Provided is a conductive material dispersion comprising single-walled carbon nanotubes, a dispersant, a dispersion aid, and a dispersion medium, wherein the dispersant comprises polyvinyl butyral and hydrogenated nitrile butadiene rubber, and the dispersion aid comprises a compound represented by Formula 1.
A-(R).sub.n[Formula 1] In Formula 1, A is a structure having a carbon number of 16 to 50 carbon number and comprising four or more aromatic rings and nitrogen, R is a structure comprising an anionic functional group, and n is an integer of 1 to 5.

A dielectric film includes an elastomer and nanoparticles dispersed in the elastomer while chemically bound to the elastomer. The nanoparticles have cyano groups and are manufactured by a sol-gel process using an organometallic compound. A method for manufacturing a dielectric film includes: producing a chelate compound of an organometallic compound; producing a sol of metallic oxide particles having cyano groups by adding a silane coupling agent having a cyano group, an organic solvent, and water to the chelate compound; preparing a mixed solution by mixing the sol of the metallic oxide particles having cyano groups and a polymer solution containing a rubber polymer having a functional group capable of reacting with a hydroxy group; and forming a dielectric film by applying the mixed solution to a substrate and by curing a coating film.

A composition for an electrochemical device contains a polymer that includes a nitrile group-containing monomer unit and either or both of a conjugated diene monomer unit and an alkylene structural unit and that has a structure derived from a specific compound on at least one terminal. The composition has a concentration of divalent or higher-valent metal ions of not less than 5 mass ppm and not more than 4,000 mass ppm.