page_title: Intercalation (chemistry)
section_title: Graphite
hierarchical_section_title: Intercalation (chemistry) / Examples / Graphite
caption_attribution_description: English: cartoon for intercalation of Li into TiS2 cathode Deutsch: Schema der de:Interkalation von Lithiumionen in eine Titandisulfidkathode und Umkehrung (Deinterkalation) des Vorgangs. Beim Entladen (discharge) einer entsprechenden Batterie wird das Titan vom vierwertigen zum dreiwertigen Oxidationszustand reduziert, beim Laden (discharge) wird das Titan oxidiert.
context_page_description: In chemistry, intercalation is the reversible inclusion or insertion of a molecule into materials with layered structures. Examples are found in graphite and transition metal dichalcogenides.
context_section_description: One famous intercalation host is graphite, which intercalates potassium as a guest. Intercalation expands the van der Waals gap between sheets, which requires energy. Usually this energy is supplied by charge transfer between the guest and the host solid, i.e., redox. Two potassium graphite compounds are KC₈ and KC₂₄. Carbon fluorides (e.g., (CF)ₓ and (C₄F)) are prepared by reaction of fluorine with graphitic carbon. The color is greyish, white, or yellow. The bond between the carbon and fluorine atoms is covalent, thus fluorine is not intercalated. Such materials have been considered as a cathode in various lithium batteries.
  Treating graphite with strong acids in the presence of oxidizing agents causes the graphite to oxidise. Graphite bisulfate, [C₂₄]⁺[HSO₄]⁻, is prepared by this approach using sulfuric acid and a little nitric acid or chromic acid. The analogous graphite perchlorate can be made similarly by reaction with perchloric acid.
caption: Diagram of intercalation of Li into a titanium disulfide cathode. One axis of the TiS2 crystal swells, and charge transfers from Li to Ti.
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