Layered materials with improved magnesium intercalation for rechargeable magnesium ion cells
Electrochemical devices which incorporate cathode materials that include layered crystalline compounds for which a structural modification has been achieved which increases the diffusion rate of multi-valent ions into and out of the cathode materials. Examples in which the layer spacing of the layered electrode materials is modified to have a specific spacing range such that the spacing is optimal for diffusion of magnesium ions are presented. An electrochemical cell comprised of a positive intercalation electrode, a negative metal electrode, and a separator impregnated with a nonaqeuous electrolyte solution containing multi-valent ions and arranged between the positive electrode and the negative electrode active material is described.
1. A multivalent-ion battery containing an electrode produced by a method comprising the steps of:
forming an inorganic material having a layered structure; and
exposing said inorganic material to an organic substance so that said organic substance becomes inserted into said layered structure of said inorganic material, said organic substance causing a modification of said layered structure of said inorganic material in which a first plurality of layers of said inorganic material are separated by a second plurality of units of said organic substance situated on intervening planes so as to allow efficient intercalation of a multivalent ionic species.
2. The multivalent-ion battery of claim 1 , wherein said multivalent ion is magnesium.
3. The multivalent-ion battery of claim 1 , wherein said organic substance is an organic molecule.
4. The multivalent-ion battery of claim 1 , wherein said organic substance is an onium ion.
5. The multivalent-ion battery of claim 4 , wherein said onium ion is a tetra-alkyl-ammonium ion.
6. The multivalent-ion battery of claim 4 , wherein said onium ion is a tetra-alkyl-phosphonium ion.
7. The multivalent-ion battery of claim 4 , wherein said onium ion is di-alkyl-pyrrolidinium ion.
8. The multivalent-ion battery of claim 4 , wherein said onium ion is di-alkyl-imidazolium ion.
9. The multivalent-ion battery of claim 4 , wherein said onium ion is di-alkyl-piperidinium ion.
10. The multivalent-ion battery of claim 1 , wherein said inorganic material having a layered structure is a layered metal oxide compound.
11. The multivalent-ion battery of claim 1 , wherein said inorganic material having a layered structure has the chemical formula Mg a M b X y , wherein M is a metal cation or a mixture of metal cations, X is an anion or mixture of anions, a is in the range of 0 to about 2, b is in the range of about 1 to about 2, and y≦9.
12. The multivalent-ion battery of claim 11 , wherein M is Mo or a mixture of metal cations including Mo, and X is O.
13. The multivalent-ion battery of claim 11 , wherein M is V and Li or a mixture of metal cations including V and Li, and X is O.
14. The multivalent-ion battery of claim 11 , wherein M is V or a mixture of metal cations including V, and X is O(PO 4 ).
15. The multivalent-ion battery of claim 11 , wherein M is V or a mixture of metal cations including V, and X is O, F, or a mixture thereof.
16. The multivalent-ion battery of claim 11 , wherein M is Mn or a mixture of metal cations including Mn, and X is O.
17. The multivalent-ion battery of claim 11 , wherein M is Co or a mixture of metal cations including Co, and X is O.
18. The multivalent-ion battery of claim 11 , wherein M is Ni or a mixture of metal cations including Ni, and X is O.
19. The multivalent-ion battery of claim 11 , wherein M is Ni and H or a mixture of cations including Ni and H, and X is O.
20. The multivalent-ion battery of claim 1 , wherein said exposing step involves an electrochemical step.
21. The multivalent-ion battery of claim 1 , wherein said exposing step involves a chemical reaction.