The Fraunhofer Institute for Solar Energy Systems (ISE) has made an advancement with electrolysers development of ultrafine microporous transport layers (PTL) using screen printing methods.
As the hydrogen market propulsion gains momentum, PEM electrolysers are at the forefront due to their capability to function under high current densities and compatibility with renewable energy sources. These properties make PEM technology indispensable for green hydrogen production. The role of PTLs is pivotal, acting essentially as the ‘lungs’ for catalyst-coated membranes. PTLs ensure the effective transport of water and gases which is crucial for the electrolyser’s performance. Stefan Bercher, a project leader at Fraunhofer ISE, emphasizes the cost-reduction potential by optimizing PTLs. Superior surface properties of these microporous layers (MPLs) are achieved through the utilization of fine porosity and reduced surface roughness, which further facilitate the use of lower iridium loadings in catalyst layers and enable thinner membranes, positively impacting the ohmic losses.
The research undertaken aims for precision in microstructural enhancements by adjusting the titan-based MPL to match the catalyst-coated layer precisely. With these metals being significant cost drivers, their optimal application is essential. Tom Smolinka, head of the department of Electrolysis and Hydrogen Infrastructure at Fraunhofer ISE, stresses that their extensive background in PEM components plays a critical role in tandem optimization of layers, deviating from traditional separated approaches.
Fraunhofer ISE leverages its established expertise in photovoltaics screen printing, allowing them to transfer this precision to the fabrication of ultrafine MPL structures. The project has conducted a thorough analysis of screen printing technology, capitalizing on its precise control over layer thickness and structure. Preliminary trials compared the performance of PTLs with these newly coated microporous layers against existing commercial variants. These trials involved meticulous optimization from ink formulation with titanium particles to the actual printing process and sintering technique, focusing on reducing surface roughness and enhancing performance metrics.
The results yielded significant improvements with the MPL layers featuring a thickness of approximately 20 µm, and a reduction in surface roughness by 46%. Stefan Bercher highlights the consequential improvement in catalyst contact, crucial for minimizing the Iridium content — a critical factor given its expense. This progression is vital for achieving Europe’s targets for material efficiency and market expansion amidst constrained resources.
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