Lithium ion secondary battery

Patent metadata

Field	Value
Publication number	US-11824192-B2
Application number	US-201816760791-A
Country	US
Kind code	B2
Filing date	Oct 31, 2018
Priority date	Nov 1, 2017
Publication date	Nov 21, 2023
Grant date	Nov 21, 2023

Abstract

A purpose of the present invention is to provide a lithium ion secondary battery having more improved life characteristics while suppressing gelation of an electrode mixture slurry in a manufacturing process. The lithium ion secondary battery according to the present invention comprises a positive electrode having a positive electrode mixture layer comprising a layered lithium-nickel composite oxide in which a proportion of nickel in metals other than lithium is 80 mol % or more; LiOH; Li 2 CO 3 ; and a chlorine-containing polyvinylidene fluoride-based polymer, wherein a content of LiOH in the positive electrode mixture layer and a content of Li 2 CO 3 in the positive electrode mixture layer are each 0.1 weight % or more and 2.1 weight % or less, a total content of LiOH and Li 2 CO 3 in the positive electrode mixture layer is 0.2 weight % or more and 4.2 weight % or less, and a content of chlorine in the positive electrode mixture layer is 30 μg/g or more and 120 μg/g or less.

First claim

The invention claimed is:

1. A lithium ion secondary battery comprising:
a positive electrode,
a negative electrode, and
an electrolyte solution, wherein
the positive electrode has a positive electrode mixture layer comprising:
a layered lithium-nickel composite oxide in which a proportion of nickel in metals other than lithium is 80 mol % or more;
LiOH;
Li 2 CO 3 ;
a chlorine-free polyvinylidene fluoride-based polymer; and
a chlorine-containing polyvinylidene fluoride-based polymer,

wherein a content of LiOH in the positive electrode mixture layer and a content of Li 2 CO 3 in the positive electrode mixture layer are each 0.1 weight % or more and 2.1 weight % or less, a total content of LiOH and Li 2 CO 3 in the positive electrode mixture layer is 0.2 weight% or more and 4.2 weight % less, and a content of chlorine in the positive electrode mixture layer is 30 μg/g or more and 120 μg/g or less,
the amount of the chlorine-containing polyvinylidene fluoride-based polymer is 0.10 weight % or more to 0.45 weight % or less of the positive electrode mixture layer,
a total content of the chlorine-containing polyvinylidene fluoride-based polymer and the chlorine-free polyvinylidene fluoride-based polymer in the positive electrode mixture layer is 1.5 weight % or more and 2.5 weight % or less, and
the negative electrode comprises silicon oxide having a surface coated with carbon.

2. The lithium ion secondary battery according to claim 1 , wherein the layered lithium-nickel composite oxide is represented by the following formula, Li y Ni (1-x) M x O 2
wherein 0≤x≤0.2, 0<y≤1.2, and M is at least one element selected from the group consisting of Co, Al and Mn.

3. The lithium ion secondary battery according to claim 1 , wherein a density of the positive electrode mixture layer is 3.45 g/cm 3 or more and 4.0 g/c 3 or less.

4. The lithium ion secondary battery according to claim 1 , wherein the positive electrode mixture layer comprises a carbon black having an average primary particle size of 20 nm or more and 80 nm or less and a specific surface area of 25 m 2 /g or more and 400 m 2 /g or less in an amount of 0.1 weight % or more and 2.0 weight % or less.

5. The lithium ion secondary battery according to claim 1 , wherein the positive electrode mixture layer comprises a carbon nanotube having an average diameter of 5 nm or more and 40 nm or less and a specific surface area of 100 m 2 /g or more and 400 m 2 /g or less in an amount of 0.03 weight % or more and 2.0 weight % or less.

6. The lithium ion secondary battery according to claim 1 , wherein the positive electrode mixture layer comprises a plate-like graphite having an average primary particle size of 1 μm or more and 6 μm or less and a specific surface area of 10m 2 /g or more and 40 m 2 /g or less in an amount of 0.03 weight% or more and 2.0 weight % or less.

