Dissolution–Precipitation Dynamics in Ester Electrolyte for High-Stability Lithium Metal Batteries

The dissolution of more LiNO3 in an ester electrolyte is a promising way to stabilize the lithium metal anode in a lithium metal battery. Considering that the maximum solubility of LiNO3 is determined by the dynamic equilibrium between the dissociation (dissolution) of LiNO3 and the recombination (precipitation) of solvated Li+ and NO3–, we report a solvation structure that prevents the recombination of anions and cations by ethylene glycol diacetate with low permittivity mixed with ethylene carbonate as cosolvent. The uncoordinated carbonyl of ethylene glycol diacetate in the solvation structure prevents the recombination of cations and anions. The new dissociation–recombination equilibrium establishes, and the solubility of LiNO3 increases. Therefore, the designed ester electrolyte with high LiNO3 solubility achieves lithium metal batteries with high Coulombic efficiency and long cycling life. Our findings show that the solvents with low permittivity can change the solvation structures of cations and increase the solubility of salts as well by preventing the recombination of anions and cations.