Carbon material dispersion and use thereof

A carbon material dispersion comprising:

• at least two carbon materials selected from the group consisting of single-walled carbon nanotubes, multi-walled carbon nanotubes, and carbon black;
• an aqueous medium;
• a dispersant;
• and
• a binder resin, wherein
• the carbon material dispersion satisfies the following requirements (1) and (2),
• surface resistivity a (Ω/sq) of a first film formed by applying and drying the carbon material dispersion, the first film containing 3% by mass of the carbon materials and having a thickness of 1 μm and surface resistivity b (Ω/sq) of a second film formed by applying and drying a control dispersion having the same composition as the carbon material dispersion except that one of the carbon materials is not contained, the second film containing 3% by mass of the carbon material or carbon materials and having a thickness of 1 μm satisfy a relationship of a<b, and
• the surface resistivity a is 5.0×105 Ω/sq or less:
• (1) when the carbon materials are composed of a combination of a single-walled carbon nanotube and carbon black, the amount of carbon black based on 1 part by mass of the single-walled carbon nanotube is 0.001 to 0.43 parts by mass,
• when the carbon materials are composed of a combination of a multi-walled carbon nanotube and carbon black, the amount of carbon black based on 1 part by mass of the multi-walled carbon nanotube is 0.001 to 0.43 parts by mass,
• when the carbon materials are composed of a combination of a single-walled carbon nanotube and a multi-walled carbon nanotube, the amount of the multi-walled carbon nanotube based on 1 part by mass of the single-walled carbon nanotube is 10 to 100 parts by mass, or
• when the carbon materials are composed of a combination of a single-walled carbon nanotube, a multi-walled carbon nanotube, and carbon black, the amount of carbon black based on 1 part by mass of the total amount of the single-walled carbon nanotube and the multi-walled carbon nanotube is 0.001 to 0.43 parts by mass, and the amount of the multi-walled carbon nanotube based on 1 part by mass of the single-walled carbon nanotube is 10 to 100 parts by mass;
• (2) the surface resistivity of the dry film containing 3% by mass of the carbon materials and having a thickness of 1 μm is 1.0×106 Ω/sq or less.