A Conformal Active-Material Loading Strategy for Designing High-Performance Planar Microsupercapacitors

Microsupercapacitors (MSCs) show promise for use in wearable electronics for biomedical, consumer, and military applications. However, the development of innovative engineering technologies that enable high-capacity loading of active materials on the MSCs is still challenging. In this work, we report a conformal active-material loading strategy for developing high-performance planar MSCs based on stereoscopic carbon electrodes produced via direct laser writing (DLW). Oxidized laser-induced graphene (LIG-O) was prepared by combining laser-induced pyrolysis of polyimide (PI) and oxygen plasma-induced oxidation. The resultant LIG-O electrodes showed well-defined micropatterns, protuberant stereoscopic structures, high porosities, and superhydrophilicity. The combined effects enabled high-capacity loading of active materials (e.g., NiFe layered double hydroxide) on the stereoscopic carbon electrodes in a conformal manner, which contributed to a 10-fold improvement in the areal capacitances of the planar MSCs. In addition, the resultant flexible planar MSCs served as energy storage devices to power a flexible ink display system. This work will open new avenues for developing high-performance planar MSCs.