US 12,424,670 B2
Positive electrode slurry composition for secondary battery, and positive electrode for secondary battery and secondary battery which are prepared by using the same
Jung Woo Yoo, Daejeon (KR); Hye Lim Shim, Daejeon (KR); and Jun Muk Lim, Daejeon (KR)
Assigned to LG Energy Solution, Ltd., Seoul (KR)
Filed by LG Chem, Ltd., Seoul (KR)
Filed on Mar. 4, 2020, as Appl. No. 16/809,075.
Application 16/809,075 is a continuation of application No. PCT/KR2018/014526, filed on Nov. 23, 2018.
Claims priority of application No. 10-2017-0158628 (KR), filed on Nov. 24, 2017; and application No. 10-2017-0158629 (KR), filed on Nov. 24, 2017.
Prior Publication US 2020/0203778 A1, Jun. 25, 2020
Int. Cl. H01M 4/139 (2010.01); H01M 4/62 (2006.01); H01M 10/42 (2006.01); H01M 4/02 (2006.01)
CPC H01M 10/4235 (2013.01) [H01M 4/625 (2013.01); H01M 2004/028 (2013.01)] 5 Claims
OG exemplary drawing
 
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 m2/g to 190 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:
electrolyte solution swelling degree (%)={(W1−W0)/W0}×100  Equation (1):
wherein, in Equation (1), 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,
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],

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