3D Porous Metal-Scaffold Interdigitated Micro-Electrodes for High-Performance On-Chip Energy Storage Systems

The development of on-chip energy storage systems is essential for the next generation of System-on-Chip (SoC) technologies, particularly in powering micro-scale devices such as medical implants, micro-robots, and micro-sensors. Enhancing charge storage performance within a limited device footprint remains a key challenge, necessitating advancements in electrode design to improve energy storage capabilities. In this work, porous 3D copper (Cu) scaffold-based interdigitated electrodes (IDEs) are introduced as current collectors, where the dynamic hydrogen bubble templating (DHBT) method is employed to fabricate porous Cu scaffold IDEs, resulting in a structured porous network with increasing porosity at the top surface. This design greatly enhances the efficient loading of electrode materials of polyaniline (PANI) cathode and zinc (Zn) anode, thereby improving charge storage performance in Zn-ion micro-batteries (3D ZIMBs) and facilitating the deposition of activated carbon (AC) on 3D porous Cu for 3D micro-supercapacitors (3D MSCs). Our results demonstrate a substantial improvement in charge storage for 3D ZIMBs, achieving 32.46 µAh cm⁻² compared to ZIMBs (PANI and Zn deposited on plane Au IDEs) with 16.99 µAh cm⁻² at 100 µA cm⁻². Similarly, the 3D MSCs exhibit an areal capacitance of 22.81 mF cm⁻² at 0.1 mA cm⁻², outperforming MSCs (AC deposited on plane Au IDEs) with 4.52 mF cm⁻². Furthermore, the 3D ZIMBs and 3D MSCs achieve impressive areal energies of 29.62 and 4.04 µWh cm⁻², respectively, outperforming most reported high-performance on-chip energy storage systems. Therefore, this study presents an innovative strategy to enhance the electrochemical performance of planar energy storage systems and contribute to the advancement of on-chip energy storage research.