Intercalation process explanation

[Stanley514]

Could somebody explain in detail, how intercalation process works?
For exampe, when Li ion intercalates in graphite where goes external (valent)
electron of Li atom? Does it become common with graphite atoms?
Is this true that smaller ions easier intercalate into substrate?
What`s about protons, which have very small size?Is there some substances
which allow to intercalate protons easy?
Is this true that Silicon could intercalate more then three Li ions per it`s own
atom? How is it possible?

 

[jbsteele]

Intercalation is a process in which molecules or ions are inserted between the layers of a solid material. The process involves inserting an atom or ion between the layers of the solid material, and this often results in a modification of its physical and chemical properties. For example, when lithium ion intercalates in graphite, the lithium ion occupies a space between the layers of graphite atoms and forms strong bonds with them. The external electron of the lithium atom becomes shared between the lithium ion and the graphite atoms, forming a covalent bond. In general, smaller ions are easier to intercalate than larger ones because they can more easily fit into the available space between the layers. However, even though protons are very small, they cannot be intercalated into most substances due to their high charge and reactivity. Instead, special materials known as proton exchange membranes (PEMs) are used to facilitate proton intercalation. Finally, it is true that silicon can intercalate more than three lithium ions per atom. This is possible because silicon has a higher electronegativity than lithium, which allows it to form stronger bonds with the lithium ions. Thus, silicon can accommodate more lithium ions than other materials.