The graphite felt used in the vanadium redox flow battery need a treatment to make it have a larger specific surface area,more oxygen functional groups and lower electronic resistance,by these ways to improve the electrochemical property.
The main ways to improve the graphite felt include:heat treatment,acid treatment,electrochemistry treatment etc.In addition to those single method,it also has comprehensive treatment of the graphite felt.
To the Pan base graphite felt,after 5h of concentrated sulfuric acid environment,and then make it in the 450℃ environment for 2h,the results show that it could increase the electrochemical property of the electrode material in the V4+ solution.by the testing of SEM,the impurity on the surface of the graphite felt is removed,and the number of the surface active group obviously increased.
Using chloro-iridic aicd treat the graphite felt which is treated with heating and acid treatment,the graphite felt show a good electrochemical property and reversibility.It can make the vanadium battery pack more efficient.the main reason mostly is acid treatment after heating can further improve the electrochemical property.
Except for the treatment above,there are also surface metallization, ammoniation etc. There are all kinds of ways to treat the graphite felt and to make it more activity,but the way is still need to improve,if the graphite felt could be used for commercial process,it must has a high property and low cost,so we still need to find out a way to achieve this purpose.The modification method of graphite felt is a major development direction of the electrode material in the vanadium redox flow battery.