Fabrication of Solid-State Asymmetric Supercapacitors Based on Aniline Oligomers and Graphene Electrodes with Enhanced Electrochemical Performances

This work describes solid-state asymmetric supercapacitors (ASCs), composed of aniline oligomers as a cathode, nonoxidative graphene sheet as an anode, and polyvinyl alcohol-potassium hydroxide gel as an electrolyte. The synergistic effects resulting from the combination of aniline oligomer and graphene sheet have greatly enhanced the electrical and electrochemical performance of ASCs. The electrical and electrochemical properties of ASCs were highly dependent on the protonation levels of aniline oligomers including aniline tetramer, aniline trimer, and aniline dimer. The aniline tetramer with an appropriate chain length provided higher carrier transport within the anode compared to that of the aniline dimer and trimer. The water-dispersible graphene (WDG) sheets greatly enhanced structural stability and cycle life of aniline tetramers by alleviating swelling, chain scission, and shrinking of the aniline tetramers. The ASC composed of aniline tetramer/WDG sheet exhibited high areal capacitance (62.2 mF/cm(2)), volumetric capacitance (207.4 F/cm(3)), and good cycling stability (97.2% after 2000 cycles and 90.4% after 10 000 cycles). The strategy presented in this work is simple and facile, which would give an insight into efficient ways for applying aniline tetramers and graphene sheet for state-of-art electronic applications.