Fabrication of flexible supercapacitor of Polypyrrole nanotubes embedded with Ruthenium oxide nanoparticles for enhanced electrochemical performance

Supercapacitors are ideal for flexible energy storage in wearable and portable electronics, but their low energy density limits practical uses. To overcome this, it is crucial to select and optimize the pertinent electrode materials carefully, besides their design configurations. In this study, we hypothesize that highly conductive polypyrrole nanotubes (PPy NTs), when effectively embedded with excellent pseudocapacitive ruthenium dioxide nanoparticles (RuO2 NPs), can be utilized to develop flexible electrodes with high specific capacitance and cyclic stability. Ultimately, these electrodes can be implemented in flexible solid-state supercapacitor devices with high power and energy density. We demonstrated the controlled in-situ growth of RuO2 NPs within the PPy nanotubular network, creating a porous framework with ample surface area. This structure effectively utilizes redoxactive sites, improving electrochemical performance, while maintaining high conductivity for enhanced chargetransfer kinetics. An optimized concentration of RuO2 precursor (75 wt%) resulted in a highly porous nanocomposite (NC) network with a reduced agglomeration of NTs leading to a larger surface area. Consequently, the flexible electrode of the optimized NC formulation exhibits a specific capacitance of 1496 mF cm(-2). A fabricated symmetric flexible solid-state device (FSSD) prototype exhibits a maximum areal capacitance and energy density of 772 mF cm(-2) and 86.78 mu Wh cm(-2), respectively. The fabricated device demonstrated consistent capacitive retention under various mechanical deformations, indicating its electromechanical stability. The FSSD was shown to illuminate a red LED with decent intensity for more than a minute, suggesting its potential applications in portable and wearable electronics.