artience Co., Ltd.

Provided is a carbon nanotube dispersed liquid which contains carbon nanotubes, a dispersant, and a solvent, and in which, in a volume-based particle size distribution curve measured by a laser diffraction/scattering-type particle size distribution measuring method, particle size distribution peaks are present in a particle size range of 0.1-3 μm and in a particle size range of 10-100 μm, and the cumulative particle size D 50 is 4 μm or more.

A carbon nanotube dispersion including a carbon nanotube, a solvent, and a dispersant. A highly conductive electrode membrane can be produced as a result of the carbon nanotube using a carbon nanotube dispersion satisfying (1), (2), and (3). (1) An average outer diameter is more than 3 nm and less than 10 nm. (2) A peak is present in a powder X-ray diffraction analysis at a diffraction angle of 2θ=25°±2°, and a half value width of the peak is 3° to 6°. (3) When a maximum peak intensity within the range of 1,560 to 1,600 cm −1 in a Raman spectrum is G and a maximum peak intensity within the range of 1,310 to 1,350 cm −1 is D, a G/D ratio is 0.5 to 4.5.

A carbon nanotube dispersion contains a solvent and bundle-type carbon nanotubes formed from carbon nanotubes having an average diameter of 3 nm to 30 nm, a proportion of the number of bundle-type carbon nanotubes each in a shape having an outer diameter of 50 nm to 5 μm and a fiber length of 1 μm to 100 μm being 0.2% or more based on the number of carbon nanotubes each having an outer diameter of 10 nm or more in the carbon nanotube dispersion.

Provided is a carbon nanotube dispersion composition including carbon nanotubes, a dispersant, and a solvent and satisfying (1) and (2) as follows: (1) an average outer diameter of the carbon nanotubes calculated from an SEM image obtained by observing the carbon nanotubes included in the carbon nanotube dispersion composition is 15 nm or more and 50 nm or less; and (2) when a target pixel group in the SEM image obtained by observing the carbon nanotubes included in the carbon nanotube dispersion composition is set as the carbon nanotubes, and a value obtained by dividing an absolute maximum length by a length of a free curve, that is, a skeleton length, is set as linearity, a proportion of carbon nanotubes with a linearity of 0.9 or more among carbon nanotubes with a skeleton length of 1 μm or more is 40% or more and 90% or less.

Provided is a conductive material dispersion including: a conductive material containing at least one kind selected from the group consisting of a carbon nanotube and carbon black; carboxymethyl cellulose or its salt; and water. The carboxymethyl cellulose or its salt has a weight average molecular weight of 10,000 to 150,000 and an etherification degree of 0.5 to 0.9. A product of the complex elastic modulus (Pa) and the phase angle (°) of the conductive material dispersion is 100 or more and 1,500 or less.

Provided is a carbon nanotube dispersion composition including carbon nanotubes, a dispersant, and a solvent and satisfying (1) and (2) as follows: (1) an average outer diameter of the carbon nanotubes calculated from an SEM image obtained by observing the carbon nanotubes included in the carbon nanotube dispersion composition is 15 nm or more and 50 nm or less; and (2) when a target pixel group in the SEM image obtained by observing the carbon nanotubes included in the carbon nanotube dispersion composition is set as the carbon nanotubes, and a value obtained by dividing an absolute maximum length by a length of a free curve, that is, a skeleton length, is set as linearity, a proportion of carbon nanotubes with a linearity of 0.9 or more among carbon nanotubes with a skeleton length of 1 μm or more is 40% or more and 90% or less.

A slurry for positive electrode film, including a lithium iron phosphate-based positive electrode active material, a dispersant, a binder resin, and a solvent, and the dispersant including a copolymer (A) having a nitrile group-containing structural unit and a structural unit derived from a conjugated diene in which unsaturated bonds are partially hydrogenated and a mass ratio of residual double bond (RDB) calculated by formula (1) satisfies 0.05 to 5 mass %: RDB (mass %)=(BD/(BD+HBD))×100 (1) (where BD is a mass ratio of a structural unit derived from a conjugated diene having unsaturated bond based on a total mass of a structural unit derived from a conjugated diene, and HBD is a mass ratio of a structural unit derived from a conjugated diene in which an unsaturated bond is hydrogenated to a total mass of a structural unit derived from a conjugated diene).

A method for evaluating a conductive material for use in a rechargeable battery is provided. The rechargeable battery includes an electrode plate in which a mixture layer, containing an active material and the conductive material, is formed on a substrate. The method includes preparing a paste containing simulated primary particles and the conductive material. The simulated primary particles are formed of an insulative material that simulates the active material of the rechargeable battery. The method further includes applying the prepared paste to a simulated substrate that simulates the substrate of the rechargeable battery, drying the applied paste to prepare a test coating containing the simulated primary particles, and measuring a coating resistance R S (Ω·cm) to evaluate the conductive material. The coating resistance corresponds to a surface resistance of the test coating.

A manufacturing method of a carbon nanotube dispersion liquid containing carbon nanotubes, a dispersant, and a solvent includes at least the following steps. A dispersion treatment is performed on the carbon nanotubes having a BET specific surface area (m 2 /g) of 220 to 800, 20 parts by mass to 100 parts by mass of the dispersant relative to 100 parts by mass of the carbon nanotube, and the solvent using a homogenizer or a paint conditioner. A fiber length of the carbon nanotubes in the carbon nanotube dispersion liquid obtained from the dispersion treatment ranges from 0.8 μm to 3.5 μm.

Carbon nanotubes have a bulk density X of 0.095 g/cm 3 or more and 0.125 g/cm 3 or less, a Zr content of 5 ppm or more and 500 ppm or less, and a maximum solvent absorption capacity Y of carbon nanotubes defined by formula (5) below of 8.0 or more, Y = W / V forumla ⁢ ( 5 ) (in formula (5), V is a mass (g) of carbon nanotubes, and W is a maximum mass (g) of N-methyl-2-pyrrolidone absorbed by carbon nanotubes when N-methyl-2-pyrrolidone is added dropwise to V (g) of carbon nanotubes in a 25° C. environment).