The graphite felt used for vanadium redox flow battery need to be modified,to improve the chemical activity,and find out the influence factors in graphite felt electrode,we could use different treatments on the graphite felt electrode material. Below treatments are heating treatment and acid treatment,we use polarization curve, cyclic voltammetry and AC impedance to describe the electrochemical properties of the graphite felt electrode,and describe the differences between the chemical treatment before and after,and we need to use XPS,SEM and
There are different ways to treat the graphite felt electrode,such as : heating treatment,acid treatment, electrochemical treatment,etc.
Put the PAN graphite felt on the crucible and put it into the muffle furnace,under the 500 C°,after 0.5 h calcinations,make it natural cooling;and on the other hand,put the graphite felt into 85 C°concentrated acid,and after 4 hours immersion,then use the distilled water to make it clean.
After polarization curve analysis,we could find that the corrosion current of untreat graphite felt electrode is highest,and the polarization resistance of it is the lowest. As for the heating treatment and acid treatment graphite felts,they are almost the same,and two times higher than the untreat one. The result show that the corrosion resistance of treated graphite felt is better than the untreated ones,and the acid treatment graphite felt is the best of all.
After cyclic voltammetry,the result shows that the reactive activity and reversibility of the acid treatment is better than the heating treatment and the untreated graphite felts. The SEM result shows that,the heating treatment can make cause surface damage of the carbon fiber,so it will make the resistance more higher,however,after acid treatment,the acid can make the carbon fiber surface smoothly,it will also make the resistance increase. Although the resistance will increase after acid and heating treatment,but it will not have any influence on the reactivity and reversibility.