Advanced 3D Micro‐Electrodes for On‐Chip Zinc‐Ion Micro‐Batteries

Abstract The development of high‐performance planar micro‐batteries featuring safer, cost‐effective systems is crucial for powering smart devices such as medical implants, micro‐robots, micro‐sensors, and the Internet of Things (IoT). However, current on‐chip micro‐batteries suffer from limited energy density within constrained device footprints due to challenges in effectively loading high‐capacity active materials onto micro‐electrodes. Innovative designs for advanced micro‐electrodes are needed for on‐chip micro‐batteries. This work introduces advanced, highly porous 3D gold (Au) scaffold‐based interdigitated electrodes (IDEs) as current collectors, which enable effective loading of active materials (Zn and polyaniline) without compromising overall conductivity and significantly increase active mass loading. These 3D Au scaffold‐based micro‐batteries (3D P‐ZIMB) offer substantially higher energy storage performance (≈135% enhancement) compared to conventional micro‐batteries (C‐ZIMB) when materials loaded onto flat Au IDEs. Furthermore, the 3D P‐ZIMB demonstrates higher areal capacities (≈35 µAh cm⁻²) and areal energy (≈31.05 µWh cm⁻²) than most high‐performance on‐chip micro‐batteries, and it delivers a much higher areal power (≈3584.35 µW cm⁻²) than high‐performance on‐chip micro‐supercapacitors. In‐depth postmortem investigations reveal that the 3D P‐ZIMB avoids issues like material peeling, sluggish electrolyte ion diffusion, and dendrite formation on the anode, while maintaining identical material morphologies and structural characteristics. Therefore, this study presents a smart strategy to enhance the electrochemical performance of planar micro‐batteries and advance the field of on‐chip micro‐battery research.