Exceptional Battery‐level Safety of High Energy Density Lithium‐Ion Batteries through Non‐Flammable and Low‐Exothermic Localize High Concentration Electrolytes

The poor safety performance of high energy density lithium ion batteries (LIBs) is drawing increasing public concern. To enhance the safety performance on the battery level, it is indispensable to design safe electrolytes that are both non‐flammable and low exothermic under abusive conditions. By rational design, a safe localize high concentration electrolyte (LHCE) with non‐flammability and extremely low exothermicity is formulated. Compared with conventional LiPF6‐organocabonate electrolytes and previous LHCEs, the heat generated by the reaction between the safe LHCE and fully charged electrodes under abusive conditions is significantly reduced. Because of the non‐flammability and low‐exothermicity of the safe LHCE, high energy density LIB (1800 mAh, fully charged to 4.3V) with the safe LHCE successfully passes the nail penetration test. Because of the excellent interphasial properties of the safe LHCE, the cycle life and the rate capability of high energy density LIBs are significantly improved when the safe LHCE is adopted. This work sheds light on the design principles of electrolytes for achieving battery‐level safety.