Graphite, intercalation compounds with bromine

Alkali metals and bromine react with graphite to form solids known as intercalation compounds, where the foreign atoms are inserted between the intact graphite layers. Many other layered solids, for example dichalcogenides such as TaS2, which have structures similar to Cdl2 will also for intercalation compounds. The inserted species may be alkali metals, or electron donor molecules such as amines or organometallic compounds. 

The residual intercalant is retained at crystal imperfections such as crystallite boundaries or twin lines and x-ray diffraction may show graphite reflections only. Residue compounds with large interplanar distances have residual intercalant between the carbon planes . In bromine residue compounds ordered layers of intercalant are found by electron diffraction . Thus there is no distinct borderline between dilute lamellar and residue compounds. 

Intercalation compounds Alkali metals react with graphite in such a way that they get between the layers of graphite and cause the layers to expand. Intercalation compounds are commonly composed of the alkali metals, bromine, or some electron donor molecules such as amines or organometallic compounds. This is found in lithium ion batteries, for example. 

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