Topochemical intercalation of high molar mass species is well known for many layered hosts, but has not been previously described for graphite. This technology uses the strong affinity of oligo- or poly-ethers for alkali metal cations to form cationic species that can diffuse into graphite to form layered nanocomposites. The resulting materials are stack-ordered and contain single reduced graphene sheets with the cationic polymer-alkali metal cation complex incorporated between the sheets. Other graphite intercalation reactions have been shown to be highly reversible for sodation when co-intercalates are present, however, these materials uptake and lose the co-intercalates. The resulting volume changes may prevent practical applications as reversible electrodes. When high molar mass co-intercalates are introduced, this uptake and loss and the associated volume changes may be avoided.
Features & Benefits
Background of Invention
Nanocomposites containing graphite or graphene sheets are of interest for electrochemical applications, such as an anode in reversible charge-storage devices or in supercacitors. Layered host-polymer nanocomposites comprising an ordered nanoscale combination of layered host sheets with polymeric guest galleries have been prepared with many different inorganic hosts, but no such materials have previously been obtained from graphite. This invention provides, for the first time, topo-chemical methods to obtain ordered nanocomposites comprising an oligo- or poly-ether and single graphene sheets. The incorporation of a high molar mass co-intercalate between graphene sheets will enable reversible sodiation of the material and improve cell cycle life, a property that can be exploited in preparing new reversible electrodes for energy storage.
Patent pending and available for license.