Synergic Coordination Effect in Nonflammable Deep Eutectic Electrolyte for High‐Performance Sodium‐Ion Batteries
Ao Xu, Zhao Li, Jingyuan Yu, Wei Deng, Jingni Li, Hong Zhang, Hantao Xu, Lin Xu
Abstract
Abstract Deep eutectic electrolytes (DEEs) are emerging as a highly promising class of next‐generation electrolytes, poised to revolutionize the performance of safe sodium‐ion batteries (SIBs). Nevertheless, a significant challenge hindering the progress of SIBs is the scarcity of suitable DEEs capable of harmonizing electrolyte conductivity, interfacial compatibility, and safety. In this study, we have engineered a DEE leveraging the synergistic interplay between Na‐bonds and hydrogen bonds, achieved through the integration of N ‐methylacetamide (NMA) and sodium‐difluoro(oxalato)borate (NaDFOB). The findings reveal that the distinctive interaction between the polar C═O group in NMA and Na + ions, coupled with hydrogen bonding with DFOB − anions, facilitates the formation of the DEE. The designed DEE demonstrates exceptional ionic conductivity (4.03 mS cm −1 at 25 °C), a high oxidation voltage (4.63 V versus Na + /Na), and nonflammability. The unique solvation structure markedly enhances the compatibility of the electrode–electrolyte interface, with the NVP||Na cell exhibiting outstanding cycling performance (86.8% retention after 7000 cycles at 5 C) and superior rate capability. Moreover, the DEEs exhibit robust performance at elevated temperatures (94.3% retention after 120 cycles with NVP||Na cell), and the full cell demonstrates significant enhancements in both cycle stability (90.7% retention after 300 cycles) and rate performance. The incorporation of amide‐based eutectic electrolytes into SIBs infuses fresh vitality into electrolyte design, propelling the advancement of high‐performance SIBs.