Multidentate ether-induced reconfiguration of solvation structure in non-flammable phosphate electrolytes for wide-temperature application in lithium-ion batteries

Conventional carbonate electrolytes fail to meet the requirements for lithium-ion batteries (LIBs) with wide temperature range and high safety. Diethyl ethylphosphonate (DEEP) has excellent flame retardancy and a wide temperature range (-83 to 198°C), which holds promise for developing a non-flammable electrolyte for wide-temperature application in LIBs. However, its limited compatibility with graphite electrodes and slow ionic transport capability must be addressed for effective application. Herein, we introduce diethylene glycol dimethyl ether (DEGDME) to reconfigure the solvation structure of DEEP-based electrolyte and further enhance its ion transport capacity. The film-forming additives enable the electrolyte to preserve 98% capacity retention after 150 cycles for Li||Graphite cells The non-flammable DEEP-based electrolytes modified with DEGDME enable improved low-temperature performance with achieving 71% 50th-cycle retention of Graphite||LiFePO ₄ cells at -20°C. This work introduces a new strategy for designing non-flammable phosphate electrolytes, enabling the reliable and safe application of LIBs across a wide temperature range.