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Accelerated Electrochemical Decomposition of Li2O2 under X-ray Illumination
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.ORCID iD: 0000-0003-2538-8104
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
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2013 (English)In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 4, no 23, 4045-4050 p.Article in journal (Refereed) Published
Abstract [en]

This work presents the first report detailing the effect of X-rays on the electrochemical decomposition of Li2O2, which is the main reaction during the charging process in a Li-O-2 battery. An operando synchrotron radiation powder X-ray diffraction (SR-PXD) experiment was performed. The results indicate that the electrochemical decomposition of Li2O2 is dramatically accelerated under X-ray irradiation. The accelerated decomposition of Li2O2 follows a zero-order reaction, and the decomposition rate constant is proportional to the intensity of X-ray used. A mechanism for the electrochemical decomposition of Li2O2 under X-ray irradiation is proposed. These results give an insight into the charging process in Li-O-2 batteries.

Place, publisher, year, edition, pages
2013. Vol. 4, no 23, 4045-4050 p.
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:uu:diva-214019DOI: 10.1021/jz402230sISI: 000328101000005OAI: oai:DiVA.org:uu-214019DiVA: diva2:684252
Available from: 2014-01-07 Created: 2014-01-07 Last updated: 2017-12-06Bibliographically approved
In thesis
1. The O2 electrode performance in the Li-O2 battery
Open this publication in new window or tab >>The O2 electrode performance in the Li-O2 battery
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Li-O2 batteries have been attracting increasing attention and R&D efforts as promising power sources for electric vehicles (EVs) due to their significantly higher theoretical energy densities compared to conventional Li-ion batteries. The research presented in this thesis covers the investigation of factors influencing the decomposition of Li2O2, the development of highly active electrocatalysts, and the design of low-cost and easy-operation binder-free O2 electrodes for Li-O2 batteries. Being the main technique, SR-PXD was used both as a continuous light source to advance the electrochemical decomposition of Li2O2 under the X-ray illumination and an operando tool that allowed us to probe the degradation of Li2O2.

Since XRD was intensively used in my thesis work, the effect of X-ray irradiation on the stability of Li2O2 was studied. The accelerating effect of X-rays on the electrochemical decomposition of Li2O2 was, for the first time, explored. The electrochemical decomposition rate of Li2O2 was proportional to the X-ray intensity used. It is proposed that the decomposition might involve a three-step reaction with [Li2O2]x+ and Li2-xO2* as intermediates, which followed pseudo-zero-order kinetics. Then, three electrocatalysts (Pt/MNT, Ru/MNT and Li2C8H2O6) were developed, which exhibited good electrocatalytic performances during the OER. Their activities were evaluated by following the Li2O2 decomposition in electrodes during the charging processes. In addition, the time-resolved OER kinetics for the electrocatalyst-containing Li-O2 cells charged galvanostatically and potentiostatically was systematically investigated using operando SR-PXD. It was found that a small amount of Pt or Ru decoration on the MNTs enhanced the OER efficiency in a Li-O2 cell. The Li2O2 decomposition of an electrode with 5 wt% Pt/MNT, 2 wt% Ru/MNT or Li2C8H2O6 in a Li-O2 cell followed pseudo-zero-order kinetics. Finally, a novel binder-free NCPE for Li-O2 batteries was presented. It displayed a bird’s nest microstructure, which could provide the self-standing electrode with considerable mechanic durability, fast O2 diffusion and enough space for the discharge product deposition. The NCPE contained N-containing functional groups, which may promote the electrochemical reactions.

Place, publisher, year, edition, pages
Uppsala: Uppsala universitet, 2015. 73 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1271
Keyword
Li-oxygen battery, X-ray irradiation, Electrocatalyst, Synchrotron radiation powder X-ray diffraction, Time-resolved kinetics, Binder-free cathode, Bird’s nest microstructure.
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-259589 (URN)978-91-554-9294-6 (ISBN)
Public defence
2015-09-25, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2015-09-03 Created: 2015-08-09 Last updated: 2016-04-21

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Liu, JiaYounesi, RezaDahbi, MohammedEdström, KristinaGustafsson, TorbjörnZhu, Jiefang

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