3.6 V high-voltage symmetrical supercapacitor based on reduced graphene oxide/polythiophene aerogels with uniform dispersion

The low energy density of supercapacitor (SC) is considered as a major challenge for its use in intermittent renewable energy, smart grid and electric vehicles. General, those materials with high and low redox potentials are used as positive and negative electrodes respectively to fabricate asymmetric SC for higher voltage and energy density. The voltage and energy density of symmetrical SCs are usually lower than that of asymmetric SCs. This work uses a hydrothermal method to prepare reduced graphene oxide/polythiophene (RGO/Pth) aerogel with liquid-like polythiophene (L-Pth) as a precursor. The de-doping of L-Pth and π - π effect between Pth and graphene in hydrothermal process result in uniform dispersion of Pth on graphene. An aerogel with a specific surface area of 147.6 m2/g and a pore volume of 0.64 cm3/g was obtained. The RGO/Pth aerogels exhibits an oxidation potential up to 4.2 V (vs. Li/Li+ potential) attributed to the P-type doping of Pth (Pth + xPF6− ↔ Pthx+(PF6−)x + xe−) and a reduction potential as low as 0.6 V corresponding to the N-type doping of Pth (Pth + xLi+ + xe− ↔ Pthx-(Li+)x). Thus, the assembled RGO/Pth//RGO/Pth symmetrical SC shows an high-voltage of 3.6 V, an energy density of 66.1 Wh/kg at a power density of 900 W/kg and a capacitance retention of 80.2 % over 8000 cycles.