Electrode plate with a binder in a surface section with a lower glass transition point than a binder in a current collector plate section, secondary battery, and method for producing the electrode plate

A method for producing an electrode plate including:

• a current collector plate;
• and
• an active material layer formed on the current collector plate, the active material layer containing at least an active material and a binder,
• the binder including a plurality of binders having glass transition points Tg different from each other as the binder,
• provided that the active material layer is split into two portions in a middle in a thickness direction and that a portion forming a surface of the active material layer is referred to as a surface section and another portion contacting the current collector plate as a current collector plate section,
• a ratio (A2/A1) between an amount of the binder contained in the surface section (A2) and an amount of the binder contained in the current collector plate section (A1) being 1.0 to 1.2, and
• the binder contained in the surface section having an average glass transition point Tgu lower than an average glass transition point Tgd of the binder contained in the current collector plate section,
• wherein the method includes:
• a first coating step of coating a first active material paste containing a first coating binder consisting of at least one of the plurality of binders and having an average glass transition point Tga, and the active material, on the current collector plate to form a first coated film of the first active material paste on the current collector plate,
• a second coating step, after the first coating step, of coating a second active material paste containing a second coating binder consisting of at least another one of the plurality of binders and having an average glass transition point Tgb lower than the average glass transition point Tga of the first coating binder, and the active material, on the first coated film to form a second coated film of the second active material paste on the first coated film;
• and
• a drying step, after the second coating step, of drying the first coated film and the second coated film simultaneously to form the active material layer from the first coated film and the second coated film.