In situ polymerization of EDOT onto sulfonated onion-like carbon for efficient pseudocapacitor electrodes

Abstract

Conductive polymers (CPs) and carbon nanoparticles are attractive active materials for binder free supercapacitor electrodes. A composite of these components combines high pseudocapacitance of CPs with the mechanical stability of carbon particles. Homogeneous percolation of both materials in the composite is fundamental for electrochemical performance but is typically hindered due to insoluble starting materials. Here, we propose a template assisted polymerization of 3,4-ethylenedioxythiophene (EDOT) onto sulfophenylated onion-like carbon (SPOLC). Besides providing dispersibility for the carbon particles, anionic functionalization also promotes the mechanical and electrical connection between PEDOT and SPOLC. The resulting composite precipitates as a viscoelastic aqueous slurry enabling direct processing to binder-free supercapacitor electrodes. The synergistic combination of mechanical and electrochemical properties in the composite leads to a specific capacitance of 77 F g⁻¹ and a capacitance retention above 90% after 70 000 cycles. Our findings highlight how the functionalization of carbon enhances dispersibility in water and provides connectivity with the CP, thereby boosting the performance and stability in supercapacitor applications.