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Polymer Electrolyte Membrane (PEM) fuel cell seals durability
Polymer electrolyte membrane fuel cell (PEMFC) stacks require sealing around the perimeter of the cells to prevent the gases inside the cell from leaking. Elastomeric materials are commonly used for this purpose. The overall performance and durability of the fuel cell is heavily dependent on the lon...
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| Format: | Default Thesis |
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2016
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| Online Access: | https://hdl.handle.net/2134/21749 |
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| _version_ | 1818171906337013760 |
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| author | Sebnem Pehlivan-Davis |
| author_facet | Sebnem Pehlivan-Davis |
| author_sort | Sebnem Pehlivan-Davis (7124708) |
| collection | Figshare |
| description | Polymer electrolyte membrane fuel cell (PEMFC) stacks require sealing around the perimeter of the cells to prevent the gases inside the cell from leaking. Elastomeric materials are commonly used for this purpose. The overall performance and durability of the fuel cell is heavily dependent on the long-term stability of the gasket. In this study, the degradation of three elastomeric gasket materials (silicone rubber, commercial EPDM and a developed EPDM 2 compound) in an accelerated ageing environment was investigated. The change in properties and structure of a silicone rubber gasket caused by use in a real fuel cell was studied and compared to the changes in the same silicone rubber gasket material brought about by accelerated aging. The accelerated aging conditions were chosen to relate to the PEM fuel cell environment, but with more extreme conditions of elevated temperature (140°C) and greater acidity. Three accelerated ageing media were used. The first one was dilute sulphuric acid solution with the pH values of 1, 2 and 4. Secondly, Nafion ® membrane suspended in water was used for accelerated ageing at a pH 3 to 4. Finally, diluted trifluoroacetic acid (TFA) solution of pH 3.3 was chosen. Weight change and the tensile properties of the aged gasket samples were measured. In addition, compression set behaviour of the elastomeric seal materials was investigated in order to evaluate their potential sealing performance in PEM fuel cells. The results showed that acid hydrolysis was the most likely mechanism of silicone rubber degradation and that similar degradation occurred under both real fuel cell and accelerated aging conditions. The effect of TFA solution on silicone rubber was more aggressive than sulphuric acid and Nafion® solutions with the same acidity (pH value) suggesting that TFA accelerated the acid hydrolysis of silicone rubber. In addition, acid ageing in all three acidic solutions caused visible surface damage and a significant decrease in tensile strength of the silicone rubber material, but did not significantly affect the EPDM materials. EPDM 2 compound had a desirable (low) compression set value which was similar to silicone rubber and much better than the commercial EPDM. It also showed a very good performance in the fuel cell test rig conforming that it a potential replacement for silicone rubber in PEMFCs. |
| format | Default Thesis |
| id | rr-article-9232520 |
| institution | Loughborough University |
| publishDate | 2016 |
| record_format | Figshare |
| spelling | rr-article-92325202016-01-01T00:00:00Z Polymer Electrolyte Membrane (PEM) fuel cell seals durability Sebnem Pehlivan-Davis (7124708) Materials engineering not elsewhere classified Batteries and fuel cells Ageing Elastomers Rubber Materials Engineering not elsewhere classified Polymer electrolyte membrane fuel cell (PEMFC) stacks require sealing around the perimeter of the cells to prevent the gases inside the cell from leaking. Elastomeric materials are commonly used for this purpose. The overall performance and durability of the fuel cell is heavily dependent on the long-term stability of the gasket. In this study, the degradation of three elastomeric gasket materials (silicone rubber, commercial EPDM and a developed EPDM 2 compound) in an accelerated ageing environment was investigated. The change in properties and structure of a silicone rubber gasket caused by use in a real fuel cell was studied and compared to the changes in the same silicone rubber gasket material brought about by accelerated aging. The accelerated aging conditions were chosen to relate to the PEM fuel cell environment, but with more extreme conditions of elevated temperature (140°C) and greater acidity. Three accelerated ageing media were used. The first one was dilute sulphuric acid solution with the pH values of 1, 2 and 4. Secondly, Nafion ® membrane suspended in water was used for accelerated ageing at a pH 3 to 4. Finally, diluted trifluoroacetic acid (TFA) solution of pH 3.3 was chosen. Weight change and the tensile properties of the aged gasket samples were measured. In addition, compression set behaviour of the elastomeric seal materials was investigated in order to evaluate their potential sealing performance in PEM fuel cells. The results showed that acid hydrolysis was the most likely mechanism of silicone rubber degradation and that similar degradation occurred under both real fuel cell and accelerated aging conditions. The effect of TFA solution on silicone rubber was more aggressive than sulphuric acid and Nafion® solutions with the same acidity (pH value) suggesting that TFA accelerated the acid hydrolysis of silicone rubber. In addition, acid ageing in all three acidic solutions caused visible surface damage and a significant decrease in tensile strength of the silicone rubber material, but did not significantly affect the EPDM materials. EPDM 2 compound had a desirable (low) compression set value which was similar to silicone rubber and much better than the commercial EPDM. It also showed a very good performance in the fuel cell test rig conforming that it a potential replacement for silicone rubber in PEMFCs. 2016-01-01T00:00:00Z Text Thesis 2134/21749 https://figshare.com/articles/thesis/Polymer_Electrolyte_Membrane_PEM_fuel_cell_seals_durability/9232520 CC BY-NC-ND 4.0 |
| spellingShingle | Materials engineering not elsewhere classified Batteries and fuel cells Ageing Elastomers Rubber Materials Engineering not elsewhere classified Sebnem Pehlivan-Davis Polymer Electrolyte Membrane (PEM) fuel cell seals durability |
| title | Polymer Electrolyte Membrane (PEM) fuel cell seals durability |
| title_full | Polymer Electrolyte Membrane (PEM) fuel cell seals durability |
| title_fullStr | Polymer Electrolyte Membrane (PEM) fuel cell seals durability |
| title_full_unstemmed | Polymer Electrolyte Membrane (PEM) fuel cell seals durability |
| title_short | Polymer Electrolyte Membrane (PEM) fuel cell seals durability |
| title_sort | polymer electrolyte membrane (pem) fuel cell seals durability |
| topic | Materials engineering not elsewhere classified Batteries and fuel cells Ageing Elastomers Rubber Materials Engineering not elsewhere classified |
| url | https://hdl.handle.net/2134/21749 |