Controlling the ionic polymer/gas interface property of a PEM fuel cell catalyst layer during membrane electrode assembl
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RESEARCH ARTICLE
Controlling the ionic polymer/gas interface property of a PEM fuel cell catalyst layer during membrane electrode assembly fabrication Regis P. Dowd Jr.1 · Yuanchao Li1 · Trung Van Nguyen1 Received: 27 August 2019 / Accepted: 19 June 2020 © Springer Nature B.V. 2020
Abstract During high current density operation, water production in the polymer electrolyte membrane fuel cell (PEMFC) cathode catalyst layer can negatively affect performance by lowering mass transport of oxygen into the cathode. In this paper, a novel heat treatment process for controlling the ionic polymer/gas interface property of the fuel cell catalyst layer is investigated and then incorporated into the membrane electrode assembly (MEA) fabrication process. XPS characterization of the catalyst layer’s ionomer-gas interface at its outer surface and its sublayers’ surfaces obtained by scraping off successive layers of the catalyst layers confirms that a hydrophobic ionomer interface can be achieved across the catalyst layer using a specific heat treatment condition. Based on the results of the catalyst layer study, the MEA fabrication process is modified to identify heat treatment configuration and conditions that will create an optimal hydrophobic ionomer-gas interface inside the cathode catalyst layer. Finally, fuel cell tests conducted on the conventional and new MEAs under different operating temperatures show the performance of the fuel cells with the treated MEAs was > 130% higher than that with the conventional MEA at 25 °C and 70 °C with humidified air and > 45% higher at 70 °C with dry air. The durability of the hydrophobic treatment on the cathode catalyst layer ionomer is also confirmed by the accelerated stress test. Graphic abstract PEMFC Catalyst Layer with Hydrophobic Ionomer/Gas Interface
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10800-020-01453-w) contains supplementary material, which is available to authorized users. Extended author information available on the last page of the article
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Vol.:(0123456789)
Journal of Applied Electrochemistry
Keywords PEM fuel cells · Catalyst layer · Ionic polymer/gas interface
1 Introduction The cathode catalyst layer of a polymer electrolyte membrane fuel cell (PEMFC) exhibits high water saturation levels (i.e. flooding conditions) during high current density operations. Water flooding of the cathode results in reduced fuel cell performance due to lower mass transport rate of oxygen to the catalyst reaction site. Various advances have been developed to overcome water management issues related to PEMFCs. A few of these advances include the development of the interdigitated flow field [1], integration of hydrophobic PTFE nanoparticles into the catalyst layer [2, 3], and gas diffusion layer fabrication with various types of non-wetting materials [4, 5], each of these advances led to improved mass transport performance during high current density operations. The PEMFC catalyst layer is comprised of three phases: an
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