At present , the electrode material of vanadium redox battery are mainly graphite felt and carbon felt. Graphite felt is fired under the high temperature and has high degree of graphitization; carbon felt is in low baking temperature and in low degree of graphitization relatively. The conductive properties of the two felts are different, the price is different. How to choose which kinds of electrode material depends on the design of the vanadium redox battery stack. The good electrode material can increase the current density of vanadium redox battery, and it can protect the the bipolar plate from corrosion.The technical content is not high, but different manufacturers of the vanadium redox battery need find and test the graphite/carbon feltproducts from different manufacturers according to their own design of vanadium redox battery , it will take some time.
 
  Why we must use the graphite felt or carbon felt as the electrode material of vanadium redox battery ? As we known, the previous polysulfide battery and zinc bromine battery don’t use them. Well, some cases will happens if vanadium redox battery don’t use graphite/carbon felt electrode material : you will find a very low current density of vanadium battery, probably only 20mA or lower (the current density is 80mA per square centimeter when we use graphite felt or carbon felt ); and you will find that the carbon plate which used as the bipolar plate will die quickly and the life of vanadium redox battery will be very short. So the electrode material must be carbon felt / graphite felt in the current system of vanadium redox battery.
 
  The significant difference between graphite felt and carbon felt are cost and price. The same raw materials, The temperature increase several hundred degree when the graphite felt is processed , the electricity will consume more ,on the other hand, the final product weight is light relatively, obviously,the price will be higher.
 
  The graphite felt / carbon felt can be divided into two categories of PAN based and viscose based mainly in accordance with the different raw materials. PAN based raw materials are cheap relatively , Rayon based is more expensive. The difference on the performance depends on how the design of the vanadium redox battery systemt .