Abstract
Stress tests are developed that focus on anode catalyst layer degradation in proton exchange membrane electrolysis due to simulated start-stop operation. Ex situ testing indicates that repeated redox cycling accelerates catalyst dissolution, due to near-surface reduction and the higher dissolution kinetics of metals when cycling to high potentials. Similar results occur in situ, where a large decrease in cell kinetics (>70%) is found along with iridium migrating from the anode catalyst layer into the membrane. Additional processes are observed, however, including changes in iridium oxidation, the formation of thinner and denser catalyst layers, and platinum migration from the transport layer. Increased interfacial weakening is also found, adding to both ohmic and kinetic loss by adding contact resistances and isolating portions of the catalyst layer. Repeated shutoffs of the water flow further accelerate performance loss and increase the frequency of tearing and delamination at interfaces and within catalyst layers. These tests were applied to several commercial catalysts, where higher loss rates were observed for catalysts that contained ruthenium or high metal content. These results demonstrate the need to understand how operational stops occur, to identify how loss mechanisms are accelerated, and to develop strategies to limit performance loss.
Original language | English |
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Article number | 044503 |
Journal | Journal of the Electrochemical Society |
Volume | 171 |
Issue number | 4 |
DOIs | |
State | Published - Apr 1 2024 |
Funding
This work was authored by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. Funding provided by U.S. Department of Energy Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office through H2@Scale and the H2NEW Consortium. Electron microscopy research was supported by the Center for Nanophase Materials Sciences (CNMS), which is a U.S. Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory. The Talos F200X S/TEM tool was provided by U.S. DOE, Office of Nuclear Energy, Fuel Cycle R&D Program, and the Nuclear Science User Facilities. The X-ray absorption (MRCAT, 10-BM and 10-ID) and scattering (XSD, 9-ID-C) experiments were performed at the Advanced Photon Source (APS), a DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. The operation of MRCAT at the APS is supported by DOE and the MRCAT member institutions. The authors would like to thank Jan Ilavsky and Ivan Kuzmenko of the APS, 9-ID-C. This work was authored by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36\u201308GO28308. Funding provided by U.S. Department of Energy Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office through H2@Scale and the H2NEW Consortium. Electron microscopy research was supported by the Center for Nanophase Materials Sciences (CNMS), which is a U.S. Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory. The Talos F200X S/TEM tool was provided by U.S. DOE, Office of Nuclear Energy, Fuel Cycle R&D Program, and the Nuclear Science User Facilities. The X-ray absorption (MRCAT, 10-BM and 10-ID) and scattering (XSD, 9-ID-C) experiments were performed at the Advanced Photon Source (APS), a DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02\u201306CH11357. The operation of MRCAT at the APS is supported by DOE and the MRCAT member institutions. The authors would like to thank Jan Ilavsky and Ivan Kuzmenko of the APS, 9-ID-C.
Keywords
- electrode kinetics
- electrolysis
- energy conversion