Non-aqueous electrolyte secondary battery

Patent metadata

Field	Value
Publication number	US-10535867-B2
Application number	US-201815870457-A
Country	US
Kind code	B2
Filing date	Jan 12, 2018
Priority date	Jan 13, 2017
Publication date	Jan 14, 2020
Grant date	Jan 14, 2020

Abstract

The present teaching provides a non-aqueous electrolyte secondary battery provided with a non-aqueous electrolyte solution having a composition able to achieve high battery performance even in an extremely low temperature region (for example, −30° C. or lower). The non-aqueous electrolyte solution disclosed herein contains, as non-aqueous solvents, ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) and ethyl propionate (EP), and when the total volume of the non-aqueous solvents is 100 vol. %, the content of EC is 20 to 30 vol. %, the content of PC is 5 to 10 vol. %, the content of EP is 5 to 10 vol. %, and the content of DMC+EMC is 50 to 70 vol. %.

First claim

What is claimed is:

1. A non-aqueous electrolyte secondary battery, comprising:
a positive electrode active material layer comprising a positive electrode active material;
a negative electrode active material layer comprising a negative electrode active material, where the negative electrode active material is spherical natural graphite coated with amorphous carbon; and
a non-aqueous electrolyte solution containing a non-aqueous solvent and an electrolyte, wherein the non-aqueous solvent:
contains at least ethylene carbonate (EC) and propylene carbonate (PC) as cyclic carbonate-based solvents,
contains at least dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) as linear carbonate-based solvents, and
contains at least ethyl propionate (EP) as an ester-based solvent, and
when the total volume of the non-aqueous solvent is 100 vol. %:
the content of EC is 20 to 30 vol. %;
the content of PC is 5 to 10 vol. %;
the content of EP is 5 to 10 vol. %; and
the content of DMC+EMC is 50 to 70 vol. %.

2. The non-aqueous electrolyte secondary battery according to claim 1 , wherein the content of the dimethyl carbonate (DMC) and the content of the ethyl methyl carbonate (EMC) are both 25 to 35 vol. % based on the total volume of the non-aqueous solvent.

3. The non-aqueous electrolyte secondary battery according to claim 1 , wherein the non-aqueous electrolyte solution has a freezing point of lower than −40° C. and not lower than −60° C.

4. The non-aqueous electrolyte secondary battery according to claim 1 , wherein the non-aqueous electrolyte solution has an ionic conductivity (mS/cm) of 1.0 or more at −40° C.

5. The non-aqueous electrolyte secondary battery according to claim 1 , wherein the positive electrode active material has an average particle diameter (D50) of from 1 μm to 20 μm.

6. The non-aqueous electrolyte secondary battery according to claim 1 , wherein the positive electrode active material has a specific surface area of from 0.1 m 2 /g to 5 m 2 /g.

7. The non-aqueous electrolyte secondary battery according to claim 1 , wherein the positive electrode active material layer has a void ratio of from 10% to 50%.

8. The non-aqueous electrolyte secondary battery according to claim 1 , wherein the positive electrode active material layer comprises from 60 mass % to 99 mass % positive electrode active material based on the total mass of the positive electrode active material layer.

9. The non-aqueous electrolyte secondary battery according to claim 1 , wherein the positive electrode active material comprises LiCrMnO 4 .

10. The non-aqueous electrolyte secondary battery according to claim 1 , wherein the negative electrode active material has an average particle diameter (D50) of from 1 μm to 50 μm.

11. The non-aqueous electrolyte secondary battery according to claim 1 , wherein the negative electrode active material has a specific surface area of from 1 m 2 /g to 10 m 2 /g.

12. The non-aqueous electrolyte secondary battery according to claim 1 , wherein the negative electrode active material layer has a void ratio of from 5% to 50%.

13. The non-aqueous electrolyte secondary battery according to claim 1 , wherein the negative electrode active material layer comprises from 50 mass % to 99 mass % negative electrode active material based on the total mass of the negative electrode active material layer.

14. The non-aqueous electrolyte secondary battery according to claim 1 , wherein the electrolyte comprises a sodium salt.

15. The non-aqueous electrolyte secondary battery according to claim 14 , wherein the sodium salt comprises NaPF 6 .

16. The non-aqueous electrolyte secondary battery according to claim 1 , further comprising at least one separator sheet comprising a three-layer structure comprising polypropylene/polyethylene/polypropylene.

Assignees

• Toyota Motor Co Ltd

Inventors

• Ishii Kenta
• Ohsawa Ryosuke
• Abe Koji
• Shimamoto Kei
• Babazono Makoto

Classifications

• H01M10/0525 Primary

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M4/133 Primary

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

• H01M10/0569 Primary

  characterised by the solvents · CPC title

• H01M4/366

  as layered products · CPC title

• H01M2300/0042

  Four or more solvents · CPC title