Constructing inorganic-rich solid electrolyte interphase via abundant anionic solvation sheath in commercial carbonate electrolytes

Lithium (Li) metal anode coupled with high-voltage cathode is critical for realizing high-energy storage. However, the organic-dominated solid electrolyte interphase (SEI) originating from carbonate electrolytes undergoes continuous cracking/reformation during cycling, leading to severe Li dendrite growth that hinders its practical application. Herein, we report an extremely soluble ionic liquid salt of pyridinium trifluoroacetate for constructing inorganic-rich SEI on Li in commercial carbonate electrolytes. Pyridinium cations (Py+) could be attached to the negatively-charged surface of Li due to electrostatic interaction and thereafter be decomposed into Li+-conductive nitrogen-containing components. Moreover, benefiting from the strong coordination of carbonyl (CO) and Li+, trifluoroacetate anions (TFA−) can prompt the dissolution of lithium nitrate (LiNO3) in carbonate electrolytes, thereby tuning the Li+ solvated shell. The formation of distinct solvation shell involving abundant anions is experimentally and theoretically demonstrated, which favors rapid desolvation kinetics. In addition, combined effect of additives facilitates the formation of additive-derived LiF-Li3N enhanced inorganic-rich SEI, significantly reducing the Li+ diffusion energy barrier and promoting compact chunky Li deposition. A thin and dense cathode electrolyte interphase (CEI) layer is generated in designed electrolyte and restrains dissolution of transition-metals. Consequently, superior cycling and rate performance of Li||NCM523 cells is achieved, confirming the enhanced stability. [Display omitted] •The ionic liquid salt of pyridinium trifluoroacetate is innovatively utilized as the carbonate electrolyte additive.•The cations regulate Li deposition and the anions promote the dissolution of insoluble LiNO3.•The formation of distinct solvation shell involving abundant anions is conducive to the rapid desolvation kinetics of Li+.•The inorganic-rich SEI significantly reduces the Li+ diffusion energy barrier and enables the compact Li deposition.