Creating 3 dimensional foam morphology of lead dioxide on the polyaniline film for improving the performance of lead flow batteries

Abstract

In the present study, we investigate the effect of polyaniline as a conductive surface modifier on the morphology of the lead dioxide, PbO2, as a positive active material of lead-acid redox flow batteries. We used cyclic voltammetry to electrodeposit PbO2 on the surface of the bare and polyaniline-modified graphite substrates. We characterized the morphology and crystal structure of the electrodeposited PbO2 film using X-ray diffraction and scanning electron microscopy. In addition, we used electrochemical polarization and electrochemical impedance spectroscopy techniques to investigate the kinetics of the lead dioxide charge transfer in the presence and absence of polyaniline. To analyze the effect of the polymer film on the battery performance, we discharged the cells at different rates, and studied the cycle life of the cells. The results show that lead dioxide adopts an interconnected 3D fiber-like morphology on the surface of the polyaniline-modified graphite, resulting in a higher surface area, a better cycle life, and a higher coulombic efficiency, along with a retarded short-circuit problem. Besides, polyaniline modification increased the electron transfer rate of lead dioxide, reduced the internal resistance, enhanced the discharge plateau with less oscillation in the voltage range from 1.4 to 1.6 V, and increased the average specific power up to 367 mWg−1, resulted in a generally boosted battery performance.