Electron-Donating or -Withdrawing Groups of Carbonate Solvent on Lithium-Ion (De)intercalation Chemistry
Jia Wang, Pushpendra Kumar, Zheng Ma, Honghong Liang, Fei Zhao, Hongliang Xie, Yuqi Wang, Tao Cai, Z. Cao, Luigi Cavallo, Qian Li, Jun Ming
Abstract
Cyclic carbonate solvents have been extensively utilized as cosolvents and/or additives in formulating electrolytes for lithium-ion batteries. However, their application often relies on empirical knowledge, lacking a universally applicable perspective to elucidate how different functional groups in cyclic carbonates affect battery performance. Herein, by focusing on the substituted functional group at the α-H in the ethylene carbonate (EC) solvent, it is discovered that solvents containing electron-withdrawing groups (e.g., −F) enable reversible Li + (de)intercalation in graphite electrodes, while those with electron-donating groups (e.g., −CH 3, −CH 2 CH 3 ) may lead to Li + -solvent cointercalation. Furthermore, solvents with electron-withdrawing groups can help the electron-donating groups achieve Li + (de)intercalation, whereas the reverse is not feasible. These phenomena are elucidated through intermolecular interactions, characterized by 2D 1 H– 19 F heteronuclear Overhauser enhancement spectroscopy, revealing interactions between electron-withdrawing and -donating groups in the electrolyte solvation structure. This study offers insights into the roles of electron-donating or -withdrawing groups in electrolyte formulations.