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Designing Anion-Derived Solid Electrolyte Interphase in a Siloxane-Based Electrolyte for Lithium-Metal Batteries

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journal contribution
posted on 07.06.2022, 15:36 by Jianyang Wu, Tianyi Zhou, Bing Zhong, Qian Wang, Wen Liu, Henghui Zhou
The rational electrolyte design with weak solvation is regarded as an effective way to regulate the electrolyte/electrode interface (SEI) that profoundly affects the performance of Li-metal batteries. Herein, we propose a newly developed siloxane-based weakly solvating electrolyte (SiBE) with contact ion pairs (CIPs) or aggregates (AGGs) dominating the solution structure, which enables the dendrite-free Li deposition and long cycle stability of Li-metal batteries. By altering the combination of Li salts, the SiBE leads to the formation of an inorganic anion-derived solid electrolyte interphase, which is highly stable and Li+-conductive. Based on SiBE, the Li||LiFePO4 (LFP) full cell can stably cycle for 1000 cycles at a 2C rate with a capacity retention of 76.9%. Even with a limited Li-metal anode, it can maintain a capacity retention of 80% after 110 cycles with a high average Coulombic efficiency of 99.8%. This work reveals that siloxane can be a promising solvent to obtain weakly solvating electrolytes, which opens a new avenue for SEI composition regulation of Li-metal batteries.

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