Positive electrode and secondary battery including the positive electrode

Patent metadata

Field	Value
Publication number	US-12512460-B2
Application number	US-201916959301-A
Country	US
Kind code	B2
Filing date	Feb 19, 2019
Priority date	Feb 19, 2018
Publication date	Dec 30, 2025
Grant date	Dec 30, 2025

Abstract

A positive electrode includes a current collector and a positive electrode active material layer disposed on the current collector, wherein the positive electrode active material layer includes a positive electrode active material, carbon nanotube, and a binder, the binder includes polyvinylidene fluoride which has a weight average molecular weight of 720,000 g/mol to 980,000 g/mol, a BET specific surface area of the carbon nanotube is 140 m 2 /g to 195 m 2 /g, and the positive electrode satisfies the following Formula 1:

1.3≤ B/A ≤3.4  [Formula 1]
in Formula 1, B is an amount (wt %) of the polyvinylidene fluoride in the positive electrode active material layer, and A is an amount (wt %) of the carbon nanotube in the positive electrode active material layer.

First claim

The invention claimed is:

1 . A positive electrode comprising a current collector and a positive electrode active material layer disposed on the current collector,
wherein the positive electrode active material layer comprises a positive electrode active material, a carbon nanotube, and a binder, the binder comprises polyvinylidene fluoride which has a weight average molecular weight of 720,000 g/mol to 980,000 g/mol, a BET specific surface area of the carbon nanotube is 140 m 2 /g to 195 m 2 /g, and the positive electrode satisfies the following Formula 1:
1.3≤ B/A≤ 3.4  [Formula 1]

wherein, in the Formula 1, B is an amount (wt %) of the polyvinylidene fluoride in the positive electrode active material layer, and A is an amount (wt %) of the carbon nanotube in the positive electrode active material layer.

2 . The positive electrode according to claim 1 , wherein the carbon nanotube is a bundle type carbon nanotube comprising a plurality of carbon nanotube units.

3 . The positive electrode according to claim 2 , wherein an average diameter of a carbon nanotube unit of the plurality of carbon nanotube units is from 1 nm to 30 nm.

4 . The positive electrode according to claim 1 , wherein the positive electrode satisfies the following Formula 2:
1.3≤ B/A≤ 1.85  [Formula 2]
wherein, in the Formula 2, B is an amount (wt %) of the polyvinylidene fluoride in the positive electrode active material layer, and A is an amount (wt %) of the carbon nanotube in the positive electrode active material layer.

5 . The positive electrode according to claim 1 , wherein the positive electrode active material comprises Li[Nix1Mny1Coz1]O2, wherein 0.40≤x1≤0.70, 0.15≤y1≤0.30, 0.15≤z1≤0.30, and x1+y1+z1=1.

6 . The positive electrode according to claim 1 , wherein the positive electrode active material is comprised in 95.6 wt % to 99.0 wt % in the positive electrode active material layer.

7 . The positive electrode according to claim 1 , wherein an average particle diameter (D50) of the positive electrode active material is from 3 μm to 20 μm.

8 . The positive electrode according to claim 1 , wherein the binder comprises a non fluorine-based binder.

9 . The positive electrode according to claim 8 , wherein the non fluorine-based binder is at least one of nitrile butadiene rubber or hydrogenated-nitrile butadiene rubber.

10 . A secondary battery comprising:
the positive electrode according to claim 1 ; a negative electrode; a separator disposed between the positive electrode and the negative electrode; and an electrolyte.

11 . The positive electrode according to claim 1 , wherein the positive electrode active material layer has a powder resistance of 42.0 Ω·cm to 94.2 Ω·cm.

12 . The positive electrode according to claim 1 , wherein the positive electrode has an adhesiveness of 21.1 gf/20 mm to 33.0 gf/20 mm.

Assignees

• Lg Chemical Ltd
• Lg Energy Solution Ltd

Inventors

• Baek Joo Yul
• Lim Jun Muk
• Lee Chang Ju
• Oh Il Geun
• Kim Je Young
• Choy Sang Hoon

Classifications

• H01M2004/028

  Positive electrodes · CPC title

• H01M2004/021

  Physical characteristics, e.g. porosity, surface area · CPC title

• H01M10/0525

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

• H01M4/625

  Carbon or graphite · CPC title

• H01M4/623

  fluorinated polymers · CPC title