Highly Soluble Lithium Nitrate-Containing Additive for Carbonate-Based Electrolyte in Lithium Metal Batteries

While lithium nitrate (LiNO3) is widely utilized as an electrolyte additive in ether-based electrolytes for stable lithium deposition, use of LiNO3 in conventional carbonate-based electrolytes is very limited due to the poor solubility of LiNO3 in the carbonate-based electrolytes. Herein, a new LiNO3-containing electrolyte additive which is very soluble in carbonate-based electrolytes, 1-trimethylsilyl imidazole lithium nitrate adduct (TMSILN), has been synthesized by a simple method. The electrochemical performance is significantly improved in Li/Li and NCM622/Li cells with TMSILN additive containing electrolyte. Our extensive investigations reveal that the deposited lithium metal in the TMSILN additive-containing electrolyte has a circular morphology with a very thin (∼5 nm) surface film containing lithium nitrate decomposition products such as Li3N and LiNxOy. The improved electrochemical performance can be ascribed to the favorable features of the SEI and morphology of the deposited lithium in the presence of the TMSILN additive.