An Insight into Synthesis of the Antifreeze Alkaline Hydrogel Electrolyte: Fine‐Tuning Chemistries for Efficient Ion Transport

Abstract

Herein, the chemical compatibility of the hydrogel electrolyte in highly alkaline pH was evaluated. Through simple experiments, we demonstrated that the frequently used polymer compound, acrylamide, is not stable at a high pH. The addition of glycerol as a cryoprotectant in highly alkaline hydrogels was also problematic due to the possible base‐initiated decomposition of glycerol to polyglycerols. Hence, a quick and simple one‐pot synthesis of highly alkaline potassium poly(acrylate) hydrogel with 1 vol % glycerol was proposed. The ionic conductivities of the hydrogel are 46.48 mS/cm and 8.67 mS/cm at 22 and −23 °C, respectively. One important benefit from the addition of the cryoprotectant is that the hydrogel sustained its mechanical features at temperatures as low as −80 °C. We also reported here for the first time the diffusion coefficients (D at ∼10−8 cm2/s), ionic mobilities (μ at ∼10−7 cm2/Vs), and ion density (n at ∼10−7 cm−3) of the hydrogel electrolyte used in flexible alkaline batteries.