Advances in pinhole detection on electrolysis and fuel cell membranes through lock-in thermography with pulsed reactive excitation

Abstract

Gas crossover through membrane defects such as pinholes in polymer-electrolyte membranes compromises efficiency, durability and safety in electrolyzers and fuel cells. This work introduces hydrogen-excitation lock-in thermography (H2-LIT), which is based on the modulation of the hydrogen concentration beneath catalyst-coated membrane samples. The novel defect detection method is validated by individual laser-drilled pinholes. H2-LIT amplitude images show discrete spots at the pinhole positions with a lateral resolution of 0.5mm. The smallest verified pinholes with an opening diameter of 7μm are clearly detected. Compared to the well-known reactive excitation infrared-thermography, H2-LIT improves spatial resolution and sensitivity while reducing ambient drift. The method enables high-resolution pinhole mapping, which is essential as a prerequisite for microstructural defect characterization and root-cause analysis.