Embodiments of the presently disclosed technology provide a synergistic combination of a conjugated open-shell donor-acceptor polymer with a carbon-based compound (e.g., reduced graphene oxide) to produce a composite electrode material which demonstrates state-of-the-art capacitance and potential window, with excellent kinetics and cycle life. The conjugated open-shell donor-acceptor polymer may comprise a plurality of alternating electron-rich monomers (i.e., donors) and electron-deficient monomers (i.e., acceptors) bonded together via a conjugated backbone. The conjugated backbone may comprise a connection of n-orbitals of the plurality of monomers in alternating single and double bonds that facilitates unpaired electron delocalization—thereby stabilizing charge for the polymer. The carbon-based compound of the composite electrode material may provide porous, conductive scaffolds for the composite electrode material, resulting in electrodes scalable to microns-thick films with fast kinetics.