Fluorinated Graphite Thermal Stability Assessed via TGA and XRD Testing

Properties of Fluorinated Graphite

Physical Properties

C/F Atomic Ratio

The performance of fluorinated graphene varies with the ratio of C/F atoms in its molecular structure. A C/F ratio ≤ 1 is referred to as high fluorination degree fluorinated graphene; a C/F ratio > 1 is referred to as low fluorination degree fluorinated graphene.

High Fluorination DegreeGraphite boasts excellent thermal stability, serves as an insulator for electricity and heat, and is resistant to corrosion from strong acids and alkalis. Its lubricating properties exceed those of MoS.₂And Flake Graphite.

Low Fluoride ContentGraphite is gray-black in color, with poor thermal stability and is generally not used as a lubricant. However, it is an ideal material for manufacturing high-energy, anode-free batteries. The electrochemical capacity of carbon fluoride as the cathode material in lithium carbon fluoride batteries primarily depends on the carbon-fluorine ratio, pore structure, material conductivity, voltage platform, and discharge capacity, which are the main factors determining energy density. Lithium ions react with the fluorine on the carbon fluoride surface, causing the carbon-fluorine bond to transition from sp3 to sp2 hybridization. As the discharge reaction progresses, the electrical conductivity of the cathode material will increase to some extent.

2. Thermal Stability

Only slight weight loss occurs above 500°C, indicating poor thermal stability for the compound.

3. Lubricity Performance

It boasts the lowest coefficient of friction among lubricating greases and solid lubricants, such as molybdenum disulfide and graphite, with a coefficient of friction ranging from 0.1 to 0.13 within the temperature range of 27~344°C.

Chemical Properties

Surface Energy: The surface energy of fluoro-graphite is extremely low.

Section 3: XRD Characterization

XRD test results show that the degree of fluorination is very uniform among the four different carbon sources and fluorocarbon ratios depicted in the image. The fluorine gas reaction inserts into the layers from the edge, while the flake graphite takes much longer. At a fluorocarbon ratio of 0.51, the fluorination is not complete, and there is still a strong peak of the graphite structure.