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Epp V, Wilkening M. Li-ion Dynamics in Solids as Seen Via Relaxation NMR. HANDBOOK OF SOLID STATE BATTERIES 2015. [DOI: 10.1142/9789814651905_0005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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Wohlmuth D, Epp V, Wilkening M. Fast Li ion dynamics in the solid electrolyte Li7 P3 S11 as probed by (6,7) Li NMR spin-lattice relaxation. Chemphyschem 2015; 16:2582-93. [PMID: 26192263 DOI: 10.1002/cphc.201500321] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Indexed: 11/12/2022]
Abstract
The development of safe and long-lasting all-solid-state batteries with high energy density requires a thorough characterization of ion dynamics in solid electrolytes. Commonly, conductivity spectroscopy is used to study ion transport; much less frequently, however, atomic-scale methods such as nuclear magnetic resonance (NMR) are employed. Here, we studied long-range as well as short-range Li ion dynamics in the glass-ceramic Li7 P3 S11 . Li(+) diffusivity was probed by using a combination of different NMR techniques; the results are compared with those obtained from electrical conductivity measurements. Our NMR relaxometry data clearly reveal a very high Li(+) diffusivity, which is reflected in a so-called diffusion-induced (6) Li NMR spin-lattice relaxation peak showing up at temperatures as low as 313 K. At this temperature, the mean residence time between two successful Li jumps is in the order of 3×10(8) s(-1) , which corresponds to a Li(+) ion conductivity in the order of 10(-4) to 10(-3) S cm(-1) . Such a value is in perfect agreement with expectations for the crystalline but metastable glass ceramic Li7 P3 S11 . In contrast to conductivity measurements, NMR analysis reveals a range of activation energies with values ranging from 0.17 to 0.26 eV, characterizing Li diffusivity in the bulk. In our case, through-going Li ion transport, when probed by using macroscopic conductivity spectroscopy, however, seems to be influenced by blocking grain boundaries including, for example, amorphous regions surrounding the Li7 P3 S11 crystallites. As a result of this, long-range ion transport as seen by impedance spectroscopy is governed by an activation energy of approximately 0.38 eV. The findings emphasize how surface and grain boundary effects can drastically affect long-range ionic conduction. If we are to succeed in solid-state battery technology, such effects have to be brought under control by, for example, sophisticated densification or through the preparation of samples that are free of any amorphous regions that block fast ion transport.
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Brandstätter H, Wohlmuth D, Bottke P, Pregartner V, Wilkening M. Li Ion Dynamics in Nanocrystalline and Structurally Disordered Li2TiO3. Z PHYS CHEM 2015. [DOI: 10.1515/zpch-2014-0665] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
The monoclinic polymorph of Li2TiO3 (β-form) is known
to be a relatively poor Li ion conductor. Up to now, no
information is available on how the ion transport properties change
when going from well-ordered crystalline Li2TiO3 to
a structurally disordered form with the same chemical
composition. Here, we used high-energy ball milling to prepare
nanocrystalline, defect-rich Li2TiO3; ion dynamics have been
studied via impedance spectroscopy. It turned out that ball
milling offers the possibility to enhance long-range ion transport in
the oxide by approximately 3 orders of magnitude. Its effect on the
oxide ceramic is two-fold: besides the introduction of a large number
of defects, the originally μm-sized crystallites are
decreased to crystallites with a mean diameter of less than
50 nm. This process is accompanied by a mechanically
induced phase transformation towards the α-form of
Li2TiO3; besides that, a significant amount of amorphous
materials is produced during milling. Structural disorder in
nanocrystalline as well as amorphous Li2TiO3 is anticipated
to play the capital role in governing Li ion dynamics of the
sample finally obtained.
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Preishuber-Pflügl F, Bottke P, Pregartner V, Bitschnau B, Wilkening M. Correlated fluorine diffusion and ionic conduction in the nanocrystalline F(-) solid electrolyte Ba(0.6)La(0.4)F(2.4)-(19)F T1(ρ) NMR relaxation vs. conductivity measurements. Phys Chem Chem Phys 2015; 16:9580-90. [PMID: 24728404 DOI: 10.1039/c4cp00422a] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Chemical reactions induced by mechanical treatment may give access to new compounds whose properties are governed by chemical metastability, defects introduced and the size effects present. Their interplay may lead to nanocrystalline ceramics with enhanced transport properties being useful to act as solid electrolytes. Here, the introduction of large amounts of La into the cubic structure of BaF2 served as such an example. The ion transport properties in terms of dc-conductivity values of the F(-) anion conductor Ba1-xLaxF2+x (here with x = 0.4) considerably exceed those of pure, nanocrystalline BaF2. So far, there is only little knowledge about activation energies and jump rates of the elementary hopping processes. Here, we took advantage of both impedance spectroscopy and (19)F NMR relaxometry to get to the bottom of ion jump diffusion proceeding on short-range and long-range length scales in Ba0.6La0.4F2.4. While macroscopic transport is governed by an activation energy of 0.55 to 0.59 eV, the elementary steps of hopping seen by NMR are characterised by much smaller activation energies. Fortunately, we were able to deduce an F(-) self-diffusion coefficient by the application of spin-locking NMR relaxometry.
