Wang Min, Li Mengjie, Wu Junru, Meng Yuefeng, Hao Jing, Zhou Dong, Han Cuiping, Li Baohua
Institute of Materials, Research Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China.
School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China.
Adv Mater. 2025 May 13:e2502076. doi: 10.1002/adma.202502076.
The stable operation of lithium metal batteries (LMBs) at high voltages is currently limited by the performance of conventional electrolytes. Fluoroethylene carbonate (FEC) exhibits unique physicochemical properties that positively impact interfacial chemistry, positioning it as a promising candidate to enhance the performance of LMBs. However, FEC is prone to the formation of corrosive HF under high voltage, which leads to the degradation of electrode interface. In this study, a hybrid gel polymer electrolyte (HGPE) based on pure FEC solvent with pentafluorophenyl methacrylate (PFPMA) monomer is presented to extend the voltage operating range. The PFPMA monomer forms a mixed-layer solid electrolyte interphase with lithium difluoro(oxalato)borate (LiDFOB) on electrode surface, effectively inhibiting the decomposition of FEC. The triangular synergistic strategy involving FEC, PFPMA, and polymer segments improves the transport of Li ions in FEC, achieving a high Li transference number of 0.87. The designed electrolyte demonstrates good compatibility with Li metal and stabilizes LiNiCoMnO (NCM811) cathodes. As a result, the Li||NCM811 battery based HGPE exhibits a capacity retention of 83.4% after 300 cycles and 74.2% after 400 cycles, under a cut-off voltage of 4.5 V. This study provides a promising strategy for the development of GPE for high-voltage LMBs applications.
锂金属电池（LMBs）在高电压下的稳定运行目前受到传统电解质性能的限制。氟代碳酸乙烯酯（FEC）具有独特的物理化学性质，对界面化学有积极影响，使其成为提高LMBs性能的有前途的候选物。然而，FEC在高电压下容易形成腐蚀性的HF，这会导致电极界面的降解。在本研究中，提出了一种基于纯FEC溶剂与甲基丙烯酸五氟苯酯（PFPMA）单体的混合凝胶聚合物电解质（HGPE），以扩展电压工作范围。PFPMA单体在电极表面与二氟草酸硼酸锂（LiDFOB）形成混合层固体电解质界面，有效抑制FEC的分解。涉及FEC、PFPMA和聚合物链段的三角协同策略改善了Li离子在FEC中的传输，实现了0.87的高Li迁移数。所设计的电解质与锂金属具有良好的兼容性，并稳定了LiNiCoMnO（NCM811）阴极。结果，基于HGPE的Li||NCM811电池在4.5 V的截止电压下，300次循环后容量保持率为83.4%，400次循环后为74.2%。本研究为开发用于高压LMBs应用的凝胶聚合物电解质提供了一种有前途的策略。
