. We experimentally evaluated the critical factors affecting reversibility of Li dissolution/deposition in electrolytes containing Li[TFSA 0.8 LiFSA 0.2 ]. Increased salt concentration, combined with HFE dilution, widens the reduction potential gap between the anion and Li +, which thermodynamically promotes anion reduction, controls SEI composition, and improves Li reversibility. We demonstrate the operation of a Li–S pouch cell under pra...