Hybrid Organic Electrodes: The Rational Design and Synthesis of High-Energy Redox-Active Pendant Functionalized Polypyrroles for Electrochemical Energy Storage

In an effort to dramatically increase the capacity and electronic conductivity of organic-based redox active materials for electrochemical/electrical energy storage applications, polypyrrole (PPy) has been used as an anchoring backbone to form a family of dimethoxybenzene- (DMB-), bis(methylthio)benzene- (BMTB-), N, N, N', N' -tetramethylphenylenediamine- (TMPD-), and N, N, N', N' -tetramethylbenzidine- (TMB-) functionalized redox-active polymers. PPy was deliberately modified to provide an electronically conducting backbone with redox active pendants (RAPs) to enable immobilization (via electropolymerization) of the polymers onto current collectors. The RAPs dramatically increase the capacities of the materials by the reversible exchange of multiple electrons per formula unit. The electropolymerization of the pyrrole-anchored RAP monomers was achieved via cyclic voltammetry. The stability of the electropolymerized films was highly dependent upon the redox potential of the RAPs. The effects of charge density, during the electropolymerization process, were studied by varying the structure of the monomers. By the systematic characterization of the electrochemical properties of the electropolymerized films, the electrochemical behavior of these polymers provides validation of our targeted design to maximize the energy density of organic electrode materials for electrical energy storage applications.