Redox-active supercapacitor electrode from two-monomer-connected precursor (Pyrrole: Anthraquinonedisulfonic acid: Pyrrole) and sulfonated multi-walled carbon nanotube

Abstract

An ordered redox-active polymer composite from a two-monomer-connected precursor (TMCP) and sulfonated multi-walled carbon nanotube (S-MWCNT) was prepared as a supercapacitor electrode material. TMCP, pyrrole: anthraquinonedisulfonic acid: pyrrole (Py:AQDSA:Py), in which anthraquinonedisulfonic acid (AQDSA) is connected to two pyrrole (Py) monomers, restricts chain entanglement during polymerization. The crystalline P(Py:AQDSA:Py)-S-MWCNT composite was formed when the TMCP (Py:AQDSA:Py) was polymerized on S-MWCNT. The crystalline polymer composite was analyzed by high-resolution transmission electron microscopy and X-ray diffraction. The specific surface area of as-optimized TMCP-based redox-active polymer composite was very high (62 m2 g−1) compared to TMCP polymer. The morphology of the resulting composite showed that TMCP polymerized uniformly over the S-MWCNT surface to form an interconnected network of redox-active TMCP polymer that increases the redox sites, with S-MWCNT promoting ionic transport. The redox-active P(Py:AQDSA:Py)-S-MWCNT composite delivered a specific capacitance of 397 F g−1 (1 A g−1) in a 0.5 N sulfuric acid and excellent capacity retention of 98.8% after 2500 cycles. These results highlight the potential use of redox-active TMCP-based composite as an active material for electrochemical energy storage systems.