Suppression of Zinc Dendrite Growth by Enhanced Polyacrylamide Gel Electrolytes in Zinc-Ion Battery

Aqueous zinc-ion batteries have become a promising energy storage battery due to high theoretical specific capacity, abundant zinc resources and low cost. However, zinc dendrite growth and hydrogen evolution reaction limit their application. This study aims to improve the cycling performance and stability of aqueous zinc-ion batteries by improving the gel electrolyte. Polyacrylamide (PAM) is selected as the base material of the gel electrolyte, which has good stability and safety, but the water retention capacity, Zn2+ migration number, and ionic conductivity of PAM are low, which affects the long-term stability of the battery. In response to these problems, we optimized PAM by chemical cross-linking method, and formed an enhanced PAM gel by adding disodium citrate dihydrate (SC). Experimental results show that the introduction of an appropriate amount of SC in the enhanced PAM gel electrolyte can significantly improve its electrochemical performance. The zinc-ion symmetric battery achieved a stable cycle of more than 2100 hours at a current density of 0.5 mA cm-2, which is mainly attributed to the inhibitory effect of the enhanced PAM gel on zinc dendrite growth and hydrogen evolution reaction. This study provides a new direction for the development and application of flexible zinc-ion batteries. The enhanced PAM/SC gel electrolyte was formed by adding disodium citrate dihydrate, which has a rich pore structure and that is conducive to rapid ion transport. The PAM/SC gel inhibits the vertical growth of Zn (100) crystal planes, when it was employed as electrolyte for zinc-ion symmetric battery, the battery operated continuously for 2100 h. image