Neutron Diffraction Study of a Sintered Iron Electrode In Operando
| Autor: | M.A. Thijs, Jeroen A. C. Nijman, Fokko M. Mulder, Bernhard M. H. Weninger, Lambert van Eijck |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Materials science
Passivation Hydrogen Neutron diffraction Inorganic chemistry Iron oxide chemistry.chemical_element engineering.material Feroxyhyte Article Surfaces Coatings and Films Electronic Optical and Magnetic Materials Metal chemistry.chemical_compound General Energy chemistry visual_art Electrode visual_art.visual_art_medium engineering Hydroxide Physical and Theoretical Chemistry |
| Zdroj: | The Journal of Physical Chemistry C, 125(30) The Journal of Physical Chemistry. C, Nanomaterials and Interfaces |
| ISSN: | 1932-7455 |
| Popis: | Iron is a promising, earth-abundant material for future energy applications. In this study, we use a neutron diffractometer to investigate the properties of an iron electrode in an alkaline environment. As neutrons penetrate deeply into materials, neutron scattering gives us a unique insight into what is happening inside the electrode. We made our measurements while the electrode was charging or discharging. Our key questions are: Which phases occur for the first and second discharge plateaus? And why are iron electrodes less responsive at higher discharge rates? We conclude that metallic iron and iron hydroxide form the redox pair for the first discharge plateau. For the second discharge plateau, we found a phase similar to feroxyhyte but with symmetrical and equally spaced arrangement of hydrogen atoms. The data suggest that no other iron oxide or iron (oxy)hydroxide formed. Remarkable findings include the following: (1) substantial amounts of iron hydroxide are always present inside the electrode. (2) Passivation is mostly caused by iron hydroxide that is unable to recharge. (3) Iron fractions change as expected, while iron hydroxide fractions are delayed, resulting in substantial amounts ofamorphous, undetectable iron phases. About 40% of the participating iron of the first plateau and about 55% of the participating iron for the second plateau are undetectable. (4) Massive and unexpected precipitation of iron hydroxide occurs in the transition from discharging to charging. (2), (3), and (4) together cause accumulation of iron hydroxide inside the electrode. |
| Databáze: | OpenAIRE |
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