Fire-Resistant Carboxylate-Based Electrolyte for Safe and Wide-Temperature Lithium-Ion Batteries

Abstract

The combustion accident and narrow temperature range of rechargeable lithium-ion batteries (LIBs) limit its further expansion. Non-flammable solvents with a wide liquid range hold the key to safer LIBs with a wide temperature adaptability. Herein, a carboxylate-based weak interaction electrolyte is achieved by molecular design, which consists of EDFA (ethyl difluoroacetate), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropylether, and fluoroethylene carbonate. The inherent non-flammable and wide liquid-rang features of the electrolyte ensure the safety as well as the wide operating temperature of a battery. The high affinity between FSI⁻ anions and counter Li⁺ guarantees a stable and inorganic-components-dominated electrolyte/electrode interphase with rapid Li⁺ de-solvation kinetics, leading to perfect compatibility with graphite and avoiding side reactions between lithiated graphite and electrolyte. The rationally designed EDFA-based electrolyte enables the thick graphite (4.4 mAh cm⁻²) || LiNi_0.8Co_0.1Mn_0.1O₂ (4.0 mAh cm⁻²) cells to operate efficiently in a wide temperature range from −30 to 45 °C. The proposed EDFA-based electrolyte enables the commercial 1.0 Ah graphite || NCA (LiNi_0.8Co_0.15Al_0.05O₂, >3.2 mAh cm⁻²) pouch cells stably cycle for >1100 cycles (>85% capacity retention) at 0.3C and >800 cycles at 1.0C (>92% capacity retention), while also endows the graphite/SiO_x and Li anode-based batteries with high energy density, long lifespan and high safety.