writer：H. Wei,a H. Gu,a (Contributed Equally) J. Guo, S. Wei, J. Liu and Z. Guo
keywords：Silica, Nano-polyaniline, Electrochemical Energy Storage
source：期刊
specific source：Journal of Physical Chemistry C
Issue time：2013年

     Phosphoric acid doped conductive polyainiline (PANI)/silica nanocomposites used as supercapacitor electrodes are tested in this article. The nanocomposites with 10.0, 20.0, 40.0, and 60.0 wt % silica nanoparticle loadings were synthesized via a facile surface initiated polymerization method. The morphology and chemical structure of the nanocomposites were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The electrochemical performances of the nanocomposites were evaluated by cyclic voltammetry, galvanostatic charge–discharge measurement, and electrochemical impedance spectroscopy techniques. The nanocomposites with a loading of 10.0 wt % silica nanoparticles displayed an optimum supercapacitive performances with a maximum gravimetric capacitance of 344.1 F/g at a scan rate of 5.0 mV/s (280.3 F/g for PANI nanoparticles) when normalized to the mass of PANI. Meanwhile, a maximum energy density of 37.4 Wh/kg (34.7 for pure PANI nanoparticles) at a power density of 430 W/kg (415 W/kg for pure PANI) is obtained from the charge–discharge measurement at a current density of 1.0 A/g. The effect of electrolytes on the electrochemical performances was also studied by using sulfuric acid and sodium sulfate in aqueous solution, respectively. A pseudocapacitance contribution was observed arising from PANI in the acid H₂SO₄ electrolyte medium whereas most of the capacitance came from the electric double layer capacitance in the neutral Na₂SO₄ electrolyte. In addition, external magnetic field was applied onto the nanocomposite electrode, which showed reduced capacitances due to the induced positive magnetoresistance. The cyclic stability studies revealed a much more superior stability of the nanocomposites than that of pure PANI after 500 charge–discharge cycles.