Positive electrode active material slurry including two types of binders and positive electrode prepared therefrom

Patent metadata

Field	Value
Publication number	US-10367200-B2
Application number	US-201515112034-A
Country	US
Kind code	B2
Filing date	Oct 2, 2015
Priority date	Oct 2, 2014
Publication date	Jul 30, 2019
Grant date	Jul 30, 2019

Abstract

The present invention relates to positive electrode active material slurry including two different types of binders in a specific ratio and having a high solid concentration and low viscosity, a positive electrode including a positive electrode active material layer formed therefrom, and a lithium secondary battery including the positive electrode.

First claim

What is claimed is:

1. A positive electrode active material slurry comprising:
a positive electrode active material;
a first binder;
a second binder; and
an organic solvent,
wherein the first binder is a fluorine-based binder,
the second binder is a butadiene rubber-based binder, and
the first binder and the second binder have a weight ratio of 9:1 to 7:3,
wherein the positive electrode active material is included in 50% by weight to 65% by weight with respect to total solid content of the positive electrode active material slurry,
wherein the positive electrode active material is a lithium iron phosphate-based positive electrode active material represented by the following Chemical Formula 1:
Li 1+a Fe 1-x M x (PO 4-b )X b   [Chemical Formula 1]

wherein, in Chemical Formula 1,
M is Al, Mg, Ni, Co, Mn, Ti, Ga, V, Nb, Zr, Ce, In, Zn, Y or a combination thereof,
X is F, S, N or a combination thereof,
a is −0.5≤a≤0.5,
b is 0≤b≤0.1, and
x is 0≤x≤0.5.

2. The positive electrode active material slurry of claim 1 , wherein the positive electrode active material is LiFePO 4 , LiFeMnPO 4 , LiFeMgPO 4 , LiFeNiPO 4 , LiFeAlPO 4 or LiFeCoNiMnPO 4 .

3. The positive electrode active material slurry of claim 1 , wherein the first binder is one or more types selected from the group consisting of polyvinylidene fluoride (PVDF), a vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HEP), chlorotrifluoroethylene (CFTF) and polytetrafluoroethylene (PTFE).

4. The positive electrode active material slurry of claim 1 , wherein the second binder is one or more types selected from the group consisting of styrene-butadiene rubber and nitrile-butadiene rubber.

5. The positive electrode active material slurry of claim 1 , wherein the second binder is included in 20 parts by weight to 30 parts by weight with respect to 100 parts by weight of the whole positive electrode active material slurry.

6. The positive electrode active material slurry of claim 1 , further comprising a conductor.

7. The positive electrode active material slurry of claim 1 , wherein the organic solvent is one or more types selected from the group consisting of N-methylpyrrolidone (NMP) and N,N-dimethylacetamide (DMAc).

8. The positive electrode active material slurry of claim 1 , which has a solid concentration of 55% to 65%.

9. The positive electrode active material slurry of claim 1 , which has viscosity of 5,000 cps to 20,000 cps.

10. A positive electrode comprising a positive electrode active material layer formed from the positive electrode active material slurry of claim 1 .

11. A lithium secondary battery comprising:
the positive electrode of claim 10 ;
a negative electrode; and
a separator provided between the positive electrode and the negative electrode.

Assignees

• Lg Chemical Ltd

Inventors

• Jung Do Hwa
• Lee Hyun Won
• Choy Sang Hoon

Classifications

• H01M10/0525

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

• H01M10/052

  Li-accumulators · CPC title

• H01M4/5825 Primary

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

• H01M4/623

  fluorinated polymers · CPC title

• H01M4/62 Primary

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