Lithium manganate, method of producing the same, and lithium cell produced by the method

• US 6,334,993 B1
• Filed: 08/16/1999
• Issued: 01/01/2002
• Est. Priority Date: 12/22/1997
• Status: Expired due to Term

• Current Assignee: Ishihara Sangyo Kaisha Limited
• Original Assignee: Ishihara Sangyo Kaisha Limited
• Inventors: Miyazaki, Hiromitsu, Suita, Tokuo
• Primary Examiner(s): BOS, STEVEN J
• Application Number:
  US09/367,285
• Time in Patent Office: 869 Days
• Field of Search: 423/599, 429/224
• US Class Current: 423/599
• CPC Class Codes: C01G 45/02 Oxides; Hydroxides
• CPC Class Codes: C01G 45/1221 Manganates or manganites with a manganese oxidation state of Mn(III), Mn(IV) or mixtures thereof
• CPC Class Codes: C01G 45/1242 of the type [Mn2O4]-, e.g. LiMn2O4, Li[MxMn2-x]O4
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C01P 2004/62 Submicrometer sized, i.e. from 0.1-1 micrometer
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C01P 2006/14 Pore volume
• CPC Class Codes: C01P 2006/40 Electric properties
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 2004/021 Physical characteristics, e.g. porosity, surface area
• CPC Class Codes: H01M 4/02 Electrodes composed of, or comprising, active material
• CPC Class Codes: H01M 4/0471 involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
• CPC Class Codes: H01M 4/505 of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

The present invention relates to a lithium manganate useful as an active material of positive electrodes for lithium batteries, and a process for producing the same, a positive electrode which uses the same as an active material of positive electrode, and a lithium battery. The lithium manganate of the present invention has a cubic particle form and contains voids in the particles, and therefore lithium batteries using it as an active material of positive electrodes provides a high initial discharge capacity of at least 95 mAh/g and, besides, are excellent in cycle characteristics.

Claims

1. A process for producing a lithium manganate which includes a step of reacting a manganese compound with an alkali to obtain a manganese hydroxide, a step of oxidizing the manganese hydroxide in an aqueous medium or a gaseous phase to obtain a manganese oxide, a step of reacting the manganese oxide with a lithium compound in an aqueous medium to obtain a lithium manganate precursor, and a step of firing the precursor to obtain a lithium manganate.

2. A process according to claim 1, wherein the manganese oxide and the lithium compound are subjected to hydro-thermal treatment in an aqueous medium in the step of reacting the manganese oxide with a lithium compound in an aqueous medium to obtain a lithium manganate precursor.

3. A process according to claim 1, wherein an oxidizing agent is fed into a reactor in batch-wise or continuous manner in the step of reacting the manganese oxide with a lithium compound in an aqueous medium to obtain a lithium manganate precursor.

4. A process according to claim 1 wherein the reaction of manganese oxide with a lithium compound in an aqueous medium to obtain a lithium manganate precursor occurs at a temperature of 50°

C. or higher.

7. A process according to claim 1 or 5, wherein the manganese compound is a water-soluble manganese compound.

9. A process according to claim 1 or 5, wherein the lithium compound is lithium hydroxide.

13. A process according to claim 1 or claim 5, wherein the produced lithium manganate is employed in the production of a positive electrode.

14. A process according to claim 1 or claim 5, wherein the produced lithium manganate is employed in the production of a lithium battery.

5. A process for producing a lithium manganate which includes a step of reacting a manganese compound with an alkali to obtain a manganese hydroxide, a step of oxidizing the manganese hydroxide in an aqueous medium or a gaseous phase to obtain a manganese oxide, a step of reacting the manganese oxide with an acid in an aqueous medium to obtain a proton-substituted manganese oxide, a step of reacting the proton-substituted manganese oxide with a lithium compound in an aqueous medium to obtain a lithium manganate precursor, and a step of firing the precursor to obtain a lithium manganate.

6. A process according to claim 5, wherein the acid is at least one acid selected from hydrochloric acid, sulfuric acid, nitric acid and hydrofluoric acid.

8. A process according to claim 5, wherein the manganese oxide or the proton-substituted manganese oxide and the lithium compound are subjected to hydro-thermal treatment in an aqueous medium in the step of reacting the proton-substituted manganese oxide with a lithium compound in an aqueous medium to obtain a lithium manganate precursor.

10. A process according to claim 5, wherein an oxidizing agent is fed into a reactor in batch-wise or continuous manner in the step of reacting the proton-substituted manganese oxide with a lithium compound in an aqueous medium to obtain a lithium manganate precursor.

11. A process according to claim 10, wherein the oxidizing agent is at least one agent selected from air, oxygen, ozone, aqueous hydrogen peroxide and peroxodisulfate.

12. A process according to claim 5 wherein the reaction of the proton-substituted manganese oxide with a lithium compound in an aqueous medium to obtain a lithium manganate precursor occurs at a temperature of 50°

C. or higher.