Anti-Freezing Hydrogel Electrolyte with Regulated Hydrogen Bond Network Enables High-Rate and Long Cycling Zinc Batteries

Abstract

Zinc-based batteries, utilizing hydrogel electrolytes, present significant promise as power sources for next-generation flexible devices due to their stretchable nature and enhanced safety features. Nonetheless, the current hydrogel electrolytes require improvements in terms of cycling stability and rate capability. In this study, 1,2-propylene glycol is added as co-solvent to polyacrylamide hydrogel electrolytes. The co-solvent effectively modulates the internal hydrogen bond network of the hydrogel through hydroxyl and terminal methyl groups, inhibits the activity of water while preventing the solvent from forming “hand-in-hand” long-chain molecular structure, and enhances the stability of the electrode/electrolyte interface. Consequently, the symmetrical battery assembled with PAM-1,2-PG exceeded 490 h at 100 mA cm-2 and 50 mA h cm-2 (DOD of 86%). The change of hydrogen bond network endows the battery with remarkable low-temperature performance, which is more than 3780 h under -30 °C at 1 mA cm-2. Furthermore, the resulting aqueous zinc-based devices showcase high capacity and outstanding cycling durability in a wide temperature range. This work provides valuable insights into the development of high-performance hydrogel electrolytes, paving the way for dendrite-free, fast-charging, and environmentally adaptable Zn-based energy storage systems.