7. The lithium ion secondary battery according to claim 1 , wherein the positive electrode mixture layer comprises a ketjenblack having an average primary particle size of 35 nm or more and 45 nm or less and a specific surface area of 750 m 2 /g or more and 850 m 2 /g or less in an amount of 0.1 weight % or more and 2.0 weight % or less.

8. The lithium ion secondary battery according to claim 1 , wherein the positive electrode mixed layer comprises a conductive assisting agent in an amount of 0.03 weight % or more and 2.5 weight % or less.

9. The lithium ion secondary battery according to claim 8 , wherein the conductive assisting agent is one or more selected from the group consisting of:
a carbon black having an average primary particle size of 20 nm or more and 80 nm or less and a specific surface area of 25 m 2 /g or more and 400 m 2 /g or less in an amount of 0.1 weight % or more and 2.0 weight % or less,
a carbon nanotube having an average diameter of 5 nm or more and 40 nm or less and a specific surface area of 100 m 2 /g or more and 400 m 2 /g or less in an amount of 0.03 weight % or more and 2.0 weight % or less,
a plate-like graphite having an average primary particle size of 1 μm or more and 6 μm or less and a specific surface area of 10 m 2 /g or more and 40 m 2 /g or less in an amount of 0.03 weight % or more and 2.0 weight % or less, and
a ketjenblack having an average primary particle size of 35 nm or more and 45 nm or less and a specific surface area of 750 m 2 /g or more and 850 m 2 /g or less in an amount of 0.1 weight % or more and 2.0 weight % or less.

10. The lithium ion secondary battery according to claim 1 , wherein the electrolyte solution comprises fluoroethylene carbonate.

11. The lithium ion secondary battery according to claim 1 , wherein an amount of the silicon oxide having a surface coated with carbon is 10 weight % or more based on the total amount of the negative electrode active material.

12. The lithium ion secondary battery according to claim 1 , wherein the chlorine-free polyvinylidene fluoride-based polymer does not comprise polyvinylidene fluoride (PVdF).

13. The lithium ion secondary battery according to claim 1 , wherein the positive electrode mixture layer does not include polyvinylidene fluoride (PVdF).

14. A method for manufacturing a lithium ion secondary battery, comprising the steps of:
fabricating an electrode element by stacking a positive electrode and a negative electrode via a separator, and
enclosing the electrode element and an electrolyte solution into an outer package,
wherein the positive electrode has a positive electrode mixture layer comprising:
a layered lithium-nickel composite oxide in which a proportion of nickel in metals other than lithium is 80 mol % or more;
LiOH;
Li 2 CO 3 ;
a chlorine-free polyvinylidene fluoride-based polymer; and
a chlorine-containing polyvinylidene fluoride-based polymer,

a content of LiOH in the positive electrode mixture layer and a content of Li 2 CO 3 in the positive electrode mixture layer are each 0.1 weight % or more and 2.1 weight % or less, a total content of LiOH and Li 2 CO 3 in the positive electrode mixture layer is 0.2 weight % or more and 4.2 weight % less, and a content of chlorine in the positive electrode mixture layer is 30 μg/g or more and 120 μg/g or less,
an amount of the chlorine-containing polyvinylidene fluoride-based polymer is 0.10 weight % or more to 0.45 weight % or less of the positive electrode mixture layer,
a total content of the chlorine-containing polyvinylidene fluoride-based polymer and the chlorine-free polyvinylidene fluoride-based polymer in the positive electrode mixture layer is 1.5 weight % or more and 2.5 weight % or less, and
the negative electrode comprises silicon oxide having a surface coated with carbon.

15. The lithium ion secondary battery according to claim 14 , wherein the chlorine-free polyvinylidene fluoride-based polymer is vinylidene fluoride-hexafluoropropylene copolymer.

Assignees

• Nec Corp

Inventors

• Azami Takeshi

Classifications

• H01M4/525 Primary

  of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy · CPC title

• H01M4/131

  Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx · CPC title

• H01M4/1391

  of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx · CPC title

• H01M4/366

  as layered products · CPC title

• H01M4/505

  of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy · CPC title