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Effect of heat treatment temperature on the conductivity of graphite felt

  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, it needs surface treatment on the for graphite felt .Commonly used surface treatment methods include heat treatment, acid treatment and electrochemical oxidation treatment.

  The operation of heat treatment in air atmosphere, and the heat treatment after carbon fiber conductive ability has been improved, but there is no deep research on revealing fiber structure changes and conductive ability of the report.

  The surface morphology and structure of carbon fiber felt changed before and after heat treatment, and the conductivity of the carbon fiber felt was also affected. The mass loss of carbon fiber felt was slow at the beginning, and gradually increased when the temperature exceeded 450 degrees celsius.

  This is because oxygen started contact with graphite felt when exposed to only the surface of some active substances, the reaction is slow; with the reaction, oxygen gradually exposed to the fiber body, which is also affected by the oxidation erosion, the integrity of the fiber was damaged.

  In the heat treatment of graphite felt, if the temperature is too low, with active keys C-O and C=O activity were lower than the proportion of the surface area, leading to electrochemical active carbon fiber 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 carbon fiber mat surface etching is serious, excessive oxidation, fiber breakage and breakage, resulting in the electrical conductivity and mechanical properties decreased sharply, seriously affecting their life.

  There is no surface of carbon fiber graphite felt after heat treatment. The texture is clear, can be observed in some small, parallel to the fiber axis etching grooves and other defects, these defects are mainly due to the formation of polyacrylonitrile carbon fiber precursor phase is used in wet spinning caused by the storm.