Dynamic Cross-Linking Network Construction of Flexible Hydrogel Electrolyte Enabling Dendrite-Free Zinc Anode

Abstract

Aqueous zinc-ion batteries (AZIBs) are highly promising for flexible electronics and advanced energy storage due to their eco-efficiency, safety, and low cost. However, their practical application is limited by severe zinc dendrite growth, side reactions, and mechanical instability associated with conventional electrolytes. Herein, a novel chondroitin sulfate-functionalized polyacrylamide (PAM-CS) hydrogel electrolyte to address these challenges is presented. The PAM-CS hydrogel integrates multiple functional groups, including hydroxyl (─OH), strongly electronegative sulfonic acid (─SO₃⁻), and carboxylic acid (─COO⁻) groups, which form hydrogen bonds with free water molecules to reduce their activity and suppress side reactions. Furthermore, the strongly electronegative groups (─SO₃⁻ and ─COO⁻) construct dynamic coordination networks by strong electrostatic interactions, which enable fast Zn²⁺ migration and promote uniform Zn²⁺ deposition. As a result, the Zn||PAM-CS||Zn symmetric cell demonstrates stable cycling for over 1200 h at 1 mA cm⁻²/1 mAh cm⁻², while the Zn||PAM-CS||NH₄V₄O₁₀ full cell exhibits an outstanding rate performance and specific capacity of 87 mAh g⁻¹ at a high current density of 5 A g⁻¹. Additionally, a flexible pouch battery using PAM-CS exhibits robust performance under mechanical stress, including bending, puncture, and cutting, showcasing its potential for wearable electronics.