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  1. Article: Use of Nano Seed Crystals To Control Peroxide Morphology in a Nonaqueous Li–O2 Battery

    Ganapathy, Swapna / Li Zhaolong / Anastasaki Maria S / Basak Shibabrata / Miao Xue-Fei / Goubitz Kees / Zandbergen HennyW / Mulder Fokko M / Wagemaker Marnix

    The Journal of Physical Chemistry C. 2016 Aug. 25, v. 120, no. 33

    2016  

    Abstract: The high theoretical energy density of Li–O₂ batteries as required for electrification of transport has pushed Li–O₂ research to the forefront. The poor cyclability of this system due to incomplete Li₂O₂ oxidation is one of the major hurdles to be ... ...

    Abstract The high theoretical energy density of Li–O₂ batteries as required for electrification of transport has pushed Li–O₂ research to the forefront. The poor cyclability of this system due to incomplete Li₂O₂ oxidation is one of the major hurdles to be crossed if it is ever to deliver a high reversible energy density. Here we present the use of nano seed crystallites to control the size and morphology of the Li₂O₂ crystals. The evolution of the Li₂O₂ lattice parameters during operando X-ray diffraction demonstrates that the hexagonal NiO nanoparticles added to the activated carbon electrode act as seed crystals for equiaxed growth of Li₂O₂, which is confirmed by scanning electron microscopy energy-dispersive X-ray spectroscopy (SEM-EDX) elemental maps also showing preferential formation of Li₂O₂ on the NiO surface. Even small amounts of NiO (∼5 wt %) particles act as preferential sites for Li₂O₂ nucleation, effectively reducing the average size of the primary Li₂O₂ crystallites and promoting crystalline growth. This is supported by first principle calculations, which predict a low interfacial energy for the formation of NiO–Li₂O₂ interfaces. The eventual cell failure appears to be the consequence of electrolyte side reactions, indicating the necessity of more stable electrolytes. The demonstrated control of the Li₂O₂ crystallite growth by the rational selection of appropriate nano seed crystals appears to be a promising strategy to improve the reversibility of Li–air electrodes.
    Keywords X-ray diffraction ; activated carbon ; batteries ; carbon electrodes ; crystallites ; electrolytes ; energy ; energy density ; energy-dispersive X-ray analysis ; nanoparticles ; nickel oxide ; oxidation ; physical chemistry ; scanning electron microscopy
    Language English
    Dates of publication 2016-0825
    Size p. 18421-18427.
    Publishing place American Chemical Society
    Document type Article
    ISSN 1932-7455
    DOI 10.1021%2Facs.jpcc.6b04732
    Database NAL-Catalogue (AGRICOLA)

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  2. Article ; Online: Nature of Li2O2 oxidation in a Li-O2 battery revealed by operando X-ray diffraction.

    Ganapathy, Swapna / Adams, Brian D / Stenou, Georgiana / Anastasaki, Maria S / Goubitz, Kees / Miao, Xue-Fei / Nazar, Linda F / Wagemaker, Marnix

    Journal of the American Chemical Society

    2014  Volume 136, Issue 46, Page(s) 16335–16344

    Abstract: Fundamental research into the Li-O2 battery system has gone into high gear, gaining momentum because of its very high theoretical specific energy. Much progress has been made toward understanding the discharge mechanism, but the mechanism of the oxygen ... ...

    Abstract Fundamental research into the Li-O2 battery system has gone into high gear, gaining momentum because of its very high theoretical specific energy. Much progress has been made toward understanding the discharge mechanism, but the mechanism of the oxygen evolution reaction (OER) on charge (i.e., oxidation) remains less understood. Here, using operando X-ray diffraction, we show that oxidation of electrochemically generated Li2O2 occurs in two stages, but in one step for bulk crystalline (commercial) Li2O2, revealing a fundamental difference in the OER process depending on the nature of the peroxide. For electrochemically generated Li2O2, oxidation proceeds first through a noncrystalline lithium peroxide component, followed at higher potential by the crystalline peroxide via a Li deficient solid solution (Li(2-x)O2) phase. Anisotropic broadening of the X-ray Li2O2 reflections confirms a platelet crystallite shape. On the basis of the evolution of the broadening during charge, we speculate that the toroid particles are deconstructed one platelet at a time, starting with the smallest sizes that expose more peroxide surface. In the case of in situ charged bulk crystalline Li2O2, the Li vacancies preferentially form on the interlayer position (Li1), which is supported by first-principle calculations and consistent with their lower energy compared to those located next to oxygen (Li2). The small actively oxidizing fraction results in a gradual reduction of the Li2O2 crystallites. The fundamental insight gained in the OER charge mechanism and its relation to the nature of the Li2O2 particles is essential for the design of future electrodes with lower overpotentials, one of the key challenges for high performance Li-air batteries.
    Language English
    Publishing date 2014-11-05
    Publishing country United States
    Document type Journal Article
    ZDB-ID 3155-0
    ISSN 1520-5126 ; 0002-7863
    ISSN (online) 1520-5126
    ISSN 0002-7863
    DOI 10.1021/ja508794r
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Bonn / Germany

