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 were characterized by scanning electron microscopy, electrochemical impedance spectroscopy, cyclic voltammetry and galvanostatic charge/discharge. Results indicate that there are strong adhesive forces between 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 8.3mF/cm2 at a discharge current of 1mA and their retention rates after 5000 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.