Although the density of carbon fiber is lower than that of aluminum, its strength is higher than that of steel. Carbon fiber is not only the inherent "hard" characteristic of carbon materials, but also the machinability of textile fiber.
A carbon fiber woven graphite felt has good conductivity, mechanical properties, electrochemical reaction activity, acid resistance, corrosion resistance and oxidation resistance, is a good electrode material, compared with metal, graphite powder and various electrode materials, more suitable for the electrode storage battery.
At present, the domestic production of graphite felt is mainly used to make thermal insulation material, and its conductivity and electrochemical activity can not meet the requirements of the use of battery electrode materials, therefore, the need for carbon fiber felt surface treatment. The commonly used surface treatment methods include heat treatment, acid treatment and electrochemical oxidation treatment.
The operation of heat treatment in air atmosphere, and after the heat treatment,the conductive ability of graphite felt has been improved, in the heat treatment of graphite felt, if the temperature is too low, resulting in electrochemical active graphite felt low, unable to meet the requirements of use as electrode materials; but if the heat treatment temperature is too high, it will cause the graphite felt surface etching, serious excessive oxidation, fiber breakage and breakage, resulting in the the electrical conductivity and mechanical properties decreased sharply, seriously affecting their life.
With the heat treatment temperature increased gradually from 450 degrees to 600 degrees Celsius, the impurities of graphite felt surface are gradually disappear, with the further oxidation of the holes, grooves and other defects; carbon fiber structure with the oxidation degree also changed gradually from the turbostratic structure of two dimensional ordered structure transformation three.