Cathode material for lithium secondary battery and method for producing lithiated nickel dioxide and lithium secondary battery

• US 5,824,284 A
• Filed: 03/28/1997
• Issued: 10/20/1998
• Est. Priority Date: 07/15/1993
• Status: Expired due to Term

• Current Assignee: Sumitomo Chemical Company Limited
• Original Assignee: Sumitomo Chemical Company Limited
• Inventors: Satoh, Tomoari, Nakane, Kenji, Nishida, Yasunori
• Primary Examiner(s): BOS, STEVEN J
• Application Number:
  US08/827,497
• Time in Patent Office: 571 Days
• Field of Search: 423/594, 429/223
• US Class Current: 423/594.4
• CPC Class Codes: C01G 53/42 containing alkali metals, e.g. LiNiO2
• CPC Class Codes: C01P 2002/30 Three-dimensional structures
• CPC Class Codes: C01P 2002/52 containing elements as dopants
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C01P 2006/40 Electric properties
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 4/525 of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

The invention provides a cathode material for lithium secondary battery containing lithiated nickel dioxide having excellent charge/discharge characteristics and a process for producing the lithiated nickel dioxide, and a lithium secondary battery. That is, the cathode material for lithium secondary battery contains lithiated nickel dioxide having α-NaFeO₂ structure and shows a coulomb efficiency of 80% or higher at the first charging and discharging, and the process for producing lithiated nickel dioxide comprises dispersing a nickel compound in a lithium nitrate solution, then evaporating the solvent to obtain a mixture of lithium nitrate and the nickel compound and firing the mixture in an atmosphere containing oxygen.

Claims

1. A process for producing lithiated nickel dioxide for use in a cathode of a lithium secondary battery, the lithiated nickel dioxide having an α

-NaFeO₂ structure, the lithiated nickel dioxide having a coulomb efficiency of 80% or higher at the first charging and discharging of the lithiated nickel dioxide in the cathode of a lithium secondary battery, comprising the steps of dispersing a nickel compound in a solvent-containing lithium nitrate solution, the nickel compound being insoluble in the solvent-containing lithium nitrate solution, then evaporating the solvent to obtain a mixture of lithium nitrate and the nickel compound and firing the mixture in an atmosphere containing oxygen.

2. A process according to claim 1 wherein the solvent-containing lithium nitrate solution contains a solvent selected from the group consisting of water, an alcohol and mixtures thereof.

3. A process according to claim 2 wherein the solvent for the solvent-containing lithium nitrate solution is water.

4. A process according to claim 1 wherein the nickel compound has an average particle size of 100 μ

m or smaller.

5. A process according to claim 6 wherein the nickel compound has an average particle size of 50 μ

m or smaller.

6. A process according to claim 1 wherein the nickel compound has a specific surface area of 1 m² /g or larger.

7. A process according to claim 1 wherein when the nickel compound is dispersed in the solvent-containing lithium nitrate solution, the nickel compound is charged in a vacuum container, the container is evacuated and then the solvent-containing lithium nitrate solution is added to the nickel compound to vacuum impregnate the nickel compound with the solvent-containing lithium nitrate solution.

8. A process according to claim 1 wherein the mixing ratio of lithium nitrate and the nickel compound is in the range of 1.0≦

Li/Ni≦

1.1.

9. A process according to claim 1 wherein the firing atmosphere is oxygen.

10. A process according to claim 9 wherein the firing is carried out in an oxygen stream.

11. A process according to claim 1 wherein a mixed powder of lithium nitrate and the nickel compound is dried at a temperature lower than the melting point of lithium nitrate before firing.

12. A process according to claim 1 wherein the firing is carried out at 350°

-800°

C.

13. A process according to claim 12 wherein the firing is carried out at 600°

-750°

C.

14. A process for producing lithiated nickel dioxide, comprising the steps of dispersing a nickel compound in a solvent-containing lithium nitrate solution, the nickel compound being insoluble in the solvent-containing lithium nitrate solution, evaporating the solvent to obtain a mixture of lithium nitrate and the nickel compound, firing the mixture in an atmosphere containing oxygen, and obtaining lithiated nickel dioxide having a α

-NaFeO₂ structure, such that the lithiated nickel dioxide obtained has the property of a first charging and discharging coulomb efficiency of 80% or higher when used as a cathode of a lithium secondary battery.

15. A process according to claim 14, wherein the property of a first charging and discharging coulomb efficiency is 85% or higher.