Catechols are of great interest as cathode materials for energy storage due to the combination of high capacity and redox potential. However, pristine catechols possess poor electrical conductivity and dissolution stability. We propose a sulfonated polycatechol SPVQ with a high molecular mass, which can be used as an anionic redox-active dopant for the electrochemical deposition of poly(3,4-ethylenedioxythiophene) (PEDOT). Proposed polycatechol is designed to maximize the theoretical capacity as much as possible for the polymer bearing both catechol and sulfonate functionalities. The composite polymer shows an improved capacity due to the two-electron faradaic process of SPVQ compared to PEDOT:PSS (49 mA h g −1 vs 21 mA h g −1 ) and, being deposited on a carbon fiber, affords an areal capacitance of 264 mF cm −2 versus 87 mF cm −2 for PEDOT:PSS. Coulombic anchoring of SPVQ in the PEDOT matrix resulted in increased cycling stability of the material (70% capacity retention after 100 cycles and 35% after 1500 cycles). Scanning electron microscopy, operando spectroelectrochemical, and microgravimetric methods reveal a great impact of the polyanionic dopant structure on the morphology, ionic transport, and finally electrochemical performance of the composite material. The obtained results demonstrate the importance of fine tuning of the composition and morphology of the composite materials to ensure optimal interactions between the redox/anionic and conductive components.