Polypyrrole/carbon supercapacitor electrode with remarkably enhanced high-temperature cycling stability by TiC nanoparticle inclusion

In the potential applications for electric vehicle and stand-alone renewable energy storage, supercapacitors are likely to constantly operate at elevate temperatures, and yet the study on high-temperature cycling behavior of conducting polymer-containing supercapactors is scarce. Polypyrrole (PPy) film, doped with p-toluenesulfonate, has been coated onto activated carbon (AC) electrode preform. Although the specific capacitance of the electrode is doubled, from 176 F/g to 352 F/g, with coating of 17.7 wt.% PPy, the capacitance lost nearly 60% after 10,000 cycles at 40 degrees C, in contrast to 20% loss at 25 degrees C. It is demonstrated that the problem of accelerated fading at high temperature is effectively alleviated, in conjunction with significant (up to 50%) improvement in power performance, by embedding conductive TiC nanoparticles within the PPy layer via co-electroplating. With addition of 1.7 wt% of TiC in the composite electrode, the capacitance retains 92% of its initial capacitance under the same cycling condition (40 degrees C, 10,000 cycles). The enhanced high-temperature cycling stability has in part been attributed to the reduction in the mismatch of thermal expansion coefficient between the conducting polymer layer and the AC substrate. (C) 2012 Elsevier B.V. All rights reserved.