One-Step Synthesis of Co3O4/Graphene Aerogels and Their All-Solid-State Asymmetric Supercapacitor

A facile one-step hydrothermal strategy has been developed to prepare 3D porous Co3O4/graphene aerogel (Co3O4/GA). Due to the combination of a highly interconnected 3D network of GA and porous Co3O4 nanospheres, the resulting Co3O4/GA electrode exhibits exceptional electrical conductivity and pseudocapacitance, making it an excellent material for energy-storage devices. The Co3O4/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 Co3O4 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 Co3O4/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 Co3O4/GA could be a potential candidate in the field of supercapacitors.