CO 2 -sourced anti-freezing hydrogel electrolyte for sustainable Zn-ion batteries

Low-temperature operation of hydrogel electrolyte is limited by their poor ionic conductivity. Meanwhile, greener and sustainable batteries are in demand from an environmentally friendly perspective. Herein, we report an anti-freezing hydrogel electrolyte based on CO 2 -derived cyclic carbonate crosslinked with potassium polyacrylate/polyacrylamide for sustainable Zn-ion battery. Such a CO 2 -sourced hydrogel electrolyte with wealthy polar functional groups enables its high flexibility (twisting, compressing, and stretching) and good specific capacity (80.4% retention of the counterpart at 25 °C) at −20 °C. Furthermore, the spent hydrogel electrolyte can subsequently be degraded on demand in alkaline conditions. This work provides an effective strategy to integrate CO 2 -sourced anti-freezing and degradable hydrogel electrolytes for sustainable energy storage devices.