Yan Shuaishuai, Liu Hao, Lu Yang, Feng Qingqing, Zhou Hangyu, Wu Yuhao, Hou Wenhui, Xia Yingchun, Zhou Haiyu, Zhou Pan, Song Xuan, Ou Yu, Liu Kai
State Key Laboratory of Chemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China.
Hefei Institute for Public Safety Research, Tsinghua University, Hefei 230601, Anhui, China.
Sci Adv. 2025 Jan 31;11(5):eads4014. doi: 10.1126/sciadv.ads4014.
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 LiO-rich solid electrolyte interphase. Therefore, the stable cycling of more than 1650 cycles (Coulombic efficiency, 99.8%) for LiFePO/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.
固态聚合物电解质存在聚合物主导的锂溶剂化结构问题，导致电解质/电极界面不稳定，电池性能下降。在此，我们设计了一类选择性氟化芳族锂盐（SFALS）作为单一导电锂盐，以调节全固态锂金属电池的溶剂化结构和界面化学。通过调整阴离子结构，削弱了锂-聚醚耦合，增强了锂-阴离子配位。SFALS与聚合物基体之间的氢键诱导了一种特殊的“三联体”型溶剂化结构，提高了电解质的均匀性和机械强度，并促进了超薄且坚固的富LiO固态电解质界面的形成。因此，LiFePO/Li半电池实现了超过1650次循环的稳定循环（库仑效率99.8%），全电池实现了580次循环（容量保持率97.4%）。这种分子工程策略可为全固态锂金属电池实际应用中功能性锂盐的进一步发展提供启发。
