Effect of Superhydrophobic Catalyst Layers on PEMFC Durability

Abstract

High durability of proton exchange membrane fuel cells (PEMFCs) is one main objective of this technology nowadays. Among different ways, the use of a superhydrophobic catalyst layer in the cathode may help to increase the stability of the cell under operation. Superhydrophobic cathodic layers improve water management in the cell by enhancing the back-diffusion transport from cathode to anode. As a consequence, anode humidification is favored whereas flooding of the cathode is avoided, leading to higher cell response at intermediate and high current densities [1]. Superhydrophobic catalyst layers can be obtained by adding specific agents to the precursor ink that is later deposited together with the catalyst and the ionomer. Another possibility is the use of electrospray deposition, which does not require additives. Electrospray is a dry deposition method where the ink is deposited under an electric field, yielding particular ionomer distribution inside the pores of the layer as a consequence of electrostatic interactions.Accelerated stress tests (AST) are well stablished protocols to analyze durability of PEMFCs in a systematic and reduced time frame [2]. Protocols for stressing different components of the cell have been proposed. In this work, different cell configurations have been mounted, using electrosprayed catalyst layers in cathode, anode, and both. The cells have been submitted to an AST that affects mainly the cathodic catalyst layer. The study is complemented with microscopy analysis (cross-sectional) and local mechanical properties (small-punch) (Fig. 1).The results show the effect of superhydrophobic cathodic catalyst layers on the durability of a PEMFC.AcknowledgementsFunding by PORHYDRO2 project (TED2021-131620B-C22, ‘Preparation and characterisation of catalyst layers fabricated by electrospray for proton exchange fuel cells with passive gas feed’) by the Spanish Ministry of Science and Innovation.[1] M.A. Folgado, J.J. Conde, P. Ferreira-Aparicio, A.M. Chaparro, Single Cell Study of Water Transport in PEMFCs with Electrosprayed Catalyst Layers, Fuel Cells. 18 (2018) 602–612. https://doi.org/10.1002/fuce.201700217.[2] S. Stariha, N. Macauley, B.T. Sneed, D. Langlois, K.L. More, R. Mukundan, R.L. Borup, Recent Advances in Catalyst Accelerated Stress Tests for Polymer Electrolyte Membrane Fuel Cells, J. Electrochem. Soc. 165 (2018) F492–F501. https://doi.org/10.1149/2.0881807jes.[3] R. Hernández, S. Merino, D. Plaza, L. Duque, M.A. Folgado, A.M. Chaparro, M. Serrano, G. de Diego, Study of Mechanical Properties of Membrane-Electrode Assemblies for Proton Exchange Membrane Fuel Cells By the Small-Punch Technique, ECS Meet. Abstr. MA2022-02 (2022) 1426–1426. https://doi.org/10.1149/ma2022-02391426mtgabs. Figure 1