High-energy and fast-charging lithium metal batteries enabled by tuning Li+-solvation via electron-withdrawing and lithiophobicity functionality
Guangzhao Zhang, Tong Zhang, Zhen Zhang, Ruilin He, Qingrong Wang, Shang‐Sen Chi, Yanming Cui, Meng Gu, Zhongbo Liu, Jian Chang, Chaoyang Wang, Kang Xu, Yonghong Deng
Abstract
The solvent fluorination almost always improves electrochemical stability of electrolytes against both lithium anodes and high-voltage cathodes in lithium metal batteries. However, how exactly fluorination affects Li+-solvation and interphasial chemistries remains unclear, hindering rational design of electrolytes and interphases with both wide electrochemical stability window and fast ion transport kinetics that are required for energy-dense and fast-charging LMBs. Here we introduce the trifluoromethylation (-CF3) at one end of 1,2-dimethoxyethane and generate 1,1,1-trifluoro-2-(2-methoxyethoxy) ethane, which as a single solvent of electrolyte simultaneously meets energy-dense and fast-charging requirements when dissolving 2 M lithium bis(fluorosulfonyl)imide. Beside the electron-withdrawing effect of -CF3, we find that its lithiophobic nature against Li+ significantly alters the solvation structures, which favors the formation of anion-dominated clusters that lead to superior interphasial chemistries in layered structure and fast Li+ transport kinetics. In such electrolyte, lithium metal batteries constructed with 50-μm-thin Li||high-loading-NMC811 in both coin and pouch cell configurations achieve >400 cycles under fast-charging condition, and >100 cycles in 14-Ah-level industrial pouch cell with a high energy density over 510 Wh kg−1 at cell-level. The electrochemical stability window and Li+ transport limit the energy-dense and fast-charging capability of lithium metal batteries. Here, authors report a trifluoride ether-based electrolyte to stabilize energy-dense lithium metal batteries under high current rates.