Chelating Solvent Mediated Solvation Structure Enables High-Rate Operation of Ah-Level Li-Ion Batteries in Nonflammable Phosphate Electrolyte

Abstract

Highly flammable carbonate electrolytes induce significant safety risk for lithium-ion batteries (LIBs), raising concerns about their suitability for large-scale applications. In contrast, non-flammable phosphate electrolytes offer a potential solution, yet the untamed strong interaction of Li⁺-phosphates and inefficient Li⁺ diffusion result in sluggish reaction kinetics, which restricts the operation of Ah-level LIBs to rates below 0.2C. Herein, a chelating solvent-mediated ion-solvent coordinated structure is designed to modulate Li⁺-phosphates interaction. This innovative approach enables a high-efficiency pseduo-structrural diffusion, similar to that observed in high concentration electrolytes, while maintaining a standard concentration of 1 mol L⁻¹ and achieving high Li⁺ conductivity. The operating rate of Ah-level graphite|LiFePO₄ cells is increased from 0.2C to 2C, with 1 Ah and 25 Ah cells retaining 73.9% and 71.0% capacity after 1000 and 600 cycles, respectively. Additionally, the maximum temperature of 25 Ah cells during nail penetration is significantly reduced from 338.9 to 200 °C. This strategy provides promising tuition for developing advanced electrolytes.