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Stanje B, Epp V, Nakhal S, Lerch M, Wilkening M. Li ion dynamics along the inner surfaces of layer-structured 2H-LixNbS2. ACS APPLIED MATERIALS & INTERFACES 2015; 7:4089-99. [PMID: 25633906 DOI: 10.1021/am5078655] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Layer-structured materials, such as graphite (LiCy) or Lix(Co,Ni,Mn)O2, are important electrode materials in current battery research that still relies on insertion materials. This is due to their excellent ability to reversibly accommodate small alkali ions such as Li(+) and Na(+). Despite of these applications, microscopic information on Li ion self-diffusion in transition metal sulfides are relatively rare. Here, we used (7)Li nuclear magnetic resonance (NMR) spectroscopy to study translational Li ion diffusion in hexagonal (2H) LixNbS2 (x = 0.3, 0.7, and 1) by means of variable-temperature NMR relaxometry. (7)Li spin-lattice relaxation rates and (7)Li NMR spectra were used to determine Li jump rates and activation barriers as a function of Li content. Hereby, NMR spin-lattice relaxation rates recorded with the spin-lock technique offered the possibility to study Li ion dynamics on both the short-range and long-range length scale. Information was extracted from complete diffusion-induced rate peaks that are obtained when the relaxation rate is plotted vs inverse temperature. The peak maximum of the three samples studied shifts toward higher temperatures with increasing Li content x in 2H-LixNbS2. Information on the dimensionality of the diffusion process was experimentally obtained by frequency dependent Rρ measurements carried out at T = 444 K, that is in the high-temperature regime of the rate peaks. A slight, but measurable frequency-dependence within this limit is found for all samples; it is in good agreement with predictions from relaxation models developed to approximate low-dimensional (2D) jump diffusion.
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Fabián M, Bottke P, Girman V, Düvel A, Da Silva KL, Wilkening M, Hahn H, Heitjans P, Šepelák V. A simple and straightforward mechanochemical synthesis of the far-from-equilibrium zinc aluminate, ZnAl2O4, and its response to thermal treatment. RSC Adv 2015. [DOI: 10.1039/c5ra09098a] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Far-from-equilibrium nanostructured ZnAl2O4 is prepared via simple and straightforward mechanochemical synthesis. Upon heating above 1100 K, mechanosynthesized ZnAl2O4 relaxes towards a structural state that is similar to the bulk one.
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32
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Epp V, Ma Q, Hammer EM, Tietz F, Wilkening M. Very fast bulk Li ion diffusivity in crystalline Li1.5Al0.5Ti1.5(PO4)3 as seen using NMR relaxometry. Phys Chem Chem Phys 2015; 17:32115-21. [DOI: 10.1039/c5cp05337d] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
7Li NMR spin-lock relaxometry reveals the elementary activation barriers, EA, the ions have to jump over in LATP-based fast lithium-ion conductors.
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Preishuber-Pflügl F, Epp V, Nakhal S, Lerch M, Wilkening M. Defect-enhanced F-
ion conductivity in layer-structured nanocrystalline BaSnF4
prepared by high-energy ball milling combined with soft annealing. ACTA ACUST UNITED AC 2014. [DOI: 10.1002/pssc.201400193] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Aigner D, Freunberger S, Wilkening M, Saf R, Borisov SM, Klimant I. Enhancing photoinduced electron transfer efficiency of fluorescent pH-probes with halogenated phenols. Anal Chem 2014; 86:9293-300. [PMID: 25126834 PMCID: PMC4165219 DOI: 10.1021/ac502513g] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 08/15/2014] [Indexed: 01/20/2023]
Abstract
Photoinduced electron transfer (PET), which causes pH-dependent quenching of fluorescent dyes, is more effectively introduced by phenolic groups than by amino groups which have been much more commonly used so far. That is demonstrated by fluorescence measurements involving several classes of fluorophores. Electrochemical measurements show that PET in several amino-modified dyes is thermodynamically favorable, even though it was not experimentally found, underlining the importance of kinetic aspects to the process. Consequently, the attachment of phenolic groups allows for fast and simple preparation of a wide selection of fluorescent pH-probes with tailor-made spectral properties, sensitive ranges, and individual advantages, so that a large number of applications can be realized. Fluorophores carrying phenolic groups may also be used for sensing analytes other than pH or molecular switching and signaling.
