Nonaqueous electrolyte secondary battery

Patent metadata

Field	Value
Publication number	US-9673435-B2
Application number	US-201114115220-A
Country	US
Kind code	B2
Filing date	May 2, 2011
Priority date	May 2, 2011
Publication date	Jun 6, 2017
Grant date	Jun 6, 2017

Abstract

A nonaqueous electrolyte secondary battery 100 according to the present invention is provided with an electrode assembly 80 having a structure in which a positive electrode 10 and a negative electrode 20 are stacked with a separator 30 interposed therebetween. A porous filler layer 32 is formed between the positive electrode 10 and the separator 30 . The filler layer 32 contains a filler made of an inorganic material and contains a binder. The relationship T>D holds where T is the average thickness of the filler layer 32 and D is the average particle diameter of a positive electrode active material 15 present in the positive electrode 10 facing the filler layer 32 , and a pressure applied to the electrode assembly 80 in the stacking direction is set to at least 0.1 MPa.

First claim

The invention claimed is:

1. A nonaqueous electrolyte secondary battery, comprising
an electrode assembly having a structure in which a positive electrode and a negative electrode are stacked with a separator interposed therebetween, wherein
a thickness of the separator is from more than 20 μm to not more than 30 μm,
a porous filler layer is disposed between the positive electrode and the separator,
the filler layer contains a filler made of an inorganic material and contains a binder,
an average particle diameter of the filler is from at least 0.5 μm to not more than 2 μm,
the proportion of the filler in the filler layer as a whole is at least 90 mass %,
a porosity of the filler layer is from 50% to 60%,
an average thickness T of the filler layer is from at least 6 μm to not more than 20 μm, an average particle diameter D of a positive electrode active material present in the positive electrode facing the filler layer is at least 1 μm, and the relationship T>D holds, and
the separator is thicker than the filler layer, and the total thickness of the filler layer and the separator is from 26 μm to 40 μm, and
a pressure applied to the electrode assembly in the stacking direction is set to at least 0.1 MPa.

2. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the difference between the average thickness T of the filler layer and the average particle diameter D of the positive electrode active material is at least 0.5 μm.

3. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the average thickness T of the filler layer is at least 9 μm, and
the average particle diameter D of the positive electrode active material is not more than 8.3 μm.

4. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the filler incorporated in the filler layer is at least one metal compound selected from the group consisting of alumina, magnesia, zirconia, silica, boehmite, and titania.

5. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the shape of the positive electrode active material is spherical or oval spherical.

6. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the positive electrode has, as the positive electrode active material, a lithium transition metal complex oxide that contains at least one metal element selected from the group consisting of nickel, cobalt, and manganese.

7. A battery pack comprising a plurality of the nonaqueous electrolyte secondary batteries according to claim 1 connected in series, wherein each of the nonaqueous electrolyte secondary batteries is provided with the electrode assembly and a battery case that houses the electrode assembly and a nonaqueous electrolyte, and
a retaining pressure applied to a surface of the battery case is set to at least 0.1 MPa.

8. The battery pack according to claim 7 , wherein the battery case is made of aluminum or an aluminum alloy.

9. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the filler layer further contains at least one thickener chosen from carboxymethyl cellulose and polyethylene oxide.

Assignees

• Ueki Tomoyoshi
• Fujita Hideaki
• Shimamura Harunari
• Toyota Motor Co Ltd

Inventors

• Ueki Tomoyoshi
• Fujita Hideaki
• Shimamura Harunari

Classifications

• H01M4/485 Primary

  of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy (H01M4/505, H01M4/525 take precedence) · CPC title

• H01M50/451

  comprising layers of only organic material and layers containing inorganic material · CPC title

• H01M50/491 Primary

  Porosity · CPC title

• H01M50/489

  Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties · CPC title

• H01M2004/025

  with shapes other than plane or cylindrical · CPC title