News
Graphite is a carbonaceous element mineral crystals, crystal lattice of its hexagonal layered structure, shown in Figure 1 - 1. The distance between each grid is 3.40, and the spacing of carbon atoms in the same network layer is 1 42A. Is the six party system, layered with complete cleavage. The cleavage surface is mainly composed by molecular bonding, weak on the molecular attraction, so the natural floatability is very good. Graphite soft, dark gray, greasy feeling, can pollute paper. Hardness of 1 to 2, along the vertical direction along with the increase of impurities can be increased from 3 to 5. Specific gravity is 1.9 to 2.3. Under the condition of isolated oxygen, its melting point is above 3000,…
Acid treatment is an oxidation process to graphite felt. Usually using concentrated sulfuric acid, nitric acid, potassium dichromate to modify the graphite felt.put the graphite felt into concentrated sulfuric acid and under boiling situation for 5h,then make it as electrode material for vanadium redox flow battery,it could make the energy efficiency increase to about 90%.the result of testing shows that after the treatment of concentrated sulfuric acid,it can reduce the electric resistance of the electrode material,and the electrochemical property of the graphite felt can increase with the concentration of the sulfuric acid.the number of the active group on the surface of graphite felt have an obvious increase. Some researchs showed that the graphite felt under the mixed acid and boiling…
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…
