Comparison of structure and electrochemical properties for PANI/TiO 2 /G and PANI/G composites synthesized by mechanoche
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Polyaniline/nano titanium dioxide/graphene nanoplatelet (PANI/TiO2/G) composite was synthesized by mechanochemical route. The structure and morphology of the composite were characterized by Fourier transform infrared spectra, ultraviolet-visible absorption spectra, x-ray diffraction and transmission electron microscopy. The electrochemical performances of the composite were investigated by galvanostatic charge-discharge, cyclic voltammetry, cycling stability and electrochemical impedance spectroscopy. The structure and properties of PANI/TiO2/G composite were compared with that of polyaniline/ graphene nanoplatelet (PANI/G) composite prepared under the same polymerization conditions. After comparative analysis with PANI/G, the effects of the nano titanium dioxide (TiO2) on the structural and physicochemical properties of the PANI/G have been discussed in depth. The comparison suggested that the PANI/TiO2/G composite has higher oxidation degree and lower crystallinity than PANI/G due to the addition of nano-TiO2. Morphology studies showed that PANI and nano-TiO2 particles were both observed on the bent and flat surfaces of graphene nanoplatelet in the PANI/TiO2/G composite. The electrochemical tests showed that the PANI/TiO2/G composite displayed a higher electrochemical activity with specific capacitance of 516 F/g (3 mA/cm2) and better cycle stability than PANI/G.
I. INTRODUCTION
Supercapacitors have attracted considerable attention over the past few decades, owing to the high power density, high cycle efficiency, fast charge/discharge ability and a long cycle life compared with secondary batteries and conventional electrolytic capacitors.1,2 To develop an advanced supercapacitor device, an active electrode material with high capacity performance is indispensable. Conducting polymers have been considered as electrode materials in supercapacitors due to their ease of synthesis, environmental stability and highly controllable electrical conductivity. However, a low cycle life and poor mechanical properties of conducting polymers resulting from the swelling and shrinkage caused during the doping/dedoping processes usually lead to a decrease in the electrochemical performance.3–5 Of late, conducting polymers have been compounded with other fillers such as carbon materials to obtain composites as electrode materials; the cycle stability and capacitance value of carbon-based polymers are improved by synergistic effects between components.6–8
Address all correspondence to these authors. a) e-mail: [email protected] b) e-mail: [email protected] DOI: 10.1557/jmr.2013.23 832
J. Mater. Res., Vol. 28, No. 6, Mar 28, 2013
http://journals.cambridge.org
Downloaded: 02 Aug 2014
Polyaniline (PANI) is a promising electrode material because of its low cost, easy synthesis, simple acid-doping/ base-dedoping process and high capacitance, but its low electronic conductivity and poor cycle stability hinder its wide application in supercapacitors.9,10 Recently, the composites of PANI and carbon material have attracted considera
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