An Amphiphilic Molecule-Regulated Core-Shell-Solvation Electrolyte for Li-Metal Batteries at Ultra-Low Temperature.

Lithium metal batteries hold great promise for promoting energy density and operating at low temperatures, yet they still suffer from insufficient Li compatibility and slow kinetic, especially at ultra-low temperatures. Herein, we rationally design and synthesize a new amphiphilic solvent, 1,1,2,2-tetrafluoro-3-methoxypropane, for use in battery electrolytes. The lithiophilic segment is readily to solvate Li to induce self-assembly of the electrolyte solution to form a peculiar core-shell-solvation structure. Such unique solvation structure not only largely improves the ionic conductivity to allow fast Li transport and lower the desolvation energy to enable facile desolvation, but also leads to the formation of a highly robust and conductive inorganic SEI. The resulting electrolyte demonstrates high Li efficiency and superior cycling stability from room temperature to -40 °C at high current densities. Meanwhile, anode-free high-voltage cell retains 87 % capacity after 100 cycles.