Yavuz, Murat (2016)
Investigation of Local and Average Structure in Li-ion Battery Electrode Materials by X-ray Diffraction.
Technische Universität Darmstadt
Ph.D. Thesis, Primary publication
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Item Type: | Ph.D. Thesis | ||||
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Type of entry: | Primary publication | ||||
Title: | Investigation of Local and Average Structure in Li-ion Battery Electrode Materials by X-ray Diffraction | ||||
Language: | English | ||||
Referees: | Donner, Prof. Dr. Wolfgang ; Ehrenberg, Prof.Dr. Helmut | ||||
Date: | 1 February 2016 | ||||
Place of Publication: | Darmstadt | ||||
Date of oral examination: | 11 December 2015 | ||||
Abstract: | In order to study structure and microstructure of crystalline materials, the powder diffraction method, which allows rapid and non-destructive analysis of multi-component mixtures is now one of the most widely used technique in many research fields. In this work, i) the instrument parameters of a Mo-Kα1 diffractometer, the P02.1 beamline at Petra III and the MSPD beamline at ALBA for both real and reciprocal space are determined. The real space resolution LaB6 in the PDF are 0.1977 Å, 0.1009 Å and 0.1193 Å for a Mo-Kα1 diffractometer, the P02.1 beamline at Petra III (SDD 200mm) and the MSPD beamline at ALBA, respectively. On the other hand, the angular resolution in the Rietveld refinement of LaB6 are 0.0666o, 0.0556o and 0.0281o. ii) the average and local structure of nanocrystalline Al0.57Sn0.43O1.71 anode material was investigated using conventional Rietveld refinement and X-ray Pair Distribution Function (PDF) technique. The crystallite sizes of both Al0.57Sn0.43O1.71 nanoparticles synthesized at 550oC and 40oC determined from the peak attenuation in the PDF refinement are about 20 Å, which are smaller in the Rietveld refinement due to the small size of the nanoparticles, which results in peak broadening. According to the weight-independent partial PDFs of cation-anion pairs for both samples, oxygen vacancies are located mostly around the Al atoms and cation-cation pairs for both samples illustrate a clustering of Al atoms. The volume changes during Li-Sn alloying/dealloying can be compensated by a large enough Li-Al-O matrix which may help to give better electrochemical performance. The best electrochemical cycling stability performance was obtained for the sample calcined at 550oC. iii) the electronic structure of LiMn2O4 was obtained using Rietveld refinement and PDF methods based on ex situ data, and the successful application of in situ total scattering experiments on LiMn2O4 was also shown. The results of the average structure analysis of LiMn2O4 sample obtained from the Rietveld refinement are in agreement with that of PDF, however in short distances they do not match very well due to the local distortion around the Mn ions. Because of that and to illustrate the electronic structure of ex situ PDF data RMC refinements were performed. As a result the average valence of the Mn ions is obtained to +3.72 and the structure has 0.56 mol of Mn3+. Additionally, in situ total scattering experiments were carried out on LiMn2O4, where background measurements were done and subtracted from the data of the active material. |
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URN: | urn:nbn:de:tuda-tuprints-52711 | ||||
Classification DDC: | 500 Science and mathematics > 500 Science 500 Science and mathematics > 530 Physics 500 Science and mathematics > 540 Chemistry |
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Divisions: | 11 Department of Materials and Earth Sciences > Material Science > Material Analytics 11 Department of Materials and Earth Sciences > Material Science > Materials Modelling 11 Department of Materials and Earth Sciences > Material Science > Structure Research |
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Date Deposited: | 04 Feb 2016 14:18 | ||||
Last Modified: | 09 Jul 2020 01:13 | ||||
URI: | https://tuprints.ulb.tu-darmstadt.de/id/eprint/5271 | ||||
PPN: | 377925756 | ||||
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