Wen Li's research while affiliated with Xiangtan University and other places

A novel doped activated carbon has been prepared from H2SO4-doped polyaniline which is prepared by the oxypolymerization of aniline. The morphology, surface chemical composition and surface area of the carbon have been investigated by scanning electron microscope, X-ray photoelectron spectroscopy and Brunaner–Emmett–Teller measurement, respectively. Electrochemical properties of the doped activated carbon have been studied by cyclic voltammograms, galvanostatic charge/discharge, and electrochemical impedance spectroscopy measurements in 6moll−1 KOH. The specific capacitance of the carbon is as high as 235Fg−1, the specific capacitance hardly decreases at a high current density 11Ag−1 after 10,000 cycles, which indicates that the carbon possesses excellent cycle durability and may be a promising candidate for supercapacitors.

Nickel-embedded carbon nanofibers were prepared by the processes of stabilization and carbonation after electrospinning a mixture solution of nickel acetate and polyacrylonitrile in N,N-dimethylformamide. The surface morphology and structure of composites were examined by scanning electron microscope (SEM) and X-ray diffraction (XRD). Compared with performances of composite electrodes with different mass ratios of nickel and carbon by cyclic voltammetry (CV) and chronopotentiogram test, the results show that the introduction of a proper proportion of nickel into carbon could enhance both specific capacitance (SC) and electrochemical stability. The specific capacitance of the carbon nanofiber electrode without the Ni loading was 50 F/g, while that of 22.4 wt.% Ni/carbon electrode increased to 164 F/g. The improved specific capacitance may be attributed to synergic effects from each pristine component, and the electrochemical catalysis effect of nickel.

Nanostructured nickel–manganese oxides composite was prepared by the sol–gel and the chemistry deposition combination new route. The surface morphology and structure of the composite were characterized by scanning electron microscope and X-ray diffraction. The as-synthesized NiO/MnO2 samples exhibit higher surface area of 130–190m2g−1. Cyclic voltammetry and galvanostatic charge/discharge measurements were applied to investigate the electrochemical performance of the composite electrodes with different ratios of NiO/MnO2. When the mass ratio of MnO2 and NiO in composite material is 80:20, the specific capacitance value of NiO/MnO2 calculated from the cyclic voltammetry curves is 453Fg−1, for pure NiO and MnO2 are 209, 330Fg−1 in 6molL−1 KOH electrolyte and at scan rate of 10mVs−1, respectively. The specific capacitance of NiO/MnO2 electrode is much larger than that of each pristine component. Moreover, the composite electrodes showed high power density and stable electrochemical properties.