Lithium secondary battery

Patent metadata

Field	Value
Publication number	US-11322773-B2
Application number	US-201716083300-A
Country	US
Kind code	B2
Filing date	Mar 9, 2017
Priority date	Mar 10, 2016
Publication date	May 3, 2022
Grant date	May 3, 2022

Abstract

Provided is a lithium ion secondary battery that has excellent cycle characteristics and employs a silicon material for a negative electrode. This lithium ion secondary battery is characterized by having a negative electrode comprising a plate-like artificial graphite and a material comprising silicon as a constituent element, wherein at least some of particles of the plate-like artificial graphite are bent and have a crease on a plate face.

First claim

The invention claimed is:

1. A lithium ion secondary battery comprising a negative electrode, the negative electrode comprising:
a plurality of first artificial graphite particles having a plate-like shape;
a plurality of second artificial graphite particles having a plate-like shape and having capacities different from the plurality of first artificial graphite particles; and
a material comprising silicon as a constituent element,
wherein 30 weight % or more of the plurality of first artificial graphite particles are bent and have only one crease on a plate face,
further wherein the crease connects two points on an outline of the plate face, and the plate face forms an angle within a range of 110° or more and 170° or less via the crease.

2. The lithium ion secondary battery according to claim 1 , wherein a content of the bent artificial graphite particle is 3 weight % or more of a total amount of the plurality of first artificial graphite particles and the plurality of second artificial graphite particles contained in the negative electrode.

3. The lithium ion secondary battery according to claim 1 , wherein the material comprising silicon as a constituent element is selected from the group consisting of silicon oxides, silicon alloys and combinations thereof.

4. The lithium ion secondary battery according to claim 1 , wherein the plurality of first artificial graphite particles has a 50% particle size of 7 μm or more and 11 μm or less.

5. The lithium ion secondary battery according to claim 1 , wherein the plurality of first artificial graphite particles has a BET specific surface area of 5 m 2 /g or more and 40 m 2 /g or less.

6. The lithium ion secondary battery according to claim 1 , wherein D50A that represents a 50% particle size of the plurality of first artificial graphite particles and D50G that represents a 50% particle size of the plurality of second artificial graphite particles satisfy a relational equation: 0.1≤D50G/D50A≤2.0.

7. The lithium ion secondary battery according to claim 1 , wherein the plurality of second artificial graphite particles has a BET specific surface area of 0.5 m 2 /g or more and 9 m 2 /g or less.

8. A vehicle equipped with the secondary battery according to claim 1 .

9. A method for manufacturing a lithium ion secondary battery, comprising the steps of:
fabricating an electrode element by stacking a negative electrode and a positive electrode via a separator, and
encapsulating the electrode element and an electrolyte solution into an outer package,
wherein the negative electrode comprises:
a plurality of first artificial graphite particles having a plate-like shape,
a plurality of second artificial graphite particles having a plate-like shape and having capacities different from the plurality of first artificial graphite particles; and

a material comprising silicon as a constituent element,
wherein 30 weight % or more of the plurality, of first artificial graphite particles are bent and have only one crease on a plate face,
further wherein the crease connects two points on an outline of the plate face, and the plate face forms an angle within a range of 110° or more and 170° or less via the crease.

Assignees

• Nec Corp

Inventors

• Azami Takeshi

Classifications

• H01M4/131

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

• H01M4/134

  Electrodes based on metals, Si or alloys · CPC title

• H01M10/0585

  of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators · CPC title

• Y02E60/10

  Energy storage using batteries · CPC title

• H01M2220/20

  Batteries in motive systems, e.g. vehicle, ship, plane · CPC title