Polypyrrole-modified graphene sheet nanocomposites as new efficient materials for supercapacitors

New polypyrrole (PPy)-graphene sheet nanocomposites have been synthesized after making reduced graphene react with tetrazine derivatives through inverse electron demand Diels-Alder reaction. The modified graphene material contains pyridazine units as demonstrated by X-ray photoelectron spectroscopy. Then this functionalized graphene material was coated on an electrode, and PPy was deposited by electrochemical polymerization. The obtained nanocomposites were characterized by FTIR, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), while the electrochemical performances were assessed by cyclic voltammetry, electrochemical impedance spectroscopy and charge-discharge experiments. Symmetrical coin cells were made to measure the capacitance in a two-electrode configuration. Polypyrrole-graphene nanocomposites with 40% PPy show the best electrochemical performances, with a very large capacitance per weight (326 F g−1 at 0.5 A g−1 and 250 F g−1 at 2 A g−1) and a small resistance due to a good ion accessibility, which makes it one of the best electrode materials for supercapacitors so far.