Solvent-derived inorganic F and N-rich solid electrolyte interface for stable lithium metal batteries

Abstract

Extensive research has focused on the lithium (Li) metal anode, but progress in developing this technology has been hindered by the formation of lithium dendrites and their irreversible effects. In this study, an inorganic LiF-Li3N-rich solid electrolyte interface (SEI) is established in ether electrolyte through the direct use of 2,3-difluoro-5-(trifluoromethyl)pyridine (DP) to enable uniform Li deposition and enhance interfacial properties for a stable Li metal anode. Theoretical calculations show that DP has a higher tendency to decompose on lithium metal. An alternative approach involving the inclusion of additional anions into the solvation sheath of Li+ ions using weakly solvating solvents is proposed. During Li plating, DP is reduced to form a LiF and Li3N-rich SEI, resulting in a heterogeneous SEI layer on the Li metal anode surface. This approach allows stable cycling of Li|Li cells for over 1800 h at current densities of 5 mA cm−2 and 15 mAh cm−2. The method presented here has potential significance in the identification of suitable electrolytes for future research on lithium metal anodes.