3D printed dual network Cross-Linked hydrogel electrolytes for high area capacity flexible zinc ion Micro-Batteries

Hydrogel electrolytes have wide applications in flexible zinc ion micro-batteries (FZIMBs) due to their excellent mechanical flexibility, biocompatibility, and ionic conductivity. However, traditional templating methods are limited to fabricating two-dimensional and simple three-dimensional structures, making them insufficient for preparing complex structures in FZIMBs. Here, we report a printable hydrogel electrolyte ink with excellent rheological properties. By utilizing 3D printing technology, we achieve the preparation of a custom-shaped, double-network crosslinked polyacrylamide-hydroxypropyl methylcellulose hydrogel electrolyte (PHHE). The PHHE exhibits high ionic conductivity (31.72 mS cm−1), good cycling stability, and mechanical flexibility. Furthermore, we constructed FZIMBs with high areal capacities (6.45 mAh cm−2 at 0.5 mA cm−2) and good mechanical flexibility by leveraging PHHE and 3D printing technology. Integrating FZIMBs with a pressure sensing component, we establish a sensing interaction system, demonstrating practical applications of flexible wearable devices. This work presents a novel method for the preparation of customized hydrogel electrolytes and highlights the significant potential of FZIMBs in practical applications.