A Photolithographable Electrolyte for Deeply Rechargeable Zn Microbatteries in On‐Chip Devices

Zn batteries show promise for microscale applications due to their compatibility with air fabrication but face challenges like dendrite growth and chemical corrosion, especially at the microscale. Despite previous attempts in electrolyte engineering, achieving successful patterning of electrolyte microscale devices has remained challenging. Here, successful patterning using photolithography is enabled by incorporating caffeine into a UV-crosslinked polyacrylamide hydrogel electrolyte. Caffeine passivates the Zn anode, preventing chemical corrosion, while its coordination with Zn