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Chowdhury A, Bird A, Liu J, Zenyuk IV, Kusoglu A, Radke CJ, Weber AZ. Linking Perfluorosulfonic Acid Ionomer Chemistry and High-Current Density Performance in Fuel-Cell Electrodes. ACS Appl Mater Interfaces 2021; 13:42579-42589. [PMID: 34490780 DOI: 10.1021/acsami.1c07611] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Transport phenomena are key in controlling the performance of electrochemical energy-conversion technologies and can be highly complex, involving multiple length scales and materials/phases. Material designs optimized for one reactant species transport however may inhibit other transport processes. We explore such trade-offs in the context of polymer-electrolyte fuel-cell electrodes, where ionomer thin films provide the necessary proton conductivity but retard oxygen transport to the Pt reaction site and cause interfacial resistance due to sulfonate/Pt interactions. We examine the electrode overall gas-transport resistance and its components as a function of ionomer content and chemistry. Low-equivalent-weight ionomers allow better dissolved-gas and proton transport due to greater water uptake and low crystallinity but also cause significant interfacial resistance due to the high density of sulfonic acid groups. These effects of equivalent weight are also observed via in situ ionic conductivity and CO displacement measurements. Of critical importance, the results are supported by ex situ ellipsometry and X-ray scattering of model thin-film systems, thereby providing direct linkages and applicability of model studies to probe complex heterogeneous structures. Structural and resultant performance changes in the electrode are shown to occur above a threshold sulfonic-group loading, highlighting the significance of ink-based interactions. Our findings and methodologies are applicable to a variety of solid-state energy-conversion devices and material designs.
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Affiliation(s)
- Anamika Chowdhury
- Energy Conversion Group, Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department of Chemical and Biomolecular Engineering, University of California Berkeley, Berkeley, California 94720, United States
| | - Ashley Bird
- Energy Conversion Group, Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department of Chemical and Biomolecular Engineering, University of California Berkeley, Berkeley, California 94720, United States
| | - Jiangjin Liu
- Energy Conversion Group, Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Iryna V Zenyuk
- Department of Chemical and Biomolecular Engineering, University of California Irvine, Irvine, California 92697, United States
| | - Ahmet Kusoglu
- Energy Conversion Group, Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Clayton J Radke
- Department of Chemical and Biomolecular Engineering, University of California Berkeley, Berkeley, California 94720, United States
| | - Adam Z Weber
- Energy Conversion Group, Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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