Meaning
Structural transformation of carbon materials into a highly ordered hexagonal lattice occurs at temperatures exceeding two thousand degrees Celsius. Through graphitization, the random orientation of atoms in a precursor like petroleum coke becomes a series of parallel layers. This change increases the density of the material.
The resulting product is essential for efficient lithium ion intercalation.
Thermal Energy
Extreme heat is the primary driver for moving carbon atoms into their most stable energy state. Inside the thermal energy of graphitization, the duration of the soak period at peak temperature determines the degree of crystallinity achieved. Induction furnaces or Acheson kilns provide the necessary environment.
Energy consumption is a major factor in the final cost of the anode material.
Lattice Ordering
Interlayer spacing between the carbon sheets narrows as the structure matures. The lattice ordering of graphitization is measured by X ray diffraction to confirm that the d002 value is approaching the theoretical ideal of three point three five angstroms. Better ordering leads to higher capacity.
This allows for more lithium ions to reside between the layers.
Conductivity Gain
Metallic properties emerge as the electrons find easier paths along the basal planes. The conductivity gain of graphitization results in a massive drop in electrical resistance. Thermal conductivity also rises.
This allows the battery to stay cooler during high power operations.
