Electropolymerized Polypyrrole Nanocoatings on Carbon Paper for Electrochemical Energy Storage

A highly electrically conductive and uniform polymer film containing small, evenly sized particles was potentiodynamically electropolymerized at a slow scan rate of 50mVs(-1), as compared to the strongly agglomerated and low-conducting films obtained at higher scan rates of 100 and 200mVs(-1). Cyclic voltammetry and galvanostatic charge-discharge experiments demonstrated a higher areal capacitance, energy density, and power density in the former material. The superior supercapacitive performance was studied by electrochemical impedance spectroscopy (EIS) and can be explained by both a higher electrical conductivity and a facilitated charge transfer in the redox reactions occurring in the former electrode. This work suggests the possibility of fabricating polypyrrole (PPy) pseudocapactive electrodes with high performance via a facile potentiodynamic synthesis at low scan rates. Meanwhile, it provides an alternative to introducing surface functionalities of conductive polymers onto the carbon paper.