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    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

  3. Article: Nature of Li2O2 Oxidation in a Li–O2 Battery Revealed by Operando X-ray Diffraction

    Ganapathy, Swapna / Adams Brian D / Anastasaki Maria S / Goubitz Kees / Miao Xue-Fei / Nazar Linda F / Stenou Georgiana / Wagemaker Marnix

    Journal of the American Chemical Society. 2014 Nov. 19, v. 136, no. 46

    2014  

    Abstract: Fundamental research into the Li–O₂ battery system has gone into high gear, gaining momentum because of its very high theoretical specific energy. Much progress has been made toward understanding the discharge mechanism, but the mechanism of the ... ...

    Abstract Fundamental research into the Li–O₂ battery system has gone into high gear, gaining momentum because of its very high theoretical specific energy. Much progress has been made toward understanding the discharge mechanism, but the mechanism of the oxygen evolution reaction (OER) on charge (i.e., oxidation) remains less understood. Here, using operando X-ray diffraction, we show that oxidation of electrochemically generated Li₂O₂ occurs in two stages, but in one step for bulk crystalline (commercial) Li₂O₂, revealing a fundamental difference in the OER process depending on the nature of the peroxide. For electrochemically generated Li₂O₂, oxidation proceeds first through a noncrystalline lithium peroxide component, followed at higher potential by the crystalline peroxide via a Li deficient solid solution (Li₂–ₓO₂) phase. Anisotropic broadening of the X-ray Li₂O₂ reflections confirms a platelet crystallite shape. On the basis of the evolution of the broadening during charge, we speculate that the toroid particles are deconstructed one platelet at a time, starting with the smallest sizes that expose more peroxide surface. In the case of in situ charged bulk crystalline Li₂O₂, the Li vacancies preferentially form on the interlayer position (Li1), which is supported by first-principle calculations and consistent with their lower energy compared to those located next to oxygen (Li2). The small actively oxidizing fraction results in a gradual reduction of the Li₂O₂ crystallites. The fundamental insight gained in the OER charge mechanism and its relation to the nature of the Li₂O₂ particles is essential for the design of future electrodes with lower overpotentials, one of the key challenges for high performance Li–air batteries.
    Keywords batteries ; crystallites ; electrochemistry ; energy ; oxidation ; oxygen ; oxygen production ; specific energy ; X-radiation ; X-ray diffraction
    Language English
    Dates of publication 2014-1119
    Size p. 16335-16344.
    Publishing place American Chemical Society
    Document type Article
    ZDB-ID 3155-0
    ISSN 1520-5126 ; 0002-7863
    ISSN (online) 1520-5126
    ISSN 0002-7863
    DOI 10.1021%2Fja508794r
    Database NAL-Catalogue (AGRICOLA)

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    Kategorien

    In stock of ZB MED Bonn / Germany

    Z 4' 55/32: Show issues
    Z 7.3: Show issues

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

    Inter-library loan at ZB MED

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  4. Article ; Online: Operando Nanobeam Diffraction to Follow the Decomposition of Individual Li2O2 Grains in a Nonaqueous Li-O2 Battery.

    Ganapathy, Swapna / Heringa, Jouke R / Anastasaki, Maria S / Adams, Brian D / van Hulzen, Martijn / Basak, Shibabrata / Li, Zhaolong / Wright, Jonathan P / Nazar, Linda F / van Dijk, Niels H / Wagemaker, Marnix

    The journal of physical chemistry letters

    2016  Volume 7, Issue 17, Page(s) 3388–3394

    Abstract: Intense interest in the Li-O2 battery system over the past 5 years has led to a much better understanding of the various chemical processes involved in the functioning of this battery system. However, detailed decomposition of the nanostructured Li2O2 ... ...

    Abstract Intense interest in the Li-O2 battery system over the past 5 years has led to a much better understanding of the various chemical processes involved in the functioning of this battery system. However, detailed decomposition of the nanostructured Li2O2 product, held at least partially responsible for the limited reversibility and poor rate performance, is hard to measure operando under realistic electrochemical conditions. Here, we report operando nanobeam X-ray diffraction experiments that enable monitoring of the decomposition of individual Li2O2 grains in a working Li-O2 battery. Platelet-shaped crystallites with aspect ratios between 2.2 and 5.5 decompose preferentially via the more reactive (001) facets. The slow and concurrent decomposition of individual Li2O2 crystallites indicates that the Li2O2 decomposition rate limits the charge time of these Li-O2 batteries, highlighting the importance of using redox mediators in solution to charge Li-O2 batteries.
    Language English
    Publishing date 2016-08-16
    Publishing country United States
    Document type Journal Article
    ISSN 1948-7185
    ISSN (online) 1948-7185
    DOI 10.1021/acs.jpclett.6b01368
    Database MEDical Literature Analysis and Retrieval System OnLINE

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