Carbon corrosion fingerprint development and de-convolution of performance loss according to degradation mechanism in PEM fuel cells

Carbon corrosion and Pt dissolution are the two major catalyst layer degradation modes in polymer electrolyte membrane fuel cells (PEMFC). One of the challenges in employing accelerated stress tests (ASTs) in PEMFCs is to relate the performance loss under a given set of conditions to a specific life-limiting factor. No well-established method is available to de-convolute the contributions to performance loss arising from carbon corrosion and Pt dissolution. In this study, a method to overcome this deficiency is demonstrated for three membrane electrode assemblies (MEAs) with different cathode Pt loading levels between 0.25 and 0.5 mg cm−2 and structures through the use of various ASTs favoring carbon corrosion, Pt dissolution or mixed carbon corrosion-Pt dissolution modes. A diagnostic indicator or 'fingerprint' for the performance loss due to carbon corrosion in the cathode layer (CCL) is first obtained for each MEA. This fingerprint is then applied to the performance loss measured during the mixed mode AST to deconvolute the contribution from Pt dissolution. Finally, this estimate of the contribution from Pt dissolution is compared to the performance loss measured directly during the AST in which Pt dissolution is dominant. The effectiveness of this approach is examined and its limitations are discussed.