High-voltage and high-safety lithium-ion batteries enabled by nonflammable electrolyte with enhanced Li⁺ desolvation behavior.

Abstract

Enhancing high-capacity silicon-graphite negative electrodes and high-voltage positive electrodes is crucial for improving specific energy of lithium-ion batteries. However, challenges like large volume change in silicon-graphite electrode and electrolyte decomposition at high voltage compromise electrochemical stability. Furthermore, sluggish Li⁺ exchange between electrolytes and electrodes severely hinders electrochemical kinetics. Herein, we design an anion-rich electrolyte with high oxidation resistance and rapid desolvation behavior, which enabling the formation of effective interphases for improving electrochemical performance. The optimized electrolyte allows silicon-graphite electrode to achieve 1838.9 mAh g^-1 capacity at 0.1 C with a long-term electrochemical stability, while a lithium-rich layered oxide positive electrode maintains 72.3% retention after 600 cycles at 1 C. The designed electrolyte with nonflammability also enhances safety in pouch cells after nail penetration. This design significantly improves cycling stability in high-specific-energy batteries, reaching specific energy of 278 Wh kg^-1 for graphite | |lithium-rich layered oxide and 355 Wh kg^-1 for silicon-graphite | |Ni-rich layer oxide pouch cells, calculated based on all cell components (positive electrode, negative electrode, separator and electrolyte). The design of the high-voltage electrolyte introduces a feasible approach to formulate a suitable solvation structure for high-specific-energy batteries.