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Pichler J, Torvisco A, Bottke P, Wilkening M, Uhlig F. Novel amino propyl substituted organo tin compounds. CAN J CHEM 2014. [DOI: 10.1139/cjc-2013-0504] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this work, a new synthetic pathway yielding unprotected amino propyl tin compounds is described. For this purpose, mono stannanes with different substitution patterns are used. In a first step, tin hydrides are deprotonated using lithium diisopropyl amide and mixed with an electrophile containing a protected amine in the ω-position. After deprotection via acidic hydrolysis, the desired amino propyl tin compounds are obtained in high yield and purity. The thermal reaction behavior of the amino propyl tin hydrohalide intermediates containing one aromatic residue at the central tin atom is also investigated. For this purpose, amino propyl tin hydrohalides are heated under vacuum until the aromatic hydrocarbon is liberated. This thermal treatment leads to so far unknown tin halides containing an amino propyl side chain. For all of these substances detailed liquid 1H, 13C, and 119Sn-nuclear magnetic resonance (NMR) data were obtained, and in one case solid state NMR is also conducted. Regarding solids, single crystal X-ray analysis is performed. Some derivatization reactions with these new substances are demonstrated, especially the synthesis of an amino propyl tin carboxylate, which might be very interesting for biological, pharmaceutical, or technical processes.
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Rettenwander D, Blaha P, Laskowski R, Schwarz K, Bottke P, Wilkening M, Geiger C, Amthauer G. DFT Study of the Role of Al 3+ in the Fast Ion-Conductor Li 7-3x Al 3+x La 3Zr 2O 12 Garnet. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2014; 26:2617-2623. [PMID: 25673921 PMCID: PMC4311941 DOI: 10.1021/cm5000999] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 03/13/2014] [Indexed: 05/25/2023]
Abstract
We investigate theoretically the site occupancy of Al3+ in the fast-ion-conducting cubic-garnet Li7-3x Al3+x La3Zr2O12 (Ia-3d) using density functional theory. By comparing calculated and measured 27Al NMR chemical shifts an analysis shows that Al3+ prefers the tetrahedrally coordinated 24d site and a distorted 4-fold coordinated 96h site. The site energies for Al3+ ions, which are slightly displaced from the exact crystallographic sites (i.e., 24d and 96h), are similar leading to a distribution of slightly different local oxygen coordination environments. Thus, broad 27Al NMR resonances result reflecting the distribution of different isotropic chemical shifts and quadrupole coupling constants. From an energetic point of view, there is evidence that Al3+ could also occupy the 48g site with its almost regular octahedral coordination sphere. Although this has been reported by neutron powder diffraction, the NMR chemical shift calculated for such an Al3+ site has not been observed experimentally.
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Šepelák V, Düvel A, Wilkening M, Becker KD, Heitjans P. Mechanochemical reactions and syntheses of oxides. Chem Soc Rev 2014; 42:7507-20. [PMID: 23364473 DOI: 10.1039/c2cs35462d] [Citation(s) in RCA: 145] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Technological and scientific challenges coupled with environmental considerations have prompted a search for simple and energy-efficient syntheses and processing routes of materials. This tutorial review provides an overview of recent research efforts in non-conventional reactions and syntheses of oxides induced by mechanical action. It starts with a brief account of the history of mechanochemistry. Ensuing discussions will review the progress in homogeneous and heterogeneous mechanochemical reactions in oxides of various structures. The review demonstrates that the event of mechanically induced reactions provides novel opportunities for the non-thermal manipulation of materials and for the tailoring of their properties.
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38
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Marczewski MJ, Stanje B, Hanzu I, Wilkening M, Johansson P. “Ionic liquids-in-salt” – a promising electrolyte concept for high-temperature lithium batteries? Phys Chem Chem Phys 2014; 16:12341-9. [DOI: 10.1039/c4cp01133c] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel electrolyte concept, “ionic liquid-in-salt”, is presented here through the proof-of-concept system (1 − x)EMIMTFSI–(x)LiTFSI, 0.66 ≤ x ≤ 0.97.
