Electrode structures and surfaces for Li batteries
This invention relates to methods of preparing positive electrode materials for electrochemical cells and batteries. It relates, in particular, to a method for fabricating lithium-metal-oxide electrode materials for lithium cells and batteries. The method comprises contacting a hydrogen-lithium-manganese-oxide material with one or more metal ions, preferably in an acidic solution, to insert the one or more metal ions into the hydrogen-lithium-manganese-oxide material; heat-treating the resulting product to form a powdered metal oxide composition; and forming an electrode from the powdered metal oxide composition.
1. A method of preparing a positive electrode for an electrochemical cell, the method comprising the steps of:
(a) contacting a precursor compound comprising lithium and manganese metal ions with an aqueous acidic solution containing one or more other metal ions to form a hydrogen-lithium-manganese-oxide and concurrently to insert the one or more other metal ions into the hydrogen-lithium-manganese-oxide to form an oxide intermediate therefrom;
(b) heating the oxide intermediate from step (a) at a temperature in the range of about 300 to about 1000° C. to form a powdered metal oxide product; and
(c) forming an electrode from the powdered metal oxide product;
wherein the powdered metal oxide product has an integrated structure comprising a combination of two or more crystal structures selected from a layered crystal structure, a spinel crystal structure, and a rocksalt crystal structure, and wherein the precursor compound comprises lithium, manganese, and oxygen ions in a layered-type structure wherein lithium ions occupy octahedral sites in lithium-containing layers, and the lithium and manganese ions occupy octahedral sites in manganese-containing layers that alternate with the lithium-containing layers; and wherein the metal ions in the acidic solution consist of one or more metal ions are selected from the group consisting of an alkali metal ion, an alkaline earth metal ion, a transition metal ion, and an aluminum ion.
2. The method of claim 1 wherein the precursor compound comprises Li 2 MnO 3 or Li[Li 1/3 Mn 2/3 ]O 2 , and optionally includes up to 25 atom percent of one or more metal ions other than Li and Mn.
3. The method of claim 2 wherein the one or more metal ions other than Li and Mn comprises a Ti ion, a Zr ion, a Co ion, a Ni ion, or a combination thereof.
4. The method of claim 1 wherein the aqueous acidic solution also includes one or more metalloid-containing ions, non-metal containing ions, or a combination thereof.
5. The method of claim 1 wherein the one or more other metal ions in the aqueous acidic solution comprises at least one alkali metal ion selected from the group consisting of a Li ion, a Na ion and a K ion.
6. The method of claim 1 wherein the one or more other metal ions in the aqueous acidic solution comprises at least one alkaline earth metal ion selected from the group consisting of a Mg ion and a Ca ion.
7. The method of claim 1 wherein the one or more other metal ions in the aqueous acidic solution comprises at least one transition metal ion selected from the group consisting of a Ti ion, a V ion, a Mn ion, a Fe ion, a Co ion, a Ni ion, a Zr ion, and a Mo ion.
8. The method of claim 1 wherein the electrode contains cation or anion defects and/or stacking faults and dislocations.
9. The method of claim 1 wherein the precursor compound is prepared by the reaction of one or more lithium salts, one or more manganese salts, and optionally one or more other metal salts at a temperature in the range of about 450 to about 550° C. in air.
10. The method of claim 9 wherein the lithium salts, manganese salts and other metal salts are selected from the group consisting of carbonates, hydroxides, nitrates, and isopropoxides.
11. The method of claim 1 wherein the heating in step (b) is at a temperature in the range of about 400 to about 950° C.
12. The method of claim 1 wherein the hydrogen-lithium-manganese-oxide material comprises hydrogen, lithium, manganese, and oxygen ions, and the oxygen ions are arranged in alternating layers of octahedra and trigonal prisms in the crystal structure of the material.
13. The method of claim 1 further comprising applying to a surface of the electrode, the individual particles of the powdered metal oxide composition, or both, a coating of at least one material selected from the group consisting of a metal oxide, a metal fluoride, and a metal polyanionic material.
14. The method of claim 13 wherein the coating comprises at least one material selected from the group consisting of (a) lithium fluoride, (b) aluminum fluoride, (c) a lithium-metal-oxide in which the metal is selected from the group consisting of Al and Zr, (d) a lithium-metal-phosphate in which the metal is selected from the group consisting of Fe, Mn, Co, and Ni, and (e) a lithium-metal-silicate comprising a metal selected from the group comprising Al and Zr.
15. The method of claim 1 wherein the hydrogen-lithium-manganese-oxide material, prior to treatment with the acidic solution, also includes up to 25 atom percent of one or more other transition metal ions replacing manganese ions, lithium ions, or a combination thereof in a manganese-containing layer of the material.
16. The method of claim 15 wherein the one or more other transition metal ions comprises a Ti ion, a Zr ion, a Co ion, a Ni ion, or a combination thereof.