Tri-anions regulated solvation structure in intrinsically nonflammable phosphate-based electrolytes for stable lithium metal batteries

Abstract

• A simple Tri-anions strategy ensures triethyl phosphate (TEP) serves as a mono-solvent in lithium metal batteries (LMB) in the case of normal concentration to achieve intrinsically nonflammable. • The optimal anion molar ratio which can effectively regulate the solvation structure was revealed. • Uniformly Li deposition behavior was achieved in phosphate-based electrolytes which is incompatible with Li. The cycling instability and unsafety blocked the application of lithium metal batteries (LMB). Nonflammable solvents are hoped to improve the security of LMB; however, employing these solvents will irreversibly damage the cycling stability owing to incompatibility with Li metal. Herein, we regulated solvation structures in triethyl phosphate (TEP) through a simple Tri-anions strategy to achieve cycling stability and safety of LMB. Molecular dynamic simulation demonstrates that the solvation structure is well adjusted which can induce a powerful inorganic-rich solid electrolyte interface (SEI) to circumvent parasitic reactions between TEP solvents and Li anode as well as promote uniformly Li deposition. As a result, Li/LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM 811) cell has a capacity retention of 98.6 % after 300 cycles and Li/LiFePO 4 (LFP) cell retains 75 % after 700 cycles. The novel electrolyte is expected to offer a promising approach for improving high safety and high-electrochemical-performance LMB. The intrinsically nonflammable electrolytes and stable lithium anodes are achieved through a simple Tri-anions strategy with a specific molar ratio to regulate solvation structure.