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Preishuber-Pflügl F, Wilkening M. Evidence of low dimensional ion transport in mechanosynthesized nanocrystalline BaMgF4. Dalton Trans 2014; 43:9901-8. [DOI: 10.1039/c4dt00904e] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The ternary fluoride BaMgF4 is mechanically synthesized and shows anisotropic F dynamics even in its nanocrystalline form.
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40
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Bottke P, Ren Y, Hanzu I, Bruce PG, Wilkening M. Li ion dynamics in TiO2anode materials with an ordered hierarchical pore structure – insights from ex situ NMR. Phys Chem Chem Phys 2014; 16:1894-901. [DOI: 10.1039/c3cp54586e] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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41
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Epp V, Wilkening M. Motion of Li+in Nanoengineered LiBH4and LiBH4:Al2O3Comparison with the Microcrystalline Form. Chemphyschem 2013; 14:3706-13. [DOI: 10.1002/cphc.201300743] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Indexed: 11/08/2022]
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42
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Epp V, Nakhal S, Lerch M, Wilkening M. Two-dimensional diffusion in Li0.7NbS2 as directly probed by frequency-dependent 7Li NMR. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:195402. [PMID: 23604197 DOI: 10.1088/0953-8984/25/19/195402] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Li ion diffusion in layer-structured Li0.7NbS2 has been complementary investigated by nuclear magnetic resonance (NMR) spectroscopy from an atomic scale point of view. In the present case, (7)Li NMR spin-lattice relaxation (SLR) rates R1ρ probed in the rotating frame of reference proved very informative in characterizing the Li self-diffusion process in the van der Waals gap between the NbS2 layers. While temperature-variable SLRρ measurements were used to determine dynamic parameters such as jump rates (τ(-1)) and the activation energy (Ea), frequency-dependent measurements were used to specify the dimensionality of the diffusion process. In particular, the effect of annealing, i.e., the distribution of Li ions between the layers, on overall Li dynamics has been studied. When plotted in an Arrhenius diagram, the R1ρ rates of an annealed sample, which were recorded at a locking frequency of 20 kHz, pass through a diffusion-induced relaxation peak whose maximum shows up at 320 K. Employing an appropriate diffusion model and appropriately accounting for a non-diffusive background relaxation, a Li jump rate τ(-1)(300 K) ≈ 1.3 × 10(5) s(-1) and an activation energy Ea of 0.43(2) eV can be deduced. Most importantly, in the high-T limit of the diffusion-induced rate peak, i.e., when ω1τ << 1 holds, the rates follow a logarithmic frequency dependence. This points to a diffusion process of low dimensionality and is in good agreement with predictions of relaxation models developed for 2D diffusion.
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43
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Rosciano F, Pescarmona PP, Houthoofd K, Persoons A, Bottke P, Wilkening M. Towards a lattice-matching solid-state battery: synthesis of a new class of lithium-ion conductors with the spinel structure. Phys Chem Chem Phys 2013; 15:6107-12. [PMID: 23503337 DOI: 10.1039/c3cp50803j] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Lithium ion batteries have conquered most of the portable electronics market and are now on the verge of deployment in large scale applications. To be competitive in the automotive and stationary sectors, however, they must be improved in the fields of safety and energy density (W h L(-1)). Solid-state batteries with a ceramic electrolyte offer the necessary advantages to significantly improve the current state-of-the-art technology. The major limit towards realizing a practical solid-state lithium-ion battery lies in the lack of viable ceramic ionic conductors. Only a few candidate materials are available, each carrying a difficult balance between advantages and drawbacks. Here we introduce a new class of possible solid-state lithium-ion conductors with the spinel structure. Such compounds could be coupled with spinel-type electrode materials to obtain a "lattice matching" solid device where low interfacial resistance could be achieved. Powders were prepared by wet chemistry, their structure was studied by means of diffraction techniques and magic angle spinning NMR, and Li(+) self-diffusion was estimated by static NMR line shape measurements. Profound differences in the Li(+) diffusion properties were observed depending on the composition, lithium content and cationic distribution. Local Li(+) hopping in the spinel materials is accompanied by a low activation energy of circa 0.35 eV being comparable with that of, e.g., LLZO-type garnets, which represent the current benchmark in this field. We propose these novel materials as a building block for a lattice-matching all-spinel solid-state battery with low interfacial resistance.
