On‐Chip Ni–Zn Microbattery Based on Hierarchical Ordered Porous Ni@Ni(OH)2 Microelectrode with Ultrafast Ion and Electron Transport Kinetics

Abstract On‐chip microbatteries have attracted growing attention due to their great feasibility for integration with miniaturized electronic devices. Nevertheless, it is difficult to get both high energy/power densities in microbatteries. An increase in the thickness of microelectrodes may help to boost the areal energy density of device, yet it often leads to terrible sacrifice in its power density due to the longer electron and ion diffusion distances. In this work, a quasi‐solid‐state on‐chip Ni–Zn microbattery is designed based on a hierarchical ordered porous (HOP) Ni@Ni(OH) 2 microelectrode, which is developed by an in situ anodizing strategy. The fabricated microelectrode can optimize ion and electron transport simultaneously due to its interconnected ordered macropore–mesopore network and high electron conductivity. As the thickness of microelectrode increases, the areal energy density of HOP Ni@Ni(OH) 2 microelectrode shows an ascending trend with negligible sacrifice in power density and rate performance. Impressively, this Ni–Zn microbattery achieves excellent energy/power densities (0.26 mW h cm −2 , 33.8 mW cm −2 ), outperforming most previous reported microenergy storage devices. This study may provide new direction in high‐performance and highly safe microenergy storage units for next‐generation highly integrated microelectronics.