Enabling high-energy-density aqueous batteries with bond-anchored electrolytes

Conventional aqueous electrolytes suffer from a narrow voltage window due to water decomposition. Highly concentrated electrolytes expand the voltage window; however, they are limited by high cost and potential toxicity. Here, we develop a hydrogen bond-anchored electrolyte by introducing sulfolane as hydrogen bond acceptor to limit water activity. The designed electrolyte expands the voltage window to 3.4 V (1.3-4.7 V versus Li+/Li) and forms a hierarchical anode-electrolyte interphase to suppress the hydrogen evolution reaction. An aqueous Li4Ti5O12/LiMn2O4 full cell achieved 141 W h kg(-1) for 300 cycles at 1 C and 125 W h kg(-1) for 1,000 cycles at 5 C with a high Coulombic efficiency of 99.5%- 99.9%. On-line electrochemical mass spectroscopy shows negligible hydrogen/oxygen gas evolution upon cycling, further confirming the stability of the designed electrolyte. This work demonstrates a rational and effective approach to suppress the hydrogen evolution reaction and achieve stable high-voltage aqueous batteries.

Automated summary

In this study, a hydrogen bond-anchored electrolyte is developed to limit water activity and expand the voltage window. The designed electrolyte suppresses the hydrogen evolution reaction and achieves stable performance in high-voltage aqueous batteries.