Development of Production Technology for Membrane-Electrode Assemblies With Radical Capturing Layer

This paper describes the development of mass-production technology for membrane-electrode assemblies (MEA) with a radical capturing layer and verifies its performance. Some of the authors of this paper previously developed an MEA with a radical capturing layer along the boundaries between the electrode catalyst layer and the polymer membrane to realize an endurance time of 20,000 h in accelerated daily start and daily stop (DSS) deterioration tests. Commercialization of these MEAs requires a production technology that suits mass production lines and provides reasonable cost performance. After developing a water-based slurry and selecting a gas diffusion layer (GDL), a catalyst layer forming technology uses a rotary screen method for electrode formation. Studies confirmed continuous formation of the catalyst layer, obtaining an anode/cathode thickness of 55 μm (+10/−20)/50 μm (+10/−20) by optimizing the opening ratio and thickness of the screen plate. A layer-forming technology developed for the radical capturing layer uses a two-fluid spraying method. Continuous formation of an 8-μm-thick (±3 μm) radical capturing layer proved feasible by determining the appropriate slurry viscosity, spray head selection, and optimization of spraying conditions.