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

Chelating solvent-mediated ion-solvent coordinated structure is designed to modulate Li⁺-phosphates interaction, affording a high-efficiency pseduo-structrural diffusion, similar to high concentration electrolytes (HCEs) (>3 mol L⁻¹) and diluted DHCEs (>2 mol L⁻¹), yet in standard 1 mol L⁻¹ concentration with high ionic conductivity. The 25 Ah graphite|LiFePO₄ cells achieve stable operation at 2C rate with 71.0% capacity retention after 600 cycles.

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.