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Epp V, Gün Ö, Deiseroth HJ, Wilkening M. Long-range Li+ dynamics in the lithium argyrodite Li7PSe6 as probed by rotating-frame spin–lattice relaxation NMR. Phys Chem Chem Phys 2013; 15:7123-32. [DOI: 10.1039/c3cp44379e] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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45
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Kohl J, Nakhal S, Ferro N, Bottke P, Wilkening M, Bredow T, Heitjans P, Lerch M. Low-Temperature Synthesis, Characterization, and Stability of Spinel-Type Li2NiF4and Solid-Solutions Li2Ni1-xCoxF4. Z Anorg Allg Chem 2012. [DOI: 10.1002/zaac.201200455] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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46
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Islam MM, Wilkening M, Heitjans P, Bredow T. Insights into Li(+) Migration Pathways in α-Li3VF6: A First-Principles Investigation. J Phys Chem Lett 2012; 3:3120-3124. [PMID: 26296016 DOI: 10.1021/jz3014198] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Magnetic, structural, and defect properties of lithium vanadium hexafluoride (α-Li3VF6) are investigated theoretically with periodic quantum chemical methods. It is found that the ferromagnetic phase is more stable than the antiferromagnetic phase. The crystal structure contains three inequivalent Li sites (Li(1), Li(2), and Li(3)), where Li(1) occupies the middle position of the triplet Li(2)-Li(1)-Li(3). The calculated Li vacancy formation energies show that vacancy formation is preferred for the Li(1) and Li(3) sites compared to the Li(2) position. The Li exchange processes between Li(1) ↔ Li(3), Li(1) ↔ Li(2), and Li(2) ↔ Li(3) are studied by calculating the Li(+) migration between these sites using the climbing-image nudged elastic band approach. It is observed that Li exchange in α-Li3VF6 may take place in the following order: Li(1) ↔ Li(3) > (Li(1) ↔ Li(2) > Li(2) ↔ Li(3). This is in agreement with recently published results obtained from 1D and 2D (6)Li exchange nuclear magnetic resonance spectroscopy.
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Epp V, Nakhal S, Lerch M, Wilkening M. 2D Li Diffusion in Layer-Structured LixNbS2 as Probed by Frequency-Dependent T1 NMR Measurements. Z Anorg Allg Chem 2012. [DOI: 10.1002/zaac.201204082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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48
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Düvel A, Heitjans P, Wilkening M. Synthesis, Microstructure, and Transport Properties of Non-Equilibrium Fluorine Ion Conductors. Z Anorg Allg Chem 2012. [DOI: 10.1002/zaac.201204139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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49
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Bottke P, Ren Y, Bruce PG, Wilkening M. Ex situ NMR Measurements of Li Dynamics in TiO2 Anodes with an Ordered Hierarchical Pore Structure. Z Anorg Allg Chem 2012. [DOI: 10.1002/zaac.201204081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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50
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Ruprecht B, Wilkening M, Uecker R, Heitjans P. Extremely slow Li ion dynamics in monoclinic Li2TiO3--probing macroscopic jump diffusion via 7Li NMR stimulated echoes. Phys Chem Chem Phys 2012; 14:11974-80. [PMID: 22836957 DOI: 10.1039/c2cp41662j] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A thorough understanding of ion dynamics in solids, which is a vital topic in modern materials and energy research, requires the investigation of diffusion properties on a preferably large dynamic range by complementary techniques. Here, a polycrystalline sample of Li(2)TiO(3) was used as a model substance to study Li motion by both (7)Li spin-alignment echo (SAE) nuclear magnetic resonance (NMR) and ac-conductivity measurements. Although the two methods do probe Li dynamics in quite different ways, good agreement was found so that the Li diffusion parameters, such as jump rates and the activation energy, could be precisely determined over a dynamic range of approximately eleven decades. For example, Li solid-state diffusion coefficients D(σ) deduced from impedance spectroscopy range from 10(-23) m(2) s(-1) to 10(-12) m(2) s(-1) (240-835 K). These values are in perfect agreement with the coefficients D(SAE) deduced from SAE NMR spectroscopy. As an example, D(SAE) = 2 × 10(-17) m(2) s(-1) at 433 K and the corresponding activation energy determined by NMR amounts to 0.77(2) eV (400-600 K). At room temperature D(σ) takes a value of 3 × 10(-21) m(2) s(-1).
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