Lead-modified graphite felt electrode with improved VO²⁺/VO₂⁺ electrochemical activity for vanadium redox flow battery

Graphite felt is disadvantageous of lower electrochemical reaction activity, which is improved by introducing catalysts. Especially, cheaper materials and simple fabrication are popular for reducing cost. In this work, electrodeposited-lead electrode is proposed for improving electrochemical reaction activity of VO²⁺/VO₂⁺ couple as well as charge-discharge performance of the battery. Experiment platform is established for vanadium redox flow battery. Cyclic voltammetry and charge-discharge performance measurements are carried out. Electron scanning microscope (SEM) is employed to investigate the surface morphology of electrode. Results show that peak potential difference (ΔE₊) and peak current ratio (I_a+/I_c+) with electrodeposited-lead electrode is 103.7 mV lower and 0.249 lower than that with untreated electrode for VO²⁺/VO₂⁺ electrochemical reaction. Electron scanning microscope images exhibit that lead particles are adhered extensively on carbon fiber of electrodeposited-lead electrode, which improves electrochemical activity of VO²⁺/VO₂⁺ couple. Energy efficiency of the battery with electrodeposited-lead electrode in positive side is higher than that with untreated electrode by 8.5% at 60 mAcm⁻². Electrodeposited-lead electrode exhibits higher activity to VO²⁺/VO₂⁺ reaction and brings about higher energy efficiency of battery. This work provides a suitable electrode for vanadium redox flow battery.