Carbon nanotube dispersion liquid, method for preparing same, electrode slurry composition comprising same, electrode comprising same, and lithium secondary battery comprising same
The present specification relates to a carbon nanotube dispersion liquid, a method for preparing same, an electrode slurry composition comprising same, an electrode comprising same, and a lithium secondary battery comprising same, the carbon nanotube dispersion liquid comprising carbon nanotubes; a first dispersant having an amide group; and a second dispersant having an aromatic ring, wherein the viscosity at 25° C. and a shear rate of 15 sec −1 is 2,000 cPs or less.
1 . A carbon nanotube dispersion liquid comprising:
carbon nanotubes;
a first dispersant having an amide group;
a second dispersant having an aromatic ring and
an alkali metal salt;
wherein the dispersion liquid has a viscosity of 2,000 cPs or less at a temperature of 25° C. and a shear rate of 15 sec −1
wherein the first dispersant comprises a polyvinylpyrrolidone-based resin, and
wherein the first dispersant comprises a polyvinylpyrrolidone-based resin, and a molar ratio of the alkali metal salt based on 100 mol of a vinylpyrrolidone monomer contained in the polyvinylpyrrolidone-based resin is 60 mol or less.
2 . The dispersion liquid of claim 1 , wherein the first dispersant comprises one or more types selected from the group consisting of polyvinylpyrrolidone, polyesteramide, polycarboxylic acid amide, polyamidoamine, thioamido-amine, and a water-soluble nylon compound.
3 . The dispersion liquid of claim 1 , wherein the second dispersant has a hydroxyl group or a carboxyl group.
4 . The dispersion liquid of claim 1 , wherein the first and second dispersants are comprised in a weight ratio in a range of 1:10 to 10:1.
5 . The dispersion liquid of claim 1 , wherein the carbon nanotubes are single-walled carbon nanotubes (SWCNTs).
6 . The dispersion liquid of claim 1 , wherein the carbon nanotubes have a median particle size (D50) in a range of 0.1 μm to 20 μm.
7 . The dispersion liquid of claim 1 , wherein the carbon nanotubes are comprised in an amount in a range of 0.01 wt % to 10 wt % based on the total weight of the dispersion liquid.
8 . The dispersion liquid of claim 1 , wherein the dispersion liquid comprises an alkali metal element.
9 . The dispersion liquid of claim 1 , wherein the alkali metal salt is one or more selected from the group consisting of KOH, NaOH, LiOH, KOHH 2 O, NaOHH 2 O, LiOHH 2 O, K 2 CO 3 , Na 2 CO 3 , and LiCO 3 .
10 . The dispersion liquid of claim 1 , wherein a value expressed by Equation 1 is in a range of 2 to 10,
Shear
thinning
index
(
STI
)
=
V
l
o
w
/
V
h
i
g
h
[
Equation
1
]
where in Equation 1, V low is a viscosity of the dispersion liquid measured at a temperature of 25° C. and a shear rate of 15 sec −1 , and
V high is a viscosity of the dispersion liquid measured at a temperature of 25° C. and a shear rate of 150 sec −1 .
11 . The dispersion liquid of claim 1 , wherein a value calculated by Equation 2 is in a range of 1 to 5,
STI
D
50
/
μm
[
Equation
2
]
where in Equation 2, STI is a shear thinning index (STI) of the dispersion liquid, and
D50 is a median particle size (D50) of the carbon nanotubes.
12 . A method of preparing the dispersion liquid of claim 1 , the method comprising:
mixing carbon nanotubes, a first dispersant having an amide group, and a second dispersant having an aromatic ring.
13 . An electrode slurry composition comprising:
the dispersion liquid of claim 1 ;
an electrode active material; and
a binder.
14 . An electrode comprising an electrode active material layer formed by the electrode slurry composition of claim 13 .
15 . The electrode of claim 14 , wherein the electrode is a negative electrode.
16 . A lithium secondary battery comprising the electrode of claim 15 .