Transport Property Requirements for Flow Battery Separators
Flow batteries are a promising technology for storing and discharging megawatt hours of electrical energy on the time scale of hours. The separator between the positive and negative electrodes strongly affects technical and economic performance. However, requirements for separators have not been rep...
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| Format: | Article |
| Language: | en_US |
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Electrochemical Society
2017
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| Online Access: | http://hdl.handle.net/1721.1/109805 https://orcid.org/0000-0002-2211-2164 https://orcid.org/0000-0002-7361-6637 |
| _version_ | 1826196656662511616 |
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| author | Darling, Robert Gallagher, Kevin Xie, Wei Su, Liang Brushett, Fikile R |
| author2 | Massachusetts Institute of Technology. Department of Chemical Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Chemical Engineering Darling, Robert Gallagher, Kevin Xie, Wei Su, Liang Brushett, Fikile R |
| author_sort | Darling, Robert |
| collection | MIT |
| description | Flow batteries are a promising technology for storing and discharging megawatt hours of electrical energy on the time scale of hours. The separator between the positive and negative electrodes strongly affects technical and economic performance. However, requirements for separators have not been reported in a general manner that enables quantitative evaluation of new systems such as nonaqueous flow batteries. This gap is addressed by deriving specifications for transport properties that are chemistry agnostic and align with aggressive capital cost targets. Three key transport characteristics are identified: area-specific resistance RΩ, crossover current density ix, and the coupling between crossover and capacity loss Ψ. Suggested maximum area-specific resistances are 0.29 and 2.3 Ω·cm[superscript 2] for aqueous and nonaqueous batteries, respectively. Allowable crossover rates are derived by considering the possible fates of active molecules that cross the separator and the coupling between Coulombic efficiency (CE) and capacity decline. The CE must exceed 99.992% when active species are unstable at the opposing electrode, while a CE of 97% can be tolerated when active molecules can be recovered from the opposing electrode. The contributions of diffusion, migration, and convection are discussed, quantified, and related to the physical properties of the separator and the active materials. |
| first_indexed | 2024-09-23T10:32:53Z |
| format | Article |
| id | mit-1721.1/109805 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T10:32:53Z |
| publishDate | 2017 |
| publisher | Electrochemical Society |
| record_format | dspace |
| spelling | mit-1721.1/1098052022-09-27T09:57:46Z Transport Property Requirements for Flow Battery Separators Darling, Robert Gallagher, Kevin Xie, Wei Su, Liang Brushett, Fikile R Massachusetts Institute of Technology. Department of Chemical Engineering Su, Liang Brushett, Fikile R Flow batteries are a promising technology for storing and discharging megawatt hours of electrical energy on the time scale of hours. The separator between the positive and negative electrodes strongly affects technical and economic performance. However, requirements for separators have not been reported in a general manner that enables quantitative evaluation of new systems such as nonaqueous flow batteries. This gap is addressed by deriving specifications for transport properties that are chemistry agnostic and align with aggressive capital cost targets. Three key transport characteristics are identified: area-specific resistance RΩ, crossover current density ix, and the coupling between crossover and capacity loss Ψ. Suggested maximum area-specific resistances are 0.29 and 2.3 Ω·cm[superscript 2] for aqueous and nonaqueous batteries, respectively. Allowable crossover rates are derived by considering the possible fates of active molecules that cross the separator and the coupling between Coulombic efficiency (CE) and capacity decline. The CE must exceed 99.992% when active species are unstable at the opposing electrode, while a CE of 97% can be tolerated when active molecules can be recovered from the opposing electrode. The contributions of diffusion, migration, and convection are discussed, quantified, and related to the physical properties of the separator and the active materials. United States. Department of Energy. Office of Basic Energy Sciences (Joint Center for Energy Storage Research) 2017-06-12T20:40:25Z 2017-06-12T20:40:25Z 2015-07 2015-07 Article http://purl.org/eprint/type/JournalArticle 0013-4651 1945-7111 http://hdl.handle.net/1721.1/109805 Darling, Robert et al. “Transport Property Requirements for Flow Battery Separators.” Journal of The Electrochemical Society 163.1 (2016): A5029–A5040. https://orcid.org/0000-0002-2211-2164 https://orcid.org/0000-0002-7361-6637 en_US http://dx.doi.org/10.1149/2.0051601jes Journal of The Electrochemical Society Creative Commons Attribution 4.0 International License http://creativecommons.org/licenses/by/4.0/ application/pdf Electrochemical Society Electrochemical Society |
| spellingShingle | Darling, Robert Gallagher, Kevin Xie, Wei Su, Liang Brushett, Fikile R Transport Property Requirements for Flow Battery Separators |
| title | Transport Property Requirements for Flow Battery Separators |
| title_full | Transport Property Requirements for Flow Battery Separators |
| title_fullStr | Transport Property Requirements for Flow Battery Separators |
| title_full_unstemmed | Transport Property Requirements for Flow Battery Separators |
| title_short | Transport Property Requirements for Flow Battery Separators |
| title_sort | transport property requirements for flow battery separators |
| url | http://hdl.handle.net/1721.1/109805 https://orcid.org/0000-0002-2211-2164 https://orcid.org/0000-0002-7361-6637 |
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