Laser-Induced Graphitization on Hydrogel for Gel Electrolyte-Cathode Integrated Zinc–Air Batteries

Zinc–air batteries (ZABs) possess high energy density and utilize earth-abundant zinc, making them attractive candidates for next-generation sustainable energy storage devices. To meet the increasing demand for flexible power sources in wearable devices, flexible ZABs have been studied by integrating the cathode and gel electrolyte into a single structure. However, the conventional fabrication of such integrated structures often requires a complicated and multistep fabrication process, which increases manufacturing costs. In this study, a gel electrolyte-cathode integrated structure was fabricated in two steps. First, we fabricated graphitic carbon (GC) on the gel electrolyte by laser-induced graphitization of lignin-containing agarose hydrogel. Second, we added gold chloride solution dropwise onto GC to decorate GC with Au clusters. The performance of ZABs prepared with the structures decorated with Au clusters was improved, exhibiting higher open-circuit voltages and maximum power densities than those without Au cluster decoration. Furthermore, the Au clusters remained decorated on GC even after the drying–reswelling process, demonstrating that the prepared ZABs can function by reswelling even after drying. The new, simple method proposed in this study for fabricating a gel electrolyte-cathode integrated structure is expected to be an effective strategy for the practical application of flexible ZABs.