Electrochemical behavior of polyurethane ether electrolytes/carbon black composites and application to double layer capacitor

The thermal and electrochemical properties of polyurethane electrolyte/carb on black composites have been studied. The material structure presented amo rphous features and the electrical response was described in terms of equiv alent circuits accounting for the different relaxation processes occurring in the medium. The conductivity behavior did not fit satisfactorily either the effective medium theory or conventional percolation models. Flexible el ectrochemical capacitors using the composite as active material in associat ion with large area collectors have been built and tested. The performance of the capacitors were characterized by a variety of electrochemical techni ques, including impedance spectroscopy, cyclic voltammetry, galvanostatic c harge-discharge methods, and long term cycling tests. The device prepared w ith composite electrodes containing 20 wt% of carbon black exhibited a capa city of 0.7 F cm(-3) under 2 V providing an energy density of 0.4 W h 1(-1) . (C) 2001 Elsevier Science Ltd. All rights reserved.