Electrochemical Performance of Transition Metal-Coordinated Polypyrrole: A Mini Review.

The conductive polymer of polypyrrole can be acted as electroactive electrode material of supercapacitor due to reversible redox behavior and high capacitance. It usually suffers from low electrochemical stability due to the breakdown of polymer molecule chain in the long-term charge and discharge process. The monometallic or bimetallic-coordinated polypyrrole usually exhibits the improved electrochemical performance. The transition metal ions such as ruthenium, iron, copper and cobalt are adopted for the coordination modification. The transition metal-coordinated polypyrrole includes the intrachain and interchain coordination structure between transition metal ion and nitrogen atom of pyrrole ring. It is able to reinforce the polymer molecule chain strength to overcome excessive volumetric swelling and shrinking during charge-discharge process, improving the cycling stability and rate capability of polypyrrole. Accordingly, the transition metal-coordinated polypyrrole keeps simultaneously high capacitance performance and electrochemical stability, acting as the promising conductive polymer-based supercapacitor electrode material for effective energy storage.