Construction of activated-CNT/carbon composite aerogel for supercapacitor electrode with ultra high cycle stability

Double layer supercapacitors are widely used for energy storage devices due to their excellent characteristics such as high stability and good cycling performance. In this work, a novel carbon aerogel doped with activated short multi-walled carbon nanotube (CA/AMWCNT composite aerogel) was constructed by sol-gel and carbonization process. The effects of the activated short multi-walled carbon nanotube (AMWCNT) addition amount on the microstructure and electrochemical properties of the composite aerogels were investigated. The composite aerogels with appropriate AMWCNT addition amount exhibited improved specific surface area, pore diameter and pore volume. In particular, the composite aerogel CA/AMWCNT-2.5, with higher specific surface area (640 m2 g−1) and pore volume (1.985 cm3 g−1), exhibited improved electrochemical performance with the equivalent series resistance and specific capacitance at a current density of 1 A g−1 being 0.36 Ω and 115.11 F g−1, respectively. Moreover, the composite aerogel CA/AMWCNT-2.5 electrode showed excellent cycle stability, with the retention rate maintaining 99.9 % even after 10,000 cycles, and three prepared symmetrical supercapacitors could supply power for a light emitting diode bulb for a long time. This work provides a new strategy for developing electric double layer supercapacitors with ultra high cycling stability, and the obtained CA/AMWCNT composite aerogels will have promising applications in the field of energy storage devices that require a long service lifetime.