Properties of graphite

Graphite is the most common negative electrode material in commercial LIBs. It is widely used in batteries because it exhibits unique properties. Highly purified graphite acts as the negative electrode material into which lithium ions are intercalated.

Graphite is exceptionally soft, with a Mohs hardness of 1–2. It has a theoretical density of (2.26 hspace{0.1 cm} g hspace{0.1 cm} cm^{-3}). Graphite is used in many industrial applications because it exhibits both metallic properties (thermal and electrical conductivity) and non-metallic properties (inert, high thermal resistance and lubricity).

Graphitic materials are excellent anode materials because they exhibit an ordered layered crystalline structure, highly reversible lithium storage capacity, low charge-discharge potential, excellent electrical conductivity, and broad potential plateau. Low working potentials ((approx 0.15 V hspace{0.1 cm} vs. hspace{0.1 cm} Li^{+}/Li)) and high theoretical capacities ((372 hspace{0.1 cm} mAh hspace{0.1 cm} g^{-1})) of graphite make them the most commonly used anode materials in LIBs.

Graphitic materials are also quite cost-effective, safe when not contaminated, and chemically stable in a wide range of temperatures. Graphite is mainly used in refractories, used as expandable graphite, applied in brake linings, and used in steelmaking-foundry operations. Graphite anodes exhibit a limited theoretical capacity of (372 hspace{0.1 cm} mAh hspace{0.1 cm} g^{-1}) in their fully lithiated state.

Other key properties of graphite are as follows:

• high electrical conductivity
• high thermal conductivity
• stability (chemically and thermally resistant)
• environmentally friendly (non-toxic)
• ease of manufacturing
• low redox potential and high specific charge.