A Superconcentrated Water-in-Salt Hydrogel Electrolyte for High-Voltage Aqueous Potassium-Ion Batteries

We report a high-voltage aqueous full potassium-ion battery (AFKIB) with a superconcentrated water-in-salt hydrogel electrolyte (WISHE). This WISHE exhibits an expanded electrochemical stability window (ESW) of 3.0 V as well as a high ionic conductivity of 4.34 mS cm(-1). The hydrogen bonds between the polymer network and the water phase help to further widen the ESW over a liquid-type water-in-salt electrolyte, and prevent liquid leakage. The assembled AFKIB exhibits a considerable capacity of 135 mA h g(-1) and a superior stability after 3000 cycles. This work provides a meaningful way of designing high-voltage aqueous energy storage devices.

Automated summary

In this study, a high-voltage aqueous full potassium-ion battery (AFKIB) with superconcentrated water-in-salt hydrogel electrolyte (WISHE) was developed. The WISHE demonstrated an expanded electrochemical stability window (ESW) and high ionic conductivity, contributing to the superior performance and stability of the assembled AFKIB. This work offers a meaningful approach for designing high-voltage aqueous energy storage devices.