Functional sample of 5x5 cm2 catalyst coated membrane prepared by spiral rod printing on Nafion membrane
Abstract
The Mayer rod, also known as a spiral stretching ruler, is a film applicator used to apply a defined thickness of liquid layer. The thickness of the prepared layer can be in the range 4-500 μm. This technique is suitable for low viscosity inks, which is advantageous for catalytic layers. To verify the suitability and quality of the print of catalyst coated membranes (CCM), a deposition apparatus was designed and manufactured with an "endless" running belt driven by a motor, where the speed could be adjusted by a frequency converter. This equipment simulated real "per roll" printing. Many optimization steps were taken to improve the quality of deposited ink, such as varying rod wire diameter, ink composition, and using different solvents, etc. Deposited ink layers were studied by scanning electron microscopy. An optimized Pt and IrOx-based catalytic inks prepared by spiral rod printing on Nafion membrane were tested in fuel cell and electrolyzer. The IrOx layers were investigated in terms of power density in a water electrolyzer of the PEMWE type with an active area of membrane electrode assembly 5x5 cm, which can also be used as a reversible fuel cell. The production results of 0.15 l H2/min @ 25 cm2 at 20 A current and 1.7 V cell voltage representing a result compared to commercial MEAs.
It was shown that spiral rode printing is a good, reliable and cost-effective solution for CCM printing compared to the more expensive slot die printing that is commonly used.