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

Abstract

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.