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Recharging battery‐powered electric vehicles (EVs) in a similar timeframe as those used for refueling gas‐powered internal combustion vehicles is highly desirable for rapid penetration of the EV market. It is well known that the electrolyte in a battery plays a critical role in fast‐charging capability of the battery because it determines the rate of ion transport together with its derived electrode/electrolyte interphases on both cathode and anode of the battery. In this study, the effects of contents of salt, coordinating solvent, and noncoordinating diluent on salt dissociation degree and electrolyte ionic conductivity are investigated, and a controlled solvation structure electrolyte is developed to improve the lithium ion mobility and conductivity in the electrolyte and to enhance the kinetics and stability of the electrode/electrolyte interphases in the battery. This electrolyte enables fast‐charging capability of high energy density lithium‐ion batteries (LIBs) at up to 5 C rate (12‐min charging), which significantly outperforms the state‐of‐the‐art electrolyte. The controlled solvation structure sheds light on the future electrolyte design for fast‐charging LIBs. [ABSTRACT FROM AUTHOR]

It has been widely assumed that the flammability of the liquid electrolyte is one of the most influential factors that determine the safety of lithium‐ion batteries (LIBs). Following this consideration, a completely nonflammable electrolyte is designed and adopted for graphite||LiFePO4 (Gr||LFP) batteries. Contrary to the conventional understanding, the completely nonflammable electrolyte with phosphorus‐containing solvents exhibits inferior safety performance in commercial Gr||LFP batteries, in comparison to the flammable conventional LiPF6‐organocarbonate electrolyte. Mechanistic studies identify the exothermic reactions between the electrolyte (especially the salt LiFSI) and the charged electrodes as the "culprit" behind this counterintuitive phenomenon. The discovery emphasizes the importance of reducing the electrolyte reactivity when designing safe electrolytes, as well as the necessity of evaluating safety performance of electrolytes on a battery level. [ABSTRACT FROM AUTHOR]