A high-capacitance solid-state supercapacitor based on polyaniline and ground carbon fibers

Polyaniline tends to degrade in aqueous electrolytes and it can be alleviated using gel electrolytes. Here a low-cost solid-state supercapacitor of high energy density is fabricated with a facile method. The electrodes of the supercapacitor are made of a phytic acid-crosslinked freestanding film of polyaniline and ground carbon fibers and the electrolyte gel is composed of sulfuric acid and polyvinyl alcohol. Our results show that a maximum capacitance of 273.6 F/g (1.6 F/cm²) at a current density of 0.08 A/g can be achieved by the supercapacitor, which is significantly higher than most solid-state ones reported in the literature. The ability to achieve a high-capacitance supercapacitor with good cyclic stability is mainly attributed to excellent infiltration of the electrolyte gel into the electrodes. The developed lightweight, thin, flexible, and environmental friendly supercapacitor would have potential applications in various energy storage devices.