A functional lithium salt for polymerization-free DOL electrolytes in low-temperature or high-rate Li metal batteries

1, 3-Dioxolane (DOL), as an ideal electrolyte solvent for lithium metal batteries, exhibits excellent low-temperature performance and fast-charging potential. However, its practical application is severely hindered by Lewis acid-catalyzed ring-opening polymerization. Herein, a theoretical framework is established to evaluate the ring-opening polymerization tendency of cyclic ethers. The results reveal that the pronounced susceptibility of DOL to such polymerization stems from its combination of high ring-opening strain energy and strong nucleophilicity. Therefore, we propose an “Lewis acid trapping” strategy and synthesize a strongly Lewis-basic lithium salt additive, lithium tetrakis[(1,3-dioxolan-4-yl)methoxy]aluminate (LAD). It sequesters Lewis acids to suppress polymerization while regulating the solvation structure to induce a LiF-rich, polyether-free solid electrolyte interphase (SEI). This enables lithium metal anodes to deliver a high Coulombic efficiency of 99.30%, and the symmetric cell further exhibits stable plating/stripping over 4000 h at 0.5 mA cm −2 . Consequently, Li/LE-LAD/LiFePO 4 full cells demonstrate superior low-temperature (−30 °C) and rate performance (20C). As a practical validation, a 1.3 Ah Li// LiFePO 4 pouch cell retains 97.9% capacity over 120 cycles following 30 days of storage. The theoretical prediction framework and active inhibition strategy proposed in this work offer a solution to uncontrolled polymerization in cyclic-ether-based electrolytes.