A graphene/carbon nanotube@π-conjugated polymer nanocomposite for high-performance organic supercapacitor electrodes

Abstract

Supercapacitors based on π-conjugated conducting polymers have attracted attention due to their high pseudo-capacitance characteristics. However, the narrow window of their potential (<1 V) gives rise to low energy density, and this restricts their practical application. In the present study a novel hierarchical nanocomposite, graphene nanosheets/acid-treated multi-walled carbon nanotube-supported poly(1,5-diaminoanthraquinone) (GNS/aMWCNT@PDAA), has been successfully synthesized using cerium sulphate (Ce(SO₄)₂) as oxidant and camphor sulphonic acid as dopant. The nanocomposite exhibits a unique nanoporous morphology, a high π-conjugated degree and an excellent conductive interpenetrating network. With these intriguing features, in addition to its unique p- and n-doping characteristics, the supercapacitor in a 1 M tetraethylammonium tetrafluoroborate -acetonitrile (Et₄NBF₄-AN) electrolyte can be reversibly cycled within a potential window of 2.8 V. The supercapacitor achieves a high energy density of 86.4 W h kg⁻¹ at a power density of 0.73 kW kg⁻¹, and still retains energy density of 55.5 W h kg⁻¹ at a power density of 153.9 kW kg⁻¹. In addition, superior cycling stability is achieved, with only 7% capacitance loss after 10 000 cycles. This excellent performance surpasses that of other recently reported supercapacitors and represents a significant breakthrough in π-conjugated polymer-based supercapacitors.