Synergistic Structural and Interfacial Engineering of 3D Porous Micro-Electrodes for High-Performance Zn-Ion Micro-Batteries

Planar micro-batteries are promising power sources for emerging miniaturized electronics; however, their development is limited by insufficient active material loading and poor cycling durability within confined geometries. To address these challenges, we design three-dimensional (3D) porous gold (Au) interdigitated electrodes (IDEs) as multifunctional current collectors. The porous Au framework enables efficient integration of zinc anodes and nanowire polyaniline (PANI) cathodes, while a conformal PEDOT overlayer on the cathode stabilizes electrode-electrolyte interfaces and enhances long-term cycling. This hierarchical and surface-engineered electrode design achieves outstanding electrochemical performance, delivering a ~ 795% increase in areal capacity at a high areal current of 1000 µA cm⁻² compared to materials deposited on planar Au IDEs. Long-term cycling further demonstrates excellent durability, with ~ 84% capacity retention after 300 cycles, significantly higher than the ~ 68.65% observed for without conformal PEDOT. Ragone plot analysis highlights the superior energy-power balance of the optimized micro-batteries, achieving a peak areal energy of 17 µWh cm⁻² at a peak areal power of 4361 µW cm⁻², surpassing most reported micro-batteries and micro-supercapacitors. These findings establish the synergistic integration of 3D current collectors and PEDOT-engineered polymer cathodes as a scalable pathway toward high-performance Zn-ion micro-batteries, providing a reliable and versatile energy solution for powering next-generation miniaturized systems.