1. Chemical intercalation method: the initial raw material for preparation is high carbon flake graphite, and other chemical reagents such as concentrated sulfuric acid (more than 98%), hydrogen peroxide (more than 28%), Potassium permanganate, etc. use industrial grade reagents. The general steps for preparation are as follows: under appropriate temperature, hydrogen peroxide solution with different ratios, natural flake graphite and concentrated sulfuric acid are added in different procedures, and reacted for a certain time under constant agitation, and then washed with water to neutral, Centrifuge separation, dehydrate and vacuum dry at 60 ℃.

2. Electrochemical method: Treating graphite powder in a strong acid electrolyte to produce expandable graphite, hydrolyzing, cleaning, and drying. As a strong acid, sulfuric acid or nitric acid is mainly used. This method produces expandable graphite with low sulfur content.

3. Ultrasonic oxidation method: In the process of preparing expandable graphite, the electrolyte of anodic oxidation is subjected to ultrasonic vibration, and the time of ultrasonic vibration is the same as that of anodic oxidation. As the vibration of the electrolyte by ultrasonic is conducive to the polarization of the cathode and anode, it accelerates the rate of anode oxidation and shortens the oxidation time.

4. Gas phase diffusion method: The graphite and intercalation material are placed at both ends of a vacuum sealed tube, heated at the end of the intercalation material, and the necessary reaction pressure difference is formed by utilizing the temperature difference between the two ends, allowing the intercalation material to enter the interlayer of flake graphite in a small molecule state, thus producing expandable graphite. The number of layers produced by this method can be controlled, but its production cost is high.

5. Molten salt method: Mix and heat several inserts with graphite to form expandable graphite.