High‐Performance Flexible Solid‐State Asymmetric Supercapacitors based on Ordered Mesoporous Cobalt Oxide

Abstract Asymmetric supercapacitors (ASCs) have attracted growing interest and attention in the field of supercapacitors owing to their high energy density and power density. In this work, ordered mesoporous Co 3 O 4 samples with different pore sizes (ca. 20 nm and ca. 70 nm) are prepared via a hard template method. Flexible solid‐state ASC devices based on mesoporous Co 3 O 4 with pore size of 20 nm and activated carbon possesses a specific capacitance of 215 mF cm −2 (at 1.5 mA cm −2 ) and show excellent cycling performance. Electrochemical tests reveal that the mesoporous material with a larger specific surface area, that is, a smaller primary particle size, is more suitable for solid‐state ASC device. The results provide a potential electrode material for ACSs.