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Identifying intermediaries in conversion-type lithium-ion battery anode materials with operando diffraction and operando magnetization measurements
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.ORCID iD: 0000-0002-4577-0792
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
Center for Energy Materials Research, Korea Institute of Science and Technology,.
Advanced Analysis Center, Korea Institute of Science and Technology.
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(English)Manuscript (preprint) (Other academic)
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:uu:diva-527111OAI: oai:DiVA.org:uu-527111DiVA, id: diva2:1853947
Available from: 2024-04-24 Created: 2024-04-24 Last updated: 2024-04-24
In thesis
1. Combining operando X-ray scattering and magnetometry to investigate conversion type electrode materials
Open this publication in new window or tab >>Combining operando X-ray scattering and magnetometry to investigate conversion type electrode materials
2024 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The transition towards a society with full electromobility depends heavily on the battery systems, which raises concerns about the environmental friendliness and sustainability of the current products on the market. Magnetite (Fe3O4) from the conversion type electrode family is one of the promising candidates in the search for a sustainable battery technology owing to its high theoretical storage capacity, high abundance, and low toxicity. However, the material suffers severely from capacity degradation in its practical use and hence requires better understanding and adjustments to reach its full potential.

Developing nanostructured electrode materials is one of the strategies to enhance its storage capacity, stability, and charging rate. Therefore, this thesis starts with synthesis and chemical lithiation of cubic (ferrimagnetic) Fe3O4 nanoparticles that are used as a model system to establish relationships between structural and magnetic properties upon lithiation. The thesis then explores the relationship between particle size, composition, crystal structure, and electrochemical performance of Fe3O4 electrodes via multi-operando techniques during cycles of lithiation and delithiation reactions. Magnetometry, known for its sensitivity to the chemical, compositional, and agglomeration state of the materials was exploited to measure the magnetic signal of the electrodes under operando conditions as a complement to operando SAXS and WAXS measurements. The results from the operando studies indicated that during electrochemi calcycling; LiFeO2, FeO and metallic iron (Fe) are produced as intermediate compounds, but their stability regions differ greatly when using nanoparticles or bulk materials and also when compared against ex-situ analyzed specimens. In addition, commercial micron- and nanosized (paramagnetic) Co3O4 particles were employed to study evolution of structural and magnetic properties over cycles to shed light on the size-dependent reaction kinetics. The obtained results revealed that nanosizing leads to improved electrochemical performance, variations in surface reaction kinetics, and differences in aging mechanisms. The magnetic measurements were crucial in determining surface capacitance reactions that involve gel-like polymeric layer growth and degradation during Li removal and uptake.

Lastly, the magnetic properties of layered NMC-based cathode materials were studied. The differences in their magnetic properties provided important information on the transition metal ordering depending on the choice of synthesis method that is used. Magnetization measurements were used in combination with diffraction data to choose an appropriate structure model to describe actual atomic arrangement in each material. Consequently, the findings in this thesis suggest that (operando) magnetometry can be employed as a complementary tool to elucidate structural details of battery electrodes, potentially revealing insights beyond the detection limits of volume-averaged X-ray scattering techniques.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2024. p. 70
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 2405
Keywords
Iron oxides, lithium ion batteries, conversion reaction, operando characterization, magnetometry, XRD, SAXS
National Category
Materials Engineering
Identifiers
urn:nbn:se:uu:diva-527112 (URN)978-91-513-2140-0 (ISBN)
Public defence
2024-06-14, Lecture hall Sonja Lyttkens, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:00 (English)
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Supervisors
Available from: 2024-05-21 Created: 2024-04-24 Last updated: 2024-05-21

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