Authors: C. Lei, C. Lekakou
Affilation: University of Surrey, United Kingdom
Pages: 176 - 179
Keywords: supercapacitors, EDLC, carbon
Supercapacitors are electric devices with power and energy densities between those of a traditional capacitor and battery. As the demand for energy storage devices with high power and long durability increases, the supercapacitor becomes more and more important. An electrochemical double layer capacitor (EDLC) consists of two electrodes, a separator and an electrolyte, so that it effectively forms two capacitor layers, which means increased capacitance and lower material cost. Furthermore, an EDLC supercapacitor differs from a traditional capacitor in that its electrodes are composed of a large surface area conductor such as activated carbon, and it accumulates the opposite charges on the thin layer of electrode/electrolyte interface via electrostatic force or non-faradaic effect, so that it possesses a huge capacitance (> 100F/g), and has higher power and much longer cycle lifetime (>100000 cycles) than rechargeable batteries. The processing of carbon electrodes plays an important role in its final electrical performance. UV treatment is much simpler and cheaper compared with other physical and chemical activation methods. In this report, a series of carbon based symmetric electrodes for EDLC were explored, using commercial, activated carbon materials or carbon nanomaterials. UV light treatment was also used. The performances of organic electrolytes based on LiPF6 or Et4NBF4 in mixed solvents were also explored, which have an electrochemical window of more than 3V. A VersaSTAT MC analyser was used to carry out impedance spectroscopy, cyclic voltammetry, and galvanostatic charge-discharge tests on the devices.