GRAPHITE POWDERS SUITED FOR NEGATIVE ELECTRODE MATERIAL OF LITHIUM ION SECONDARY BATTERY

• US 20010051300A1
• Filed: 04/16/1999
• Published: 12/13/2001
• Est. Priority Date: 04/21/1998
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: MORIGUCHI, KOJI, ABE, MASARU, KAMINAKA, HIDEYA, KAMEI, KAZUHITO, NEGI, NORIYUKI, YONEMURA, MITSUHARA, OMARU, ATSUO, NAGAMINE, MASAYUKI
• Granted Patent: US 6,764,767 B2
• Time in Patent Office: Days
• US Class Current: 429/231.8
• CPC Class Codes: C01B 32/20 Graphite
• CPC Class Codes: C01B 32/205 Preparation
• CPC Class Codes: C01B 32/21 After-treatment
• CPC Class Codes: C01P 2002/60 Compounds characterised by their crystallite size
• CPC Class Codes: C01P 2002/72 by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: C01P 2006/80 Compositional purity
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 2004/021 Physical characteristics, e.g. porosity, surface area
• CPC Class Codes: H01M 4/133 Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: H01M 4/587 for inserting or intercalating light metals
• CPC Class Codes: Y10T 428/30 Self-sustaining carbon mass or layer with impregnant or other layer

Abstract

A graphite powder suitable for a negative electrode material of a lithium ion secondary battery which assures a high discharging capacity not lower than 320 mAh/g is to be manufactured at a lower cost. Specifically, a graphite powder containing 0.01 to 5.0 wt % of boron and having a looped closure structure at an end of a graphite c-planar layer on the surface of a powder, with the density of the interstitial planar sections between neighboring closure structures being not less than 100/μm and not more than 1500/μm, and with d002 being preferably not larger than 3.3650 Å, is manufactured by (1) heat-treating a carbon material pulverized at an elevated speed before or after carbonization for graphization at temperature exceeding 1500° C. or by (2) heat-treating the carbon material pulverized before or after carbonization at a temperature exceeding 1500° C. for graphization and subsequently further heat-treating the graphized material at a temperature exceeding a temperature of the oxidating heat treatment and the heat treatment in the inert gas.

Claims

1. A graphite powder containing 0.01 to 5.0 wt % of boron and having a looped closure structure at an end of a graphite c-planar layer on the surface of a powder, with the density of the interstitial planar sections between neighboring closure structures being not less than 100/μ

m and not more than 1500/μ

m.

2. The graphite powder according to

claim 1

wherein the distance between c-axis (002) planar lattice distance (d002) as found by the lattice constant precision method by X-ray diffraction is not more than 3.3650 Å

.

3. The graphite powder according to

claim 1

or

2

wherein the specific surface area is not more than 1.0 m²/g, the crystallite diameter is 100 to 2000 Å

and/or the volume cumulative mean particle size as measured by the laser diffraction scattering method is 5 to 35 μ

m.

4. A method for producing a graphite powder according to any one of claims 1 to 3 comprising:

a step of adding boron;

wherein

a carbon material pulverized at an elevated speed before and/or after carbonization is heat-treated at a temperature exceeding 1500°

C. for graphization.

5. A method for producing a graphite powder according to any one of

claims 1

to

3

comprising:

a step of adding boron;

wherein

a carbon material pulverized before and/or after carbonization is heat-treated at a temperature exceeding 1500°

C. for graphization,

the heat-treated carbon material is surface-processed under a condition of scraping the surface of the produced graphite powder; and

wherein

the surface-processed carbon material is heat-treated in an inert gas at a temperature exceeding 800°

C.

6. The method for producing a graphite powder according to

claim 5

wherein

the heat treatment under the condition of scraping the surface of the produced graphite powder is oxidating heat treatment.

7. The method for producing a graphite powder according to any one of

claims 4

to

6

wherein the carbon material is obtained by carbonization of mesophase globules and/or the bulk mesophase.

8. A negative electrode material of a lithium ion secondary battery mainly composed of graphite powders according to any one of

claims 1

to

3

.

9. A lithium ion secondary battery including a negative electrode manufactured from a negative electrode material according to

claim 8

.