Battery safety has an ever-increasing significance and is required for consumer's safety. The high flammability of traditional organic liquid electrolyte, which consists of ethylene carbonate and highly flammable linear carbonate, is one of the major reasons for thermal runaway and battery fire events. Replacement of flammable liquid electrolyte with non-incendive one is urgently needed for safe lithium-ion batteries. A fluorinated linear sulfate paired with 1 m LiPF6 was developed and evaluated as a solvent of non-incendive liquid electrolyte for a use in high-voltage (4.4 V) and high-temperature (45 °C) LiNi0.82 Mn0.07 Co0.11 O2 (NCM811) chemistry-based lithium-ion batteries. Non-incendive liquid electrolyte containing sulfate with two trifluoroethyl groups exhibited superior anodic and thermal stability and promoted cathode-electrolyte and anode-electrolyte interfacial stability, compared to flammable traditional electrolyte. Non-incendive electrolyte showed markedly improved 300 cycle performance of an industrial graphite‖NCM811 lithium-ion pouch cell with a nominal capacity of 730 mAh under harsh conditions, and high safety of 10 V overcharge abuse tolerance, from which safe and high-performing high-energy lithium-ion batteries and battery-powered electric vehicles and energy storage system are anticipated.
Keywords: battery safety; electrolytes; energy storage; high-voltage; lithium-ion batteries.
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