Self-Assembled 3D Graphene-Based Aerogel with Co3O4 Nanoparticles as High-Performance Asymmetric Supercapacitor Electrode

Using graphene oxide and a cobalt salt as precursor, a three-dimensional graphene aerogel with embedded Co3O4 nanoparticles (3D Co3O4-RGO aerogel) is prepared by means of a solvothermal approach and subsequent freeze-drying and thermal reduction. The obtained 3D Co3O4-RGO aerogel has a high specific capacitance of 660 Fg(-1) at 0.5 Ag-1 and a high rate capability of 65.1% retention at 50 Ag-1 in a three-electrode system. Furthermore, the material is used as cathode to fabricate an asymmetric supercapacitor utilizing a hierarchical porous carbon (HPC) as anode and 6m KOH aqueous solution as electrolyte. In a voltage range of 0.0 to 1.5 V, the device exhibits a high energy density of 40.65 Whkg(-1) and a power density of 340 Wkg(-1) and shows a high cycling stability (92.92% capacitance retention after 2000 cycles). After charging for only 30 s, three CR2032 coin-type asymmetric supercapacitors in series can drive a light-emitting-diode (LED) bulb brightly for 30 min, which remains effective even after 1 h.