Selectively fluorinated aromatic lithium salts regulate the solvation structure and interfacial chemistry for all-solid-state batteries
Shuaishuai Yan, Hao Liu, Yang Lu, Qingqing Feng, Hangyu Zhou, Yuhao Wu, Wenhui Hou, Yingchun Xia, Haiyu Zhou, Pan Zhou, Xuan Song, Yu Ou, Kai Liu
Abstract
Solid polymer electrolytes suffer from the polymer-dominated Li + solvation structure, causing unstable electrolyte/electrode interphases and deteriorated battery performance. Here, we design a class of selectively fluorinated aromatic lithium salts (SFALS) as single conducting lithium salts to regulate the solvation structure and interfacial chemistry for all-solid-state lithium metal batteries. By tuning the anionic structure, the Li + -polyether coupling is weakened, and the Li + -anion coordination is enhanced. The hydrogen bonding between the SFALS and polymer matrix induces a special “triad”-type solvation structure, which improves the electrolyte homogeneity and mechanical strength, and promotes the formation of an ultrathin and robust Li 2 O-rich solid electrolyte interphase. Therefore, the stable cycling of more than 1650 cycles (Coulombic efficiency, 99.8%) for LiFePO 4 /Li half cells and 580 cycles (97.4% capacity retention) for full cells is achieved. This molecular engineering strategy could inspire further advancements of functional lithium salts for practical application of all-solid-state lithium metal batteries.