Influence of binder content in silver based gas diffusion electrodes on pore system and electrochemical performance
| Autor: | Thomas Turek, André Hilger, David Franzen, Ingo Manke, Markus Osenberg, Barbara Ellendorff, Melanie Paulisch |
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| Rok vydání: | 2019 |
| Předmět: |
Tafel equation
Materials science Polytetrafluoroethylene Scanning electron microscope General Chemical Engineering article 02 engineering and technology Electrolyte 010402 general chemistry 021001 nanoscience & nanotechnology Electrochemistry 01 natural sciences Focused ion beam 0104 chemical sciences chemistry.chemical_compound Oxygen reduction reaction Gas diffusion electrode Chlor alkali electrolysis Oxygen depolarized cathode chemistry Chemical engineering Electrode ddc:540 Materials Chemistry Gaseous diffusion 0210 nano-technology |
| Popis: | The influences of the polytetrafluoroethylene PTFE content in silver based gas diffusion electrodes on the resulting physical properties and the electrochemical performance during oxygen reduction in concentrated sodium hydroxide electrolyte were investigated through half cell measurements. A systematic variation of the pore system was achieved by application of different silver PTFE ratios during the production of the gas diffusion electrodes GDE . In all electrodes, a silver skeleton structure with relatively constant properties was formed, while the PTFE fills up part of the open pore space. The resulting structures were characterized with a variety of methods for the physical properties supported by focused ion beam milling and scanning electron microscope FIB SEM tomography. It could be shown that variations in the obtained pore system strongly influence the electrochemical performance of the electrodes. Determination of the Tafel slopes revealed that this is not due to changes in the electrocatalytic activity but rather caused by variations in the electrolyte uptake. While too small amounts of PTFE 1 wt lead to decreased performance through electrolyte flooding, higher PTFE contents above about 5 wt also deteriorate the electrode performance because the extent of the three phase boundary diminishes. The decisive role of the electrolyte intrusion was confirmed by measurements at higher electrolyte pressure. While the best electrochemical performance was achieved with an electrode containing 98 wt silver, a slightly higher PTFE content is advisable to prevent breakthrough of the electrolyte |
| Databáze: | OpenAIRE |
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