Asymmetric and symmetric supercapacitors based on polypyrrole and activated carbon electrodes

Supercapacitors were prepared using either two polypyrrole (PPy) composite electrodes or one PPy composite and one activated carbon electrode. The PPy composite electrodes were either freestanding paper-like sheets or PPy films printed on graphite ink coated aluminium/PET laminate substrates, using Cladophora algae derived cellulose as the substrate or binder, respectively. The specific capacitance of the PPy electrodes was found to be about 200 F g^-1 depending on the manufacturing method, yielding supercapacitors with capacitances between 0.45 and 3.8 F and energy efficiencies of over 90%. For an asymmetric device with activated carbon positive electrode and PPy negative electrode a capacitance loss of 5% was seen after 14300 cycles.