Lithium ion secondary battery

Patent metadata

Field	Value
Publication number	US-11362318-B2
Application number	US-201716332987-A
Country	US
Kind code	B2
Filing date	Aug 3, 2017
Priority date	Sep 14, 2016
Publication date	Jun 14, 2022
Grant date	Jun 14, 2022

Abstract

A purpose of one embodiment of the present invention is to provide a lithium ion secondary battery which comprises lithium nickel composite oxide having high nickel content in a positive electrode and has excellent battery characteristics. The first lithium ion secondary battery of the present invention comprises a lithium nickel composite oxide represented by the following formula and carbon nanotubes in a positive electrode, wherein a ratio (a)/(b) of an average length (a) of the carbon nanotubes to an average particle size (b) of primary particles of the lithium nickel composite oxide is 0.5 or more,

Li y Ni (1-x) M x O 2
wherein 0≤x≤0.4, 0<y≤1.2, and M is at least one element selected from the group consisting of Co, Al, Mn, Fe, Ti, and B.

First claim

The invention claimed is:

1. A lithium ion secondary battery, comprising:
a lithium nickel composite oxide represented by the following formula, and carbon nanotubes in a positive electrode mixture layer in a positive electrode,
wherein a ratio (a)/(b) of an average length (a) of the carbon nanotubes to an average particle size (b) of primary particles of the lithium nickel composite oxide is 0.5 or more, and an average length of the carbon nanotubes is 100 nm or more and 840 nm or less,
an average diameter of outermost cylinders of the carbon nanotubes is 40 nm or less,
an average split width of gaps between the primary particles is 50 nm or more and 700 nm or less,
an average particle size of secondary particles of the lithium nickel composite oxide is 1 μm or more and 16 μm or less, and
the carbon nanotubes are disposed within the gaps between the primary particles of the lithium nickel composite oxide;
Li y Ni (1-x) M x O 2

wherein 0≤x≤0.4, 0<y≤1.2, and M is at least one element selected from the group consisting of Co, Al, Mn, Fe, Ti, and B.

2. The lithium ion secondary battery according to claim 1 , wherein an average particle size of the primary particles is 50 nm or more and 700 nm or less.

3. The lithium ion secondary battery according to claim 1 , wherein a density of a positive electrode mixture layer is 3.25 g/cm 3 or more.

4. The lithium ion secondary battery according to claim 1 , wherein an average split width of the primary particles before charging-discharging the lithium ion secondary battery is 50 nm or more and 700 nm or less.

5. A vehicle equipped with the lithium ion secondary battery according to claim 1 .

6. A method for manufacturing a lithium ion secondary battery, comprising the steps of:
preparing a slurry comprising a positive electrode active material comprising a lithium nickel composite oxide represented by the following formula, a conductive material comprising carbon nanotubes, a binder and a solvent, and applying the slurry to a positive electrode current collector to form a positive electrode mixture layer,
obtaining a positive electrode by pressing the positive electrode mixture layer,
fabricating an electrode element by stacking the positive electrode and a negative electrode via a separator, and
encapsulating the electrode element and an electrolyte solution into an outer package,
wherein a ratio (a)/(b) of an average length (a) of the carbon nanotubes to an average particle size (b) of primary particles of the lithium nickel composite oxide is 0.5 or more, and an average length of the carbon nanotubes is 100 nm or more and 840 nm or less,
an average diameter of outermost cylinders of the carbon nanotubes is 40 nm or less,
an average split width of gaps between the primary particles is 50 nm or more and 700 nm or less,
an average particle size of secondary particles of the lithium nickel composite oxide is 1 μm or more and 16 μm or less, and
the carbon nanotubes are disposed within the gaps between the primary particles of the lithium nickel composite oxide;
Li y Ni (1-x) M x O 2

wherein 0≤x≤0.4, 0<y≤1.2, and M is at least one element selected from the group consisting of Co, Al, Mn, Fe, Ti, and B.

7. The lithium ion secondary battery according to claim 1 , wherein the carbon nanotubes form a conductive path in the gaps between the primary particles of the lithium nickel composite oxide.

Assignees

• Nec Corp

Inventors

• Azami Takeshi

Classifications

• H01M4/1391

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

• H01M4/131 Primary

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

• H01M4/62

  Selection of inactive substances as ingredients for active masses, e.g. binders, fillers · CPC title

• H01M4/525

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

• H01M10/0525

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