Title: Anode-Design Strategies for Improved Performance of Polymer-Electrolyte Fuel Cells with Ultra-Thin Electrodes

Abstract

We report results of systematic, holistic, diagnostic, and cell studies to elucidate the mechanistic role of the experimentally determined influence of the anode gas-diffusion layer (GDL) on the performance of ultra-thin electrode polymer-electrolyte fuel cells, which can further enable fuel-cell market penetration. Measurements of product water balance and in situ neutron imaging of operational membrane-electrode-assembly water profiles demonstrate how improved performance is due to a novel anode GDL fiber-density modulated structure at the micrometer scale that removes water preferentially out of the anode, a key strategy to manage water in these cells. The banded structure results in low transport-resistance pathways, which affect water-droplet removal from the GDL surface. This interfacial effect is unexpectedly shown to be critical for decreasing overall water holdup throughout the cell. These studies demonstrate a new material paradigm for understanding and controlling fuel-cell water management and related high-power technologies or electrodes where multiphase flow occurs. Very thin electrodes enable high power density in electrochemical technologies, yet their thinness engenders issues related to buildup of products (e.g., water in polymer-electrolyte fuel cells [PEFCs]). The article explores an unexpected materials solution to the problem, which highlights the need to study such complicated systems in a holistic manner ofmore » a complete cell due to the nonlinearities existent in the highly coupled physical phenomena. The improved performance is due to an inherent unintentional manufacturing heterogeneity in the cell backing layer, which mainly affects its surface properties. With this knowledge, one can now engineer and optimize these critical heterogeneities for different architectures. The findings are relevant to those working on materials for electrochemical energy conversion and represent new key knowledge that can have significant impact in PEFCs and related electrochemical cells, especially where multiphase flow occurs. High-power electrodes in electrochemical technologies (e.g., fuel cells) typically require ultra-thin catalyst layers, which, especially when multiphase flow exists, exhibit mass-transport limitations. These have been mitigated through new backing layer structures and nontraditional removal of water out of the anode side of the cell for a new design and operation paradigm.« less

Authors:

Steinbach, Andrew J.; Allen, Jeffrey S.; Borup, Rodney L.; Hussey, Daniel S.; Jacobson, David L.; Komlev, Andrei; Kwong, Anthony; MacDonald, James; Mukundan, Rangachary; Pejsa, Matt J.; Roos, Michael; Santamaria, Anthony D.; Sieracki, James M.; Spernjak, Dusan; Zenyuk, Iryna V.; Weber, Adam Z.

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Publication Date:

Sun Jul 01 00:00:00 EDT 2018

Research Org.:

Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States). Center for Neutron Research

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Sustainable Transportation Office. Hydrogen Fuel Cell Technologies Office (HFTO); Dept. of Commerce (United States)

OSTI Identifier:

1564422

Alternate Identifier(s):

OSTI ID: 1477693; OSTI ID: 1601647

Report Number(s):

LA-UR-17-28090
Journal ID: ISSN 2542-4351; S2542435118301375; PII: S2542435118301375

Grant/Contract Number:  

AC02-05CH11231; AI01-01EE50660; AC52-06NA25396

Resource Type:

Published Article

Journal Name:

Joule

Additional Journal Information:

Journal Name: Joule Journal Volume: 2 Journal Issue: 7; Journal ID: ISSN 2542-4351

Publisher:

Elsevier - Cell Press

Country of Publication:

United States

Language:

English

Subject:

25 ENERGY STORAGE; fuel cells; ultra-thin electrodes; water management; transport phenomena; material design; heterogeneous substrate; gas diffusion layer; neutron radiography; x-ray computed tomography