Development of Catalyst Ink for Crack-Free Catalyst Coated Membrane Based on Direct Coating of Proton Exchange Membrane Fuel Cells

The article explores the various types of solvents and the water content of the ink. It also considers whether dispersion is requisite, the size and weight of zirconia balls during dispersion, the influence of ball milling time and speed on the quality of the catalyst layer, and the determination of the solvent system consisting of n-propanol, 80% water content, and 1 micrometer (µm) zirconia balls, with two equivalents. A formula and method are devised with a rotating speed of 2000 revolutions per minute (rpm) and a duration of 20 min, respectively, to create a crack-free catalyst layer. Through an investigation of the effect of the ionomer content in the formula on performance, it is clarified that a closer bond between the catalyst layer and the proton exchange membrane emerges. This is because the ionomer in the ink shares the same molecular structure with the membrane. Consequently, the catalyst layer becomes more porous, reducing the mass transfer resistance and ohmic resistance under standard operating conditions, resulting in a performance of [email protected]/cm² for direct coating. However, it also leads to a reduction of the ionomer on the side of the catalyst layer away from the proton exchange membrane.