Co3O4 anchored on meshy biomass carbon derived from kelp for high‐performance ultracapacitor electrode

In this paper kelp was used as the carbon precursor to prepare a biomass carbon with meshy microstructure, and Co 3 O 4 nanoparticles were further modified on the meshy biomass carbon (MBC) by using solvothermal and pyrolysis methods. The prepared Co 3 O 4 @MBC composite combined the special structure of MBC with uniformly distributed Co 3 O 4 nanoparticles, which provided large specific surface and good conductivity. Different methods including scanning electron microscopy, transmission electron microscopy , X-ray powder diffraction, Raman spectroscopy , X-ray photoelectron spectroscopy and nitrogen adsorption-desorption were used to characterize the structure and performances of composite. Co 3 O 4 @MBC composite was used to construct an electrode for supercapacitor , which had better electrochemical performance than that of pristine Co 3 O 4 nanoparticles and MBC electrodes. The highest specific capacitance (1212.4 F g −1 at 0.5 A g −1 ) could be obtained with excellent cycle stability and the capacity retention was 99.5% at 2 A g −1 after 2000 cycles, which could be attributed to synergistic effects of both pseudocapacitance and electric double layer capacitance under optimized carbon-cobalt ratio. Furthermore, an asymmetric supercapacitor system was constructed utilizing Co 3 O 4 @MBC as positive electrode with MBC as negative electrode. This two-electrode system provided a good performance with energy density of 59.82 Wh·kg −1 at a power density of 700 W kg −1 , highlighting the potential application in efficient energy storage device.