Positive electrode active material for lithium secondary battery and process for producing the same

Inactive Publication Date: 2006-11-23
SEIMI CHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0010] It is an object of the present invention to provide a positive electrode active material for a lithium secondary battery, which has a large volume capacity density and

Problems solved by technology

On the other hand, there has been a problem of deterioration of the cyclic properties such as gradual reduction of the battery discharge capacity due to repetitive charge and discharge cycle, a problem of the weight capacity density or substantial reduction of the discharge capacity at a low temperature.
With such a positive electrode active material, the coating properties and the cyclic properties have been improved, but, the safety, the volume capacity density and the weight capacity density, have not yet been fully satisfactory.
In such a proposal, there may be a case where the weight capacity density and the charge and discharge cyclic properties of the positive electrode can

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Example

EXAMPLE 1

[0062] A spherical cobalt hydroxide powder formed by agglomeration of primary particles having, in powder X-ray diffraction using CuKα-ray, a half value width of the diffraction peak on (001) plane at 2θ=19±1° of 0.28° and a half value width of the diffraction peak on (101) plane at 2θ=38±1° of 0.21°, average particle sizes D50 of 16.7 μm, D10 of 13.4 μm and D90 of 21.1 μm, and a specific surface area of 3.6 m2 / g, and a lithium carbonate powder having a specific surface area of 1.2 m2 / g, were mixed. They were blended in such a mixture ratio that the composition would be LiCoO2 after firing. After dry mixing of these two types of powders, the mixture was fired in the air atmosphere at 950° C. for 12 hours.

[0063] The fired product was crushed, and the particle size distribution of the obtained large particle size LiCoO2 powder formed by agglomeration of primary particles was measured by using a laser scattering type particle size distribution measuring apparatus and as a re...

Example

EXAMPLE 2

[0070] A mixed powder was obtained in the same manner as in Example 1 except that 80 parts by weight of the powder A and 20 parts by weight of the powder B were mixed. The mixed powder after pressing had an apparent density of 3.23 g / cm3. Further, by using this powder, in the same manner as in Example 1, a positive electrode was produced, batteries were assembled, and the properties were measured. The weight capacity density was 160 mAh / g, the capacity retention ratio after 30 times of charge and discharge cycle was 97.5%, and the heat generation starting temperature was 163° C.

Example

EXAMPLE 3

[0071] A mixed powder was obtained in the same manner as in Example 1 except that 40 parts by weight of the powder A and 60 parts by weight of the powder B were mixed. The mixed powder after pressing had an apparent density of 3.13 g / cm3. Further, by using this powder, in the same manner as in Example 1, a positive electrode was produced, batteries were assembled, and the properties were measured. The weight capacity density was 160 mAh / g, the capacity retention ratio after 30 times of charge and discharge cycle was 97.2%, and the heat generation starting temperature was 163° C.

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Abstract

A positive electrode active material for a lithium secondary battery containing a lithium-cobalt composite oxide, which has a large volume capacity density, has a high safety and is excellent in charge and discharge cyclic durability, and its production process, are provided.
A lithium-cobalt composite oxide represented by the formula LipCoxMyOzFa (wherein M is a transition metal element other than Co or an alkaline earth metal element, 0.9≦p≦1.1, 0.980≦x≦1.000, 0≦y≦0.02, 1.9≦z≦2.1, x+y=1 and 0≦a≦0.02) and comprising a mixture containing substantially spherical hard first particles of lithium-cobalt composite oxide having such a sharp particle size distribution that the volume basis cumulative size D10 is at least 50% of the average particle size D50, and the volume basis cumulative size D90 is at most 150% of the average particle size D50, and second particles of lithium-cobalt composite oxide filling the space among the first particles, in a mass ratio of first particles/second particles of from 1/2 to 9/1, and process for producing the same.

Description

TECHNICAL FIELD [0001] The present invention relates to a positive electrode active material for a lithium secondary battery, which has a large volume capacity density and high safety and is excellent in the charge and discharge cyclic durability, a positive electrode for a lithium secondary battery employing it, and a lithium secondary battery. BACKGROUND ART [0002] Recently, as the portability and cordless tendency of instruments have progressed, a demand for a non-aqueous electrolyte secondary battery such as a lithium secondary battery which is small in size and light in weight and has a high energy density, has been increasingly high. As a positive electrode active material for the non-aqueous electrolyte secondary battery, a composite oxide of lithium and a transition metal such as LiCoO2, LiNiO2, LiNi0.8Co0.2O2, LiMn2O4 or LiMnO2, has been known. [0003] Among them, a lithium secondary battery using a lithium-cobalt composite oxide (LiCoO2) as a positive electrode active mater...

Claims

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Application Information

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IPC IPC(8): H01M4/58H01M4/52C01G51/00H01M4/131H01M4/1315H01M4/48H01M4/485H01M4/525H01M10/052H01M10/0565H01M10/36
CPCC01G51/006Y02E60/122C01P2002/52C01P2002/72C01P2002/74C01P2004/03C01P2004/32C01P2004/45C01P2004/51C01P2004/54C01P2006/11C01P2006/12C01P2006/40H01M4/131H01M4/1315H01M4/485H01M4/525H01M10/052H01M10/0565H01M2004/021C01G51/42Y02E60/10H01M4/04H01M10/0525
Inventor SUHARA, MANABUSAITO, NAOSHIHORICHI, KAZUSHIGEUCHIDA, MEGUMI
Owner SEIMI CHEM CO LTD
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