On-Chip 3D Zn/NiOOH Helical Electrodes for High-Energy-Density Microbattery

Explosive progress in wireless and functional mobile electronics calls for miniaturized energy-storage units to push forward energy-autonomous and self-sustainable intelligent microsystems. Emerging three-dimensional (3D) microstructured electrodes for energy-storage devices have drawn great attention due to their attractive stereoscopic architectures to increase the areal loading of active materials. Here, we report a strategy for fabricating a 3D helical electrode for a zinc microbattery (Zn MB) by combining a “top-down” lithography technique and a “bottom-up” electrochemical depositing process. Thanks to the available stereoscopic space, the achieved 3D helical electrode shows a high surface area, outstanding electrolyte permeation, and stress adaptive capability. Based on the structural advantages of a 3D helical electrode, high-performance rechargeable Zn MB has been achieved by depositing Zn and NiOOH as anode and cathode materials, respectively. The Zn microbattery demonstrates a specific areal capacity up to 0.325 mAh·cm–2 corresponding to a high energy density of 0.55 mWh·cm–2. It also exhibits remarkable rate capability (0.272 mAh·cm–2 at 100 mA·cm–2) and excellent cycling stability (85% retention after 1000 cycles). The outstanding electrochemical performance indicates that the 3D Zn MB can work as a promising power source for advanced electronic devices. Paired micro-/nanofabrication process for battery electrodes is also of great significance in gearing toward carbon-neutral.