Electrode is one of the key materials of the liquid flow battery, the main function is to provide the electrochemical reaction place, and it has a certain catalytic effect. Polyacrylonitrile (PAN) based graphite felt by numerous graphite fibers, the real surface area is far greater than the geometric surface area, good electrical conductivity, graphite fiber is small, the number of unsaturated carbon atoms in the fiber surface edge and the edges and corners, widely used as electrode materials for liquid flow.
Wind energy, solar energy, tidal energy and other green pollution-free renewable energy development and utilization, so that high efficiency, long life, low cost of large-scale efficient storage battery energy storage equipment is particularly important.
The active specific surface area of graphite felt is small, the ability is poor, and its surface activity is lower, and its practical application is limited, so it is necessary to carry out surface modification to meet the requirements of good electrode materials.
The main method is: deposition, air oxidation, liquid phase oxidation, plasma oxidation, electrochemical oxidation, carbon nanotube modified method, which is simple in the air oxidation process, oxidation time and oxidation temperature is easy to control, easy to realize industrialization.
The optimum heat treatment of graphite felt oxidized in the air temperature is 550 DEG C; 550 degrees of heat treatment after 5 h, the pits in the surface of graphite fiber increased significantly enhance the number of surface oxygen containing functional increased; electrode performance can be improved, the current efficiency of battery voltage efficiency reached 94.60%, reached 85.36%, energy efficiency reached 80.75%; charge discharge resistance reduce battery.
To improve the performance of the electrode due to air oxidation, fiber surface area increased, the number of surface active nodes is increased; in addition, the increase of fiber surface oxygen, reduces the charge transfer resistance of electrochemical reaction.