Lithium-ion secondary battery

Patent metadata

Field	Value
Publication number	US-9972844-B2
Application number	US-201114349437-A
Country	US
Kind code	B2
Filing date	Oct 7, 2011
Priority date	Oct 7, 2011
Publication date	May 15, 2018
Grant date	May 15, 2018

Abstract

A negative electrode active material layer ( 243 A) of a lithium-ion secondary battery ( 100 A) contains natural graphite and artificial graphite as negative electrode active material particles. The negative electrode active material layer ( 243 A) has a region (A 1 ) facing the positive electrode active material layer ( 223 ) and regions (A 2 , A 3 ) not facing the positive electrode active material layer ( 223 ). The region (A 1 ) facing the positive electrode active material layer ( 223 ) contains the natural graphite in a larger proportion than the regions (A 2 , A 3 ) not facing the positive electrode active material layer ( 223 ), and the regions (A 2 , A 3 ) not facing the positive electrode active material layer ( 223 ) contain the artificial graphite in a larger proportion than the region (A 1 ) facing the positive electrode active material layer ( 223 ).

First claim

The invention claimed is:

1. A lithium-ion secondary battery comprising:
a positive electrode current collector;
a positive electrode active material layer retained on the positive electrode current collector;
a negative electrode current collector; and
a negative electrode active material layer retained on the negative electrode current collector and disposed so as to cover the positive electrode active material layer,
the negative electrode active material layer containing natural graphite and artificial graphite as negative electrode active material particles,
the negative electrode active material layer comprising:
a region facing the positive electrode active material layer and a region not facing the positive electrode active material layer, said regions contacting the negative electrode current collector and being disposed in a same plane extending in a direction normal to a direction in which the negative electrode active material layer and the negative electrode current collector are laminated, wherein
the region facing the positive electrode active material layer contains the natural graphite in a larger proportion than the region not facing the positive electrode active material layer, and
the region not facing the positive electrode active material layer contains the artificial graphite in a larger proportion than the region facing the positive electrode active material layer.

2. The lithium-ion secondary battery according to claim 1 , wherein the region of the negative electrode active material layer facing the positive electrode active material layer contains the natural graphite in a weight proportion of equal to or greater than 90% of the total weight of the natural graphite and the artificial graphite.

3. The lithium-ion secondary battery according to claim 1 , wherein the region of the negative electrode active material layer not facing the positive electrode active material layer contains the artificial graphite in a weight proportion of equal to or greater than 90% of the total weight of the natural graphite and the artificial graphite.

4. The lithium-ion secondary battery according to claim 1 , wherein as determined by Raman spectroscopy, the natural graphite has an R value of from 0.2 to 0.6, and the artificial graphite has an R value of less than or equal to 0.2.

5. The lithium-ion secondary battery according to claim 4 , wherein the ratio (Ra/Rb) of a mean R value (Ra) and a mean R value (Rb) is (Ra/Rb)≥1.2, where the mean R value (Ra) is the mean of the R values of the negative electrode active material particles used in the region of the negative electrode active material layer facing the positive electrode active material layer, and the mean R value (Rb) is the mean of the R values of the negative electrode active material particles used in the region of the negative electrode active material layer not facing the positive electrode active material layer.

6. The lithium-ion secondary battery according to claim 1 , wherein:
the negative electrode active material layer contains a binder; and
the region of the negative electrode active material layer not facing the positive electrode active material layer contains the binder in a greater amount than the region of the negative electrode active material layer facing the positive electrode active material layer.

7. The lithium-ion secondary battery according to claim 1 , wherein the natural graphite is at least partially covered with an amorphous carbon film.

8. A battery module comprising a plurality of the lithium-ion secondary batteries according to claim 1 .

9. A vehicle drive battery comprising the lithium-ion secondary battery according to claim 1 .

Assignees

• Takahata Koji
• Ochiai Akihiro
• Toyota Motor Co Ltd

Inventors

• Takahata Koji
• Ochiai Akihiro

Classifications

• H01M10/058

  Construction or manufacture · CPC title

• Y02T10/7011

  Cross-Sectional Technologies · mapped topic

• H01M10/052

  Li-accumulators · CPC title

• H01M4/1393

  of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx · CPC title

• H01M4/366

  as layered products · CPC title