Recent status and future perspectives of ultracompact and customizable micro-supercapacitors

Ultracompact and customizable micro-supercapacitors (MSCs) are highly demanded for powering microscale electronics of 5G and Internet of Things technologies. So far, tremendous efforts have been concentrated on fabricating high-performance MSCs; however, compatible fabrication and monolithic integration of MSCs with microelectronic systems still remains a huge challenge taking into full consideration the factors such as electrode film fabrication, high-resolution microelectrode pattern, and electrolyte precise deposition. In this review, we summarize the recent advances of ultrasmall and integrated MSCs with tunable performance and customizable function, including key microfabrication technologies for patterning microelectrodes with superior resolution, precise deposition of customized electrolytes in an extremely small space, and feasible strategies for improving electrochemical performance by constructing thick microelectrodes and special electrode structure. Finally, the related challenges and key prospects of ultracompact and customizable MSCs, including compatible microfabrication methods for electrode materials and films, patterning microelectrodes, customizing shape-conformable electrolytes, performance optimization, and efficient integration with microelectronic systems, are put forward for further promoting their practical application.