Research progress on lithium based Water-in-salt electrolytes

Compared with commercial organic based lithium (Li) ion batteries, aqueous lithium-ion batteries (ALIBs) present high safety, low cost and environment-friendly. However, due to the limitation of the electrochemical window of aqueous solution (1.23 V), it is excluded the most of electrochemical couples with the output voltage above 1.5 V. The invention of the Water-in-salt (WIS) electrolyte firstly expand stable electrochemical window of the aqueous electrolyte above 3.0 V which conceives of a series of high voltage ALIBs. The review mainly summarized research progress on Water-in-salt electrolyte and its relative following works, including the derivative electrolytes such as Water-in-bisalt electrolyte and its expanding applications on Li ion batteries, lithium-sulfur batteries and hybrid-ion batteries, and meanwhile introduces the fundamental investigation on the solid electrolyte interphase (SEI) formation mechanism and Li ion transport mechanism in WIS electrolytes.