Fei Yue, Li Matthew, Li Zhenfeng, Guan Dichang, Jia Wenting, Zhang Hao, Amine Khalil, Li Ge
Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta, T6G 1H9, Canada.
Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 Cass Ave., Lemont, IL, 60439, USA.
Adv Mater. 2025 Jul 9:e2507459. doi: 10.1002/adma.202507459.
Lithium bis(trifluoromethane)sulfonimide (LiTFSI) is widely used in lithium-sulfur (Li-S) battery electrolytes due to its stability with lithium polysulfides (LiPSs) and moderate compatibility with lithium metal anodes. However, LiTFSI presents environmental concerns due to its association with per- and polyfluoroalkyl substances (PFAS), which are environmentally persistent and potentially toxic, raises sustainability concerns. This research also reveals that LiTFSI limits sulfur redox reactions (SRRs), making it less effective than other lithium salts. Additionally, some salts previously considered incompatible with Li-S systems due to their reactivity with LiPSs are demonstrated to perform effectively. For the first time, a protective, porous cathode electrolyte interphase (CEI) formed in situ through reactions between salt anions and LiPS is reported. The cells delivered a high specific capacity of 1230.8 mAh g at 0.05 C with a sulfur loading of ≈6 mg cm, limited lithium anode, maintaining a capacity retention of 76.2% after 100 cycles at 0.1 C. Under harsh conditions, such as high sulfur loading, lean electrolyte conditions (3 µL mg), and in anode-free cells, the cells continued to deliver outstanding capacity. This work provides valuable guidelines for understanding and selecting lithium salts to advance electrolyte design for Li-S batteries.
双（三氟甲烷）磺酰亚胺锂（LiTFSI）因其与多硫化锂（LiPSs）的稳定性以及与锂金属负极的适度兼容性，而被广泛应用于锂硫（Li-S）电池电解质中。然而，LiTFSI因其与全氟和多氟烷基物质（PFAS）相关联而引发环境问题，PFAS在环境中具有持久性且可能有毒，这引发了可持续性方面的担忧。该研究还表明，LiTFSI限制了硫氧化还原反应（SRRs），使其比其他锂盐的效果更差。此外，一些先前因与LiPSs反应而被认为与Li-S系统不兼容的盐，经证明具有有效性能。首次报道了通过盐阴离子与LiPS之间的反应原位形成的一种保护性多孔正极电解质界面（CEI）。在硫负载量约为6 mg/cm²、锂负极受限的情况下，该电池在0.05 C时具有1230.8 mAh/g的高比容量，在0.1 C下循环100次后容量保持率为76.2%。在高硫负载、贫电解质条件（3 μL/mg）以及无负极电池等苛刻条件下，该电池仍能持续提供出色的容量。这项工作为理解和选择锂盐以推进Li-S电池的电解质设计提供了有价值的指导方针。
