Formulating a New Electrolyte: Synergy between Low-Polar and Non-polar Solvents in Tailoring the Solid Electrolyte Interface for the Silicon Anode

• Published in: ACS applied materials & interfaces 2021-11, Vol.13 (46), p.55700-55711
• Main Authors: Pan, Si-Yu, Yang, Xue-Rui, Zhou, Yao, Lv, Chao, Deng, Hao-Tian, Guo, Ming-Jia, Chen, Shou-Xiao, Hu, Yi-Yang, Deng, Li, Qiao, Yu, Li, Jun-Tao, Huang, Ling, Yang, Yong, Sun, Shi-Gang
• Format: Article
• Language: English
• Subjects: Surfaces, Interfaces, and Applications
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.1c16827

Currently, lithium-ion batteries (LIBs) are assembled with polar electrolytes; thus, resulting SEI layers are dominated with organics. Herein, a low-polarity electrolyte is formulated with a low-polarity solvent (tetraethyl silicate, TEOS) and a non-polar inert shielding co-solvent (cyclohexane, CYH); solvation behaviors of lithium salt are investigated. The use of such a low-polarity solvent is found to improve the fraction of anions in the solvation sheath of Li+, and the presence of the non-polar co-solvent further shields the reductive decomposition of the solvent on the anode. The resulting SEI layer is relatively rich in LiF and has a 3D cross-linked Si–O network as a skeleton from the decomposition of TEOS molecules, which is more robust to tolerate the damage from the volume expansion of silicon. A Si-nanoparticle-based anode in such a low-polarity electrolyte delivers a capacity as high as 1491 mAh g–1 after 200 cycles, outperforming those in the commercial polar electrolytes.