Li-N Interaction Induced Deep Eutectic Gel Polymer Electrolyte for High Performance Lithium-Metal Batteries.

As emerging eutectic mixtures, deep eutectic electrolytes (DEEs) show unique properties for Li-metal batteries (LMBs). However, the limited choice and inferior electrode compatibility hinder their further development in LMBs. Herein, we report a new 1,2-dimethylimidazole (DMIm)-based deep eutectic gel polymer electrolyte induced by Li-N interaction. We demonstrate that incorporating electron-withdrawing polyvinylidene difluoride (PVDF) polymer into the DMIm-based DEE changes the coordination environment of Li ions, leading to a high transference number of Li ions (0.65) and superior interface stability between the electrolyte and Li anode. The deep eutectic gel polymer electrolyte exhibits excellent non-flammability, high ionic conductivity (1.67 mS cm at 30 °C), and high oxidation voltage (up to 4.35 V vs. Li/Li ). The Li||LFP cell based on the newly developed deep eutectic gel polymer electrolyte can achieve superior long-term cycling stability at a wide range of rates.