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- Brant, William R., et al.
(författare)
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In Operando X-ray and Neutron Diffraction for Lithium Ion Batteries
- 2017
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- To find new materials for lithium-ion batteries (LIBs) or to improve existing materials is a huge field of research. The positive electrode material in these devices is a bottleneck for increasing the energy density for the LIB and numerous oxides, phosphates, and silicates based on transition metals have been suggested. The crystallinity, chemical composition and structure of the bulk and the surface of a potential material are some important parameters influencing battery performance. In this presentation, we will show some examples of iron and Mn/Ni based cathode materials, and how in operando X-ray and neutron diffraction results have contributed to the understanding of how these materials function in batteries. In operando X-ray and neutron diffraction are extremely powerful techniques for investigating reaction mechanisms in battery materials in general. To date, the vast majority of these experiments have been performed using synchrotron X-ray diffraction, predominantly due to the fast data collection times possible. Is it so that synchrotron based X-ray diffraction always is the best choice? We will discuss this and show why in house in operando diffraction still is powerful. In operando neutron diffraction experiments are becoming increasingly popular due to a range of new cell designs increasing the accessibility of the technique [1], [2]. This presentation will discuss two different approaches to in operando neutron diffraction: a larger format wound cell and a cheaper modified a coin type cell. The wound cell design contains a large quantity of active material (up to 4 g) enabling high quality diffraction patterns to be collected down to small d-spacings. When used to investigate the positive electrode material LiMn1.5Ni0.5O4, reflections arising from Mn/Ni ordering could be observed to change during battery cycling. The modified coin cell design utilizes a completely different approach to in operando neutron diffraction experiments. The modified coin cells contain a large quantity of active material (~300-400 mg) to a much smaller amount of electrolyte (~10‑50 μL), separator and lithium metal. The smaller volume of electrolyte is particularly vital as it substantially reduces the cost of the experiment, as deuteration may no longer be necessary. The modified coin cell exhibited favourable electrochemistry when cycled at C/12 and enabled unit cell and phase fraction information to be extracted from in operando data collection conditions (5-15 min data sets). [1] M. Bianchini, E. Suard, L. Croguennec, C. Masquelier, J. Phys. Chem. C, 2014, 118, 25947. [2] R. Petibon, J. Li, N. Sharma, W.K. Pang, V.K. Peterson, J.R. Dahn, Electrochim. Acta, 2015, 174, 417.
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