Asymmetric supercapacitors based on a NiCo2O4/three dimensional graphene composite and three dimensional graphene with high energy density. Issue 47 (21st November 2016) - Sun, Shumin
Abstract : Asymmetric supercapacitors based on a NiCo2 O4 /3D-G composite and 3D-G show excellent supercapacitive performance with high energy density and long cycle life. Abstract : A NiCo2 O4 nanoparticle/three dimensional porous graphene (NiCo2 O4 /3D-G) composite was synthesized through a facile hydrothermal method combined with subsequent annealing treatment. X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy analyses indicate that the NiCo2 O4 nanoparticles were tightly anchored on the graphene sheets in the NiCo2 O4 /3D-G composite. When used as a supercapacitor electrode material, the obtained NiCo2 O4 /3D-G displayed a high specific capacitance of 2300 F g −1 at 1.0 A g −1 in 2.0 M KOH electrolyte. The asymmetric supercapacitor utilizing NiCo2 O4 /3D-G and 3D-G as positive and negative electrodes, respectively, delivered a high energy density of 73.8 W h kg −1 with a power density of 800 W kg −1 and long cycle stability (94.3% capacitance retention after 5000 cycles). The excellent supercapacitive performance of the NiCo2 O4 /3D-G can be ascribed to the synergistic effect of the porous and conductive three-dimensional cross-linking 3D-G and the high pseudocapacitive performance of the NiCo2 O4 nanoparticles.