| 1. |
- Renman, Viktor, et al.
(author)
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Manganese Hexacyanomanganate as a Positive Electrode for Nonaqueous Li-, Na-, and K-Ion Batteries
- 2019
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In: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 123:36, s. 22040-22049
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Journal article (peer-reviewed)abstract
- K2Mn[Mn(CN)(6)] is synthesized, characterized, and evaluated as possible positive electrode material in nonaqueous Li-, Na-, and K-ion batteries. This compound belongs to the rich and versatile family of hexacyanometallates displaying distinctive structural properties, which makes it interesting for ion insertion purposes. It can be viewed as a perovskite-like compound in which CN-bridged Mn(CN)(6) octahedra form an open framework structure with sufficiently large diffusion channels able to accommodate a variety of insertion cations. By means of galvanostatic cycling and cyclic voltammetry tests in nonaqueous alkali metal half-cells, it is demonstrated that this material is able to reversibly host Li+, Na+, and K+ ions via electrochemical insertion/deinsertion within a wide voltage range. The general electrochemical features are similar for all of these three ion insertion chemistries. An in operando X-ray diffraction investigation indicates that the original monoclinic structure is transformed into a cubic one during charging (i.e., removal of cations from the host framework) and that such a process is reversible upon subsequent cell discharge and cation reuptake.
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| 2. |
- Hollmark, Håkan M., et al.
(author)
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Resonant Soft X-Ray Emission Spectroscopy and X-Ray Absorption Spectroscopy on the Cathode Material LiNi0.65Co0.25Mn0.1O2
- 2010
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In: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 157:8, s. A962-A966
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Journal article (peer-reviewed)abstract
- We present a study of the charge-state behavior of the Li-ion battery cathode material LixNi(0.65)Co(0.25)Mn(0.1)O(2) as observed by X-ray absorption spectroscopy (XAS) and resonant soft X-ray emission (RSXE). A set of six identical Li//LixNi0.65Co0.25Mn0.1O2 batteries has been cycled and is studied in different states of charge in the range of x = 1.0, ... ,0.2 before disassembly in an Ar glove box. Site and symmetry selective information about the electronic structure of the conduction and valence bands reveals that Ni as well as Co ions participate in the uptake and release of the extra electron charge that the inserted Li ions provide, but the Ni ion is much less than expected. The net amount of charge on the oxygen varies approximately 0.24 charge units in the range of x, and dramatic changes in the hybridization are evident in XAS and in particular in RSXE at the O K edge. We attribute this to a strong screening behavior of the Li ions between the oxide layers. Structural integrity effects limit the extraction of Li ions to a value of about x = 0.2-0.4. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3454739] All rights reserved.
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| 3. |
- Kam, Kinson C., et al.
(author)
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Synthesis and electrochemical properties of nanostructured Li(2)FeSiO(4)/C cathode material for Li-ion batteries
- 2011
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In: Solid State Ionics. - : Elsevier BV. - 0167-2738 .- 1872-7689. ; 192:1, s. 356-359
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Journal article (peer-reviewed)abstract
- Nanostructured Li(2)FeSiO(4)/C was synthesized by high-energy ball-milling and the amorphous citrate-assisted techniques. Similar redox behaviour is observed for samples prepared by the amorphous citrate-assisted route followed by a 4 h heat treatment: 0.3 V polarization and more sloping behaviour was observed when cycling between 2.0 V and 3.7 V at 60 degrees C; lower capacity fade is also observed compared to Li(2)FeSiO(4)/C prepared by the solid-state reaction technique. A discharge capacity of 102 mA h g(-1) is obtained for samples prepared by the high-energy ball-milling method, while capacities decrease from 95 to 77 mA h g(-1) using the amorphous citrate method for heat-treatment times increasing successively from 4 h to 18 h.
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| 4. |
- Ojwang, Dickson O., et al.
(author)
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Structure Characterization and Properties of K-Containing Copper Hexacyanoferrate
- 2016
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In: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 55:12, s. 5924-5934
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Journal article (peer-reviewed)abstract
- Copper hexacyanoferrate, Cu-II[Fe-III(CN)(6)](2/3)center dot nH(2)O, was synthesized, and varied amounts of IC ions were inserted via reduction by K2S2O3 (aq). Ideally, the reaction can be written as Cu-II[Fe-III(CN)(6)](2/3)-nH(2)O + 2x/3K(+) + 2x/3e(-)K(+) <-> K-2x/3 Cu-II[Fe-x(II).Fe-1-x(II),(CN)(6)](2/3)-nH(2)O. Infrared, Raman, and Mossbauer spectroscopy studies show that Fe-II is continuously reduced to Fell with increasing x, accompanied by a decrease of the a-axis of the cubic Fn (3) over barm unit cell. Elemental analysis of K by inductively coupled plasma shows that the insertion only begins when a significant fraction similar to 10% of the Fe-III, has already been reduced. Thermogravimetric analysis shows a fast exchange of water with ambient atmosphere and a total weight loss of similar to 26 wt % upon heating to 180 degrees C, above which the structure starts to decompose. The crystal structures of Cu-III[Fe-III(CN)(6)](2/3)center dot nH(2)O and K2/3Cu[Fe(CN)(6)](2/3)center dot nH(2)O were refined using synchrotron X-ray powder diffraction data. In both, one-third of the Fe(CN)(6) groups are vacant, and the octahedron around Cull is completed by water molecules. In the two structures, difference Fourier maps reveal three additional zeolitic water sites (8c, 32f, and 48g) in the center of the cavities formed by the-Cu-N-C-Fe- framework. The K-containing compound shows an increased electron density at two of these sites (32f and 48g), indicating them to be the preferred positions for the K+ ions.
