Single additive to regulate lithium-ion solvation structure in carbonate electrolytes for high-performance lithium-metal batteries

Lithium nitrate (LiNO3) is widely used to build a stable and highly Li+ conductive solid electrode/electrolyte interface (SEI) for ether-based electrolytes. However, the low solubility of LiNO3 in carbonate-based electrolytes limits its applications in high-voltage lithium-metal batteries. Herein, we report a strategy to introduce NO3− into carbonate electrolytes by a single ionic liquid-type additive, 1-decyl-1-methylpyrrolidine (Py110+) nitrate (IL–NO3–), without additional solubilizers to manipulate Li+ solvation structure. Compared with LiNO3, the weak binding energy between Py110+ and NO3− in IL–NO3– enables carbonate solvent molecules to easily break the IL–NO3– cluster. The NO3− participating in the Li+ solvation sheath can form a robust and highly conductive SEI to promote Li+ transport kinetics. This work provides a realistic reference for the application of an ionic liquid additive to build a stable SEI for advancing the development of lithium-metal batteries.