A Competitive Ion-Dipole Interaction-Regulated Nonflammable Electrolyte Enables High-Energy-Density Li-Ion Batteries with Li-Rich Oxide Cathodes.

Developing nonflammable electrolytes with high-voltage resistance and high electrode compatibility is crucial for high-energy-density and highly safe lithium-ion batteries (LIBs). However, the relationship of component interactions (i.e., anion-solvent and solvent-solvent) and electrochemical performance is not fully understood. Herein, we present a competitive ion-dipole interaction between anions and fluorinated solvents to elucidate the solvation structure regulation mechanism for stabilizing the high-voltage performance of Li-rich layered oxide (LRLO) cathodes with an anionic redox reaction. We demonstrate a weakly solvating electrolyte with competitive ion-dipole interaction to avoid electrolyte decomposition caused by nucleophilic attack from oxygen species in the LRLO cathodes and scavenge active oxygen by anions to form an inorganic-rich interface. As a result, the electrolytes mentioned above with nonflammability enable high cycling stability for LRLO. Moreover, the silicon-graphite composite (Si-C)//LRLO pouch cell equipped with the optimal electrolyte can stably operate at 4.6 V and achieve a high energy density of 323.1 Wh kg-1. This research provides new insights into solvation structure regulation for improving the electrochemical performance of high-voltage LIBs.