▎ 摘　　要

The optimized electric and ionic conductivity of metal oxides with pseudo-capacitive properties can greatly improve their electrochemical performances and can effectively amplify their applications in super-capacitors. Carbon spheres with multilayered graphene formed in their matrix are prepared by annealing them with sodium metal and they are combined with NiCo2O4 spheres by a simple hydro-thermal treatment. Structures and electrochemical performances of resulted samples are examined with X-ray diffraction, Raman scattering spectra, X-ray photoelectron spectroscopy, infrared spectroscopy, electron microscopy, gas physisorption, cyclic voltammetry and electrochemical impedance spectra, respectively. The largest specific capacitance of resulted composites is measured about 920 F g(-1) at 1 A g(-1), which is about 3.7 times larger than that of pure carbon spheres and 2.8 times larger than that of pure NiCo2O4 spheres. The formation of multilayered graphene in the matrix of carbon spheres not only increases the high specific capacitance based on electric double layers, but also makes metal oxides combined with them display greatly increased pseudo-capacitance. The electric and ionic conductivity of resulted composites with various weight ratios of NiCo2O4 and carbon spheres are respectively investigated and their effects on their electrochemical performances are also discussed. (C) 2018 Elsevier Ltd. All rights reserved.