Ethylene Carbonate Regulated Solvation of Triethyl Phosphate to Enable High-Conductivity, Nonflammable, and Graphite Compatible Electrolyte

Abstract

In the landscape of lithium-ion batteries (LIBs), carbonate-based electrolytes have driven remarkable progress, but persistent safety concerns stemming from their flammability necessitate innovative solutions. This study explores a cost-effective nonflammable cosolvent, triethyl phosphate (TEP), to counter the risk. However, TEP’s strong Li+-coordinating propensity adversely affects graphite (Gr) electrode intercalation. To surmount these challenges, we unveil the competitive coordination behavior of TEP and ethylene carbonate, strategically optimizing TEP’s coordination numbers. This tailored approach culminates in a dynamically stable structure which reduces the adverse effects of TEP. Leveraging these insights, we engineer a TEP-modified carbonate electrolyte with standard Li salt concentration (1 M) boasting both nonflammability and high ionic conductivity, enabling the Gr anode to achieve ∼100% capacity retention after 150 cycles. Additionally, this formulation significantly minimizes fire and explosion risks in 4 A h Gr||LiNi0.9Co0.05Mn0.05O2 pouch cells during mechanical stress, demonstrating profound implications for safer energy storage in LIBs.