Poly(3-methyl thiophene)-graphene nanocomposites for asymmetric supercapacitors

[Display omitted] •Poly(3-methylthiophene) (P3MT)- graphene platelets (GNPs) nanocomposites prepared chemically.•Morphology studies show coating of P3MT over GNPs with unique open channel structure.•Nanocomposites show synergistic increase in specific capacitance.•Asymmetric supercapacitors based on P3MT-GNPs nanocomposites and activated carbon fabricated with optimized mass loading.•Supercapacitors exhibit enhanced rate capability and electrochemical stability. Poly(3-methyl thiophene)(P3MT)–graphene nanoplatelets(GNPs) nanocomposites were investigated for the application in supercapacitors. P3MT-GNPs nanocomposites were prepared by chemical polymerization and characterised by HR-TEM, FEG-SEM, TGA, Raman spectroscopy, XRD and electrochemical methods. Nanocomposites showed a morphology in which a thin layer of P3MT coating existed over GNPs with unique open channel pattern. Electrochemical characterisation of nanocomposites carried out in 1 M tetraethylene ammonium tetrafluroborate salt (TEABF4) in propylene carbonate (PC) showed synergistic increase in specific capacitance. Nanocomposites at higher concentration of the GNPs showed higher percentage of increase in specific capacitance. The nanocomposites were used as positive electrode while activated carbon AC was used as negative electrode in an asymmetric supercapacitor. The supercapacitors were fabricated with optimized mass ratio of positive active electrode material and negative active electrode material. The P3MT-GNPs/AC supercapacitor having P3MT/GNPs wt. ratio of 75/25, in the nanocomposite exhibited a specific capacitance of 30.5 Fg−1 with respect to the total active material of the supercapacitor cell. Supercapacitors showed high rate capability and low internal resistance due to the presence of GPNs in P3MT. The stability of the supercapacitors containing nanocomposites was found to be higher than the supercapacitors containing pristine materials. The observed results are attributed to the unique morphology of the nanocomposites.