METHOD FOR PRODUCING CATALYST INK

A method for producing a catalyst ink for fuel cells, wherein the method comprises obtaining the catalyst ink; wherein the catalyst ink comprises a catalyst, a carbon support, an ionomer, a solvent and a cation additive; wherein the catalyst is supported on the carbon support; wherein the carbon support is carbon support particles; wherein a particle size D90 of the carbon support particles in the catalyst ink is less than 3 μm; wherein, when a catalyst layer is formed by applying the catalyst ink to a substrate, a peel strength of the catalyst layer from the substrate is less than 3 N/m; and wherein a weight per unit area of the cation additive in the catalyst ink applied to the substrate, is 2.1 μg/cmor more and 3.3 μg/cmor less.