Nonflammable Liquid Electrolytes for Safe Lithium Batteries

Lithium‐based batteries (lithium‐ion batteries, lithium‐metal batteries, and lithium–sulfur batteries, etc.) have become one of the most irreplaceable energy‐storage devices and shown huge application potential. However, the traditional liquid electrolytes used in lithium‐based batteries are flammable and exhibit poor electrochemical stability, which will significantly limit the further development of high energy density and high safety lithium‐based batteries. Thus, it is crucial to develop nonflammable electrolytes. In this work, the reasons why traditional liquid electrolyte is unsafe and the recent progress of nonflammable liquid electrolytes including flame‐retardant‐based electrolytes, highly concentrated electrolytes, localized high concentrated electrolytes, and ionic liquids–based electrolytes are summarized. The challenges and future perspectives toward how to decrease the fire hazard of lithium‐based batteries through liquid electrolyte design are also put forward.