Recent advances in water in salt electrolytes for aqueous rechargeable monovalent-ion (Li+, Na+, K+) batteries

Aqueous rechargeable batteries have attracted enormous attention owning to their intrinsic characteristics of non-flammability, low cost, and the superior ionic conductivity of the aqueous electrolyte. However, the narrow electrochemical stability window (1.23 V), imposed by hydrogen and oxygen evolution, constrains the overall energy density of batteries. The revolutionary water-in-salt electrolytes considerably expand the electrochemical stability window to 3 or even 4 volts, giving rise to a new series of high-voltage aqueous metal-ion chemistries. Herein, the recent advances in water-in-salt electrolytes for aqueous monovalent-ion (Li+, Na+, K+) rechargeable batteries have been systematically reviewed. Meanwhile, the corresponding reaction mechanisms, electrochemical performances and the existing challenges and opportunities are also highlighted.(C) 2021 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

This review summarizes the recent advances in water-in-salt electrolytes for aqueous monovalent-ion rechargeable batteries and discusses the corresponding reaction mechanisms, electrochemical performances, as well as the existing challenges and opportunities.