The electrochemistry of stable sulfur isotopes versus lithium

• 成果类型: Article
• 署名作者: Li, Xue-Ting; Zhao, Yao; Zhu, Yu-Hui; Wang, Wen-Peng; Zhang, Ying; Wang, Fuyi; Guo, Yu-Guo; Xin, Sen; Bai, Chunli
• 署名单位: Chinese Academy of Sciences; Institute of Chemistry, CAS; Chinese Academy of Sciences; University of Chinese Academy of Sciences, CAS; Chinese Academy of Sciences; Institute of Chemistry, CAS
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-14686
• DOI: 10.1073/pnas.2316564121
• 发表日期: 2024-04-02
• 关键词: total-energy calculations; polysulfides; raman; mechanism; shuttle

摘要

Sulfur in nature consists of two abundant stable isotopes, with two more neutrons in the heavy one (S-34) than in the light one (S-32). The two isotopes show similar physicochemical properties and are usually considered an integral system for chemical research in various fields. In this work, a model study based on a Li-S battery was performed to reveal the variation between the electrochemical properties of the two S isotopes. Provided with the same octatomic ring structure, the cyclo-(34)S8 molecules form stronger S-S bonds than cyclo-(32)S8 and are more prone to react with Li. The soluble Li polysulfides generated by the Li-S-34 conversion reaction show a stronger cation-solvent interaction yet a weaker cation-anion interaction than the S-32-based counterparts, which facilitates quick solvation of polysulfides yet hinders their migration from the cathode to the anode. Consequently, the Li-S-34 cell shows improved cathode reaction kinetics at the solid-liquid interface and inhibited shuttle of polysulfides through the electrolyte so that it demonstrates better cycling performance than the Li-S-32 cell. Based on the varied shuttle kinetics of the isotopic-S- based polysulfides, an electrochemical separation method for S-34/S-32 isotope is proposed, which enables a notably higher separation factor than the conventional separation methods via chemical exchange or distillation and brings opportunities to low-cost manufacture, utilization, and research of heavy chalcogen isotopes.