Microemulsion Engineering Reconciles Propylene Carbonate Electrolytes and Graphite Anodes for All-Climate Lithium-Ion...

Propylene carbonate (PC)-based electrolytes are promising for all-climate lithium-ion batteries due to their wide liquid range. However, detrimental Li⁺-PC co-intercalation causes severe graphite (Gr) anode exfoliation, remaining the biggest barrier for their practical application. Although the issue can be mitigated via solvation regulation, complex interfacial chemistry limits long-term cycling ability. Herein, we designed a PC-based microemulsion electrolyte to achieve PC/Gr compatibility through interfacial manipulation. Specifically, insoluble glyceryl monostearate (GMS) and amphiphilic tetrahydrofuran (THF) are introduced into the PC-based electrolyte. GMS self-assembles in THF to form core-shell GMS@THF micelles dispersed in the continuous PC electrolyte medium. This microemulsion structure generates abundant liquid-liquid interfacial tension at micelle/electrolyte interfaces, spontaneously directing micelles to the electrode interfaces during operation. At the Gr anode, adsorbed GMS@THF micelles leverage solvophobic effects to synergistically form PC-poor Li⁺ solvation sheaths and block free PC, effectively suppressing detrimental PC co-intercalation. This design enables Li||Gr cells achieve a high initial Coulombic efficiency of 92.8% and supports 1 Ah Gr||LiFePO₄ pouch cells to operate over 4000 cycles. Remarkably, the pouch cells work well across extreme temperatures (-40∼100 °C cycling; -60∼100 °C operation), demonstrating exceptional all-climate capability. This microemulsion engineering establishes a universal paradigm for optimizing electrolyte/electrode interphases in the PC/Gr system.