One‐Step Synthesis of Co 3 O 4 /Graphene Aerogels and Their All‐Solid‐State Asymmetric Supercapacitor

A facile one‐step hydrothermal strategy has been developed to prepare 3D porous Co 3 O 4 /graphene aerogel (Co 3 O 4 /GA). Due to the combination of a highly interconnected 3D network of GA and porous Co 3 O 4 nanospheres, the resulting Co 3 O 4 /GA electrode exhibits exceptional electrical conductivity and pseudocapacitance, making it an excellent material for energy‐storage devices. The Co 3 O 4 /GA composites possess a high specific surface area of 127 m 2 g –1 and a broad pore‐size distribution of 1–110 nm. The presence of porous Co 3 O 4 is found to be remarkably effective in enhancing the specific capacitance of the composite aerogel, up to 1512.7 F g –1 at 1 A g –1 . Furthermore, the combination of the two aerogel electrodes with a LiOH/PVA‐gel electrolyte endows our all‐solid‐state asymmetric supercapacitor (SASC) of Co 3 O 4 /GA//GA with a stable cycling performance in the high‐voltage region of 0–1.6 V (capacitance retention of 81.5 % after 5000 continuous charge/discharge cycles), and superior electrochemical performance, with an energy density of 68.1 W h kg –1 at a power density of 982.9 W kg –1 , which is even higher than the maximum energy density of 58.7 W h kg –1 at a power density of 1209.4 W kg –1 of this ASC in a liquid‐state electrolyte. These results indicate that Co 3 O 4 /GA could be a potential candidate in the field of supercapacitors.