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| 5. |
- Oltean, Gabriel, et al.
(author)
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Towards Li-ion batteries operating at 80 °C: Ionic liquid versus conventional liquid electrolytes
- 2018
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In: Batteries. - : MDPI AG. - 2313-0105. ; 4, s. 2-6
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Journal article (peer-reviewed)abstract
- Li-ion battery (LIB) full cells comprised of TiO2-nanotube (TiO2-nt) and LiFePO4 (LFP)electrodes and either a conventional organic solvent based liquid electrolyte or an ionic liquid basedelectrolyte have been cycled at 80 °C. While the cell containing the ionic liquid based electrolyteexhibited good capacity retention and rate capability during 100 cycles, rapid capacity fading was found for the corresponding cell with the organic electrolyte. Results obtained for TiO2-nt and LFP half-cells indicate an oxidative degradation of the organic electrolyte at 80 °C. In all, ionic liquidbased electrolytes can be used to significantly improve the performance of LIBs operating at 80 °C.
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| 6. |
- Renman, Viktor, et al.
(author)
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Structural-electrochemical relations in the aqueous copper hexacyanoferrate-zinc system examined by synchrotron X-ray diffraction
- 2017
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In: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 369, s. 146-153
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Journal article (peer-reviewed)abstract
- The storage process of Zn2+ in the Prussian blue analogue (PBA) copper hexacyanoferrate (Cu[Fe(CN)(6)](2/3)-nH(2) O-CuHCF) framework structure in a context of rechargeable aqueous batteries is examined by means of in operando synchrotron X-ray diffraction. Via sequential unit-cell parameter refinements of time-resolved diffraction data, it is revealed that the step-profile of the cell output voltage curves during repeated electrochemical insertion and removal of Zn2+ in the CuHCF host structure is associated with a non-linear contraction and expansion of the unit-cell in the range 0.36 < x < 1.32 for Znx/3Cu[Fe(CN)(6)](2/3)-nH(2)O. For a high insertion cation content there is no apparent change in the unit-cell contraction. Furthermore, a structural analysis with respect to the occupancies of possible Zn2+ sites suggests that the Fe(CN)(6) vacancies within the CuHCF framework play an important role in the structural-electrochemical behavior of this particular system. More specifically, it is observed that Zn2+ swaps position during electrochemical cycling, hopping between cavity sites to vacant ferricyanide sites.
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| 7. |
- Blidberg, Andreas, 1987-, et al.
(author)
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Electronic changes in poly(3,4-ethylenedioxythiophene)-coated LiFeSO4F during electrochemical lithium extraction
- 2019
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In: Journal of Power Sources. - : ELSEVIER SCIENCE BV. - 0378-7753 .- 1873-2755. ; 418, s. 84-89
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Journal article (peer-reviewed)abstract
- The redox activity of tavorite LiFeSO4F coated with poly (3,4-ethylenedioxythiophene), i.e. PEDOT, is investigated by means of several spectroscopic techniques. The electronic changes and iron-ligand redox features of this LiFeSO4F-PEDOT composite are probed upon delithiation through X-ray absorption spectroscopy. The PEDOT coating, which is necessary here to obtain enough electrical conductivity for the electrochemical reactions of LiFeSO4F to occur, is electrochemically stable within the voltage window employed for cell cycling. Although the electronic configuration of PEDOT shows also some changes in correspondence of its reduced and oxidized forms after electrochemical conditioning in Li half-cells, its p-type doping is fully retained between 2.7 and 4.1 V with respect to Li+/Li during the first few cycles. An increased iron-ligand interaction is observed in LixFeSO4F during electrochemical lithium extraction, which appears to be a general trend for polyanionic insertion compounds. This finding is crucial for a deeper understanding of a series of oxidation phenomena in Li-ion battery cathode materials and helps paving the way to the exploration of new energy storage materials with improved electrochemical performances.
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| 8. |
- Brant, William R., et al.
(author)
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In Operando X-ray and Neutron Diffraction for Lithium Ion Batteries
- 2017
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Other publication (other academic/artistic)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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| 9. |
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| 10. |
- Lindgren, Fredrik, et al.
(author)
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A hard X-ray photoelectron spectroscopy study on the solid electrolyte interphase of a lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide based electrolyte for Si-electrodes
- 2016
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In: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 301, s. 105-112
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Journal article (peer-reviewed)abstract
- This report focuses on the relatively new salt, lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide (LiTDI), and its functionality together with a silicon based composite electrode in a half-cell lithium ion battery context. LiTDI is a promising alternative to the commonly used LiPF6 salt because it does not form HF which can decompose the oxide layer on Si. The formation of a solid electrolyte interphase (SEI) as well as the development of the active Si-particles are investigated during the first electrochemical lithiation and de-lithiation. Characterizations are carried out at different state of charge with scanning electron microscopy (SEM) as well as hard x-ray photoelectron spectroscopy (HAXPES) at two different photon energies. This enables a depth resolved picture of the reaction processes and gives an idea of the chemical buildup of the SEI. The SEI is formed by solvent and LiTDI decomposition products and its composition is similar to SEI formed by other carbonate based electrolytes. The LiTDI salt or its decomposition products are not in itself reactive towards the active Si-material and no unwanted side reactions occurs with the active Si-particles. Despite some decomposition of the LiTDI salt, it is a promising alternative for electrolytes aimed towards Si-based electrodes.
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