Preparation and performance of carbon/polypyrrole membranes as an electrode in supercapacitors

Three membrane electrodes for supercapacitors in micro-electro-mechanical-systems( MEMS) were made of polypyrrole( PPy),carbon nanotube/polypyrrole( CNT/PPy) and graphene/polypyrrole( GR/PPy) electrodeposited on current collectors.The samples w ere characterized by scanning electron microscopy,electrochemical impedance spectroscopy,cyclic voltammetry and galvanostatic charge/discharge.Results indicate that there are strong adhesive forces betw een the electrode materials and the current collectors.The electrode resistances decrease in the order of PPy,CNT/PPy and GR/PPy.The specific capacitances are 7.0,8.0 and 8.3 mF/cm2at a discharge current of 1 mA and their retention rates after 5 000 charge/discharge cycles are 72.9,85.0 and 89.2% for PPy,CNT/PPy and GR/PPy,respectively.The electrochemical performance and stability of the MEMS supercapacitors are improved significantly by adding CNTs or graphene to PPy.