Well-organized polyaniline nanorod arrays on graphene oxide sheets constructed under flowing condition for flexible stable high-rate supercapacitors

The combination of polyaniline (PANI), especially nanoarrays and graphene sheets, has exhibited remarkable enhancement in capacitance performances of the composite electrodes. However, they still suffer from unsatisfied energy density, rate performance at high current densities, and cyclic stability, which could be enhanced by providing more electroactive sites and rapid kinetics of ion transport through the optimization of the structure and interface of electrodes. To improve the orientation degree of polymeric chains and open nanoarray structure, in situ hybridization under flowing condition was developed to continuously construct a well-organized array of PANI nanorods on graphene sheets. Due to the uniform structure, array nanostructures on substrates not only provide a larger electrochemically active surface area, faster electron transport, and superior ion diffusion but also possess a higher electrical conductivity and maintain a better structural mechanical stability. In addition, open structure can facilitate electrolyte diffusions, thus reducing the overall internal resistance. The composite electrode fabricated under optimized condition possesses a maximum capacitance of 562.3 F g⁻¹ at 1 A g⁻¹ with a retention rate of up to 90.9% from 1 to 100 A g⁻¹. Moreover, the assembled flexible device delivers a maximum energy density of 19.6 Wh kg⁻¹ at 400.0 W kg⁻¹ and a capacitance retention of 83.8% at 20 A g⁻¹ after 5000 cycles accompanied by low density and excellent mechanical properties. Such composite electrode materials can be believed to be a potential successor as flexible stable high-rate supercapacitors for wearable and foldable devices.