Ternary nanocomposites of PEDOT: PSS, RGO, and urchin-like hollow microspheres of NiCo2O4 for flexible and weavable supercapacitors

This work reports the binder-free synthesis of development of on activated carbon fiber (ACF) based electrodes coated with a ternary composite material composed of PEDOT: PSS, reduced graphene oxide (RGO), and NiCo2O4@RGO (N@R) microspheres (i.e. ACF/PR-N@R) using simple chemical processes, and hence the effect of hollow and solid urchin-like morphologies of N@R microspheres on their electrochemical behavior. The electrode prepared with hollow microspheres exhibits significantly improved electrochemical properties with a volumetric specific capacitance of 5270 mF/cm3 at 0.10 A/g due to better surface area, porous hierarchical nanostructure, and the synergistic effects between ternary composite components. In contrast to other pseudocapacitive components that serve as fillers to prevent the restacking of graphene sheets, the electrochemical responses of electrodes dominated by RGO contribute to the electrical double layer capacitance (EDLC) behavior. Assembled in a twisted configuration with two gel electrolyte coated optimum electrodes, the symmetric fiber-shaped supercapacitor (FSC) exhibited areal energy and power densities of 25.6 μWh/cm2 and 99.5 μW/cm2 at 0.10 A/g, respectively. When woven into woolen fabric in series connections to power red LEDs, the FSC demonstrated outstanding electrochemical stability under various deformations. The electrochemical results demonstrate the ternary composite's potential as a possible electrode material for weavable supercapacitors.