Lithium secondary battery and positive electrode for the battery

Patent metadata

Field	Value
Publication number	US-9559359-B2
Application number	US-200913499323-A
Country	US
Kind code	B2
Filing date	Oct 2, 2009
Priority date	Oct 2, 2009
Publication date	Jan 31, 2017
Grant date	Jan 31, 2017

Abstract

The lithium secondary battery positive electrode provided by the present invention has a positive electrode collector and a positive active material layer formed on the collector. The positive active material layer is composed of a matrix phase containing at least one particulate positive active material and at least one binder, and an aggregate phase dispersed in the matrix phase, constituted by aggregation of at least one particulate positive active material and containing substantially no binder.

First claim

The invention claimed is:

1. A positive electrode for a lithium secondary battery, comprising a positive electrode collector and a positive active material layer formed on this collector, wherein the positive active material layer is composed of:
a matrix phase comprising positive active material fine particles having an average particle diameter of 1 μm or less and at least one binder; and
a plurality of aggregates being distinct from the matrix phase, and each of the plurality of aggregates being composed of positive active material particles having an average particle diameter of 5 μm to 50 μm and containing substantially no binder,
wherein the plurality of aggregates are present in a state of being dispersed independently from one another in the positive active material layer, and wherein each of the plurality of aggregates is enveloped by the matrix phase.

2. The positive electrode according to claim 1 , wherein the matrix phase and the aggregates both contain at least one positive active material of the same composition.

3. The positive electrode according to claim 1 , wherein a conductive coat of a conductive material is formed on the surface of the positive active material fine particles of the matrix phase and the positive active material particles of the aggregates.

4. The positive electrode according to claim 3 , wherein the conductive material is a carbonaceous material, and a conductive carbonaceous coat is formed on the surface of the positive active material fine particles of the matrix phase and the positive active material particles of the aggregates.

5. The positive electrode according to claim 4 , wherein the at least one binder contained in the matrix phase is a polymer compound having at least one functional group, and
the binder composed of the polymer compound binds molecularly to carbon atoms constituting the carbonaceous coat on the positive active material fine particles contained in the matrix phase, thereby forming, in the matrix phase, a complex compound composed of the binder that binds molecularly to these carbon atoms and a carbon network constituting the carbonaceous coat including these carbon atoms.

6. The positive electrode according to claim 5 , wherein the matrix phase contains, as the binder, at least one polymer compound having hydroxyl groups and/or carboxyl groups.

7. The positive electrode according to claim 6 , wherein a vinylidene fluoride polymer having introduced therein hydroxyl groups and/or carboxyl groups and having vinylidene fluoride as a principal monomer component is included as the polymer compound.

8. The positive electrode according to claim 5 , wherein a network of the binder is formed by crosslinking of the polymer compound with itself in the matrix phase.

9. The positive electrode according to claim 1 , wherein at least one kind of the positive active material is a compound represented by the general formula:
LiMAO 4   (1)

wherein M is one or two or more elements including at least one metal element selected from the group consisting of Fe, Co, Ni and Mn, and A is one or two or more elements selected from the group consisting of P, Si, S and V.

10. A lithium secondary battery comprising the positive electrode according to claim 1 .

11. A vehicle comprising the lithium secondary battery according to claim 10 .

Assignees

• Hara Tomitaro
• Tsujiko Akira
• Abe Takeshi
• Yuasa Sachie
• Wasada Keiko
• Toyota Motor Co Ltd

Inventors

• Hara Tomitaro
• Tsujiko Akira
• Abe Takeshi
• Yuasa Sachie
• Wasada Keiko

Classifications

• H01M4/1397

  of electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy · CPC title

• H01M10/613

  Cooling or keeping cold · CPC title

• H01M4/5825 Primary

  Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines · CPC title

• H01M10/625

  Vehicles · CPC title

• H01M4/625

  Carbon or graphite · CPC title