Positive electrode slurry composition for secondary battery, and positive electrode for secondary battery and secondary battery which are prepared by using the same

Patent metadata

Field	Value
Publication number	US-12424670-B2
Application number	US-202016809075-A
Country	US
Kind code	B2
Filing date	Mar 4, 2020
Priority date	Nov 24, 2017
Publication date	Sep 23, 2025
Grant date	Sep 23, 2025

Abstract

A positive electrode slurry composition for a secondary battery which includes a positive electrode active material, a carbon-based conductive agent having a specific surface area (Brunauer-Emmett-Teller (BET)) of 100 m2/g to 200 m2/g, a binder, and a nitrile-based copolymer which has an electrolyte solution swelling degree defined by Equation (1) of 200% or less and does not contain a functional group other than a cyano group is provided:electrolyte solution swelling degree (%)={(W1−W0)/W0}×100  Equation (1)wherein, W0 is an initial weight of a polymer film prepared from the nitrile-based copolymer, and W1 is a weight of the polymer film which is measured after storing the polymer film at 60° for 48 hours in an electrolyte solution.

First claim

The invention claimed is:

1. A secondary battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte,
wherein the positive electrode comprises a positive electrode active material layer formed by using a positive electrode slurry composition, wherein the positive electrode slurry composition, comprises:
a positive electrode active material,
carbon nanotubes having a specific surface area measured by a Brunauer-Emmett-Teller (BET) of 150 m 2 /g to 190 m 2 /g,
a binder, and
a nitrile-based copolymer which has an electrolyte solution swelling degree defined by Equation (1) of 200% or less and does not contain a functional group other than a cyano group:
electrolyte solution swelling degree (%)={( W 1 −W 0 )/ W 0 }×100  Equation (1):

wherein, in Equation (1), W 0 is an initial weight of a polymer film prepared from the nitrile-based copolymer, and W 1 is a weight of the polymer film which is measured after storing the polymer film at 60° for 48 hours in an electrolyte solution,
wherein the positive electrode slurry composition has a solid content concentration of 70 wt % to 75 wt %,
wherein the nitrile-based copolymer has a weight-average molecular weight of 200,000 g/mol to 350,000 g/mol, and comprises 65 wt % to 75 wt % of a hydrogenated conjugated diene-derived unit and 25 wt % to 35 wt % of an α,β-unsaturated nitrile-derived unit,
wherein the nitrile-based copolymer is composed of a repeating unit represented by [Formula 1] and a repeating unit represented by [Formula 2],

and
wherein a resistance increase rate measured after storage of the secondary battery at 60° C. for 4 weeks is 20% or less.

2. The secondary battery of claim 1 , wherein the nitrile-based copolymer is a nitrile-based binary copolymer having the α,β-unsaturated nitrile-derived unit and the hydrogenated conjugated diene-derived unit.

3. The secondary battery of claim 2 , wherein the nitrile-based binary copolymer has a hydrogenation rate of the conjugated diene-derived unit of 90% or more.

4. The secondary battery of claim 1 , comprising:
96 parts by weight to 98.5 parts by weight of the positive electrode active material,
0.1 part by weight to 2 parts by weight of the carbon nanotubes,
1.2 parts by weight to 2 parts by weight of the binder, and
0.02 part by weight to 2 parts by weight of the nitrile-based copolymer based on 100 parts by weight of a total solid content in the positive electrode slurry composition.

5. The secondary battery of claim 1 , wherein the nitrile-based copolymer has the electrolyte solution swelling degree of 141% to 200%.

Assignees

• Lg Chemical Ltd
• Lg Energy Solution Ltd

Inventors

• Yoo Jung Woo
• Shim Hye Lim
• Lim Jun Muk

Classifications

• H01M2004/028

  Positive electrodes · CPC title

• H01M4/625

  Carbon or graphite · CPC title

• H01M10/052

  Li-accumulators · CPC title

• H01M4/622 Primary

  being polymers · CPC title

• H01M4/62

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