Journal ArticleDOI
Lattice Dynamics and Vibrational Spectra of Lithium Manganese Oxides: A Computer Simulation and Spectroscopic Study
TLDR
In this paper, the lattice vibrational modes of spinel-structured lithium manganese oxides have been calculated using atomistic modeling methods, and the results support a model for the Li 0.5Mn2O4 lattice in which the lithium ions are ordered.Abstract:
The lattice vibrational modes of spinel-structured lithium manganese oxides have been calculated using atomistic modeling methods. The simulations allow the Raman and infrared spectra of lithiated, fully delithiated, and partially delithiated phases to be assigned for the first time. Calculations for the spinels LiMn2O4, λ-MnO2, and Li0.5Mn2O4 are compared with experimental Raman data measured for thin films of the oxides coated on a platinum electrode. The appearance of a number of new bands in the Raman spectrum of LiMn2O4 following partial extraction of lithium is shown to result from local lowering of the symmetry and Raman activation of modes which are optically inactive or only infrared active in LiMn2O4. The results support a model for the Li0.5Mn2O4 lattice in which the lithium ions are ordered. The deformation vibrations of lattice hydroxyl “defects” in λ-MnO2 have also been calculated; comparison of the calculated and experimental vibrational data supports a model in which hydroxyl species are l...read more
Citations
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Journal ArticleDOI
The general utility lattice program (GULP)
Julian D. Gale,Andrew L. Rohl +1 more
TL;DR: The General Utility Lattice Program (GULP) as discussed by the authors has been extended to include the ability to simulate polymers and surfaces, as well as adding many other new features, and the current status of the program is fully documented.
Journal ArticleDOI
Atomic-scale investigation of defects, dopants, and lithium transport in the LiFePO4 olivine-type battery material
TL;DR: In this paper, the authors investigated the intrinsic defects, dopant incorporation, and lithium ion migration in the LiFePO4 electrode material using well-established atomistic modeling techniques.
Journal ArticleDOI
Lattice vibrations of manganese oxides. Part I. Periodic structures.
TL;DR: Structural trends are deduced from the comparison of the vibrational spectra of the MDO phases investigated: birnessite, bixbyite, coronadite, groutite, hausmannite, hollandite, manganosite, pyrolusite, ramsdellite, romanechite, spinel, and todorokite.
Journal ArticleDOI
Raman Microspectrometry Applied to the Study of Electrode Materials for Lithium Batteries
TL;DR: This work concludes that vanadium Pentoxide V2O5 Structure and Phospho-olivine LiFePO4 Compound 1312 are likely to have similar compositions to that of Manganese Oxide-Based Compounds 1291.
Journal ArticleDOI
Lithium Battery Materials LiMPO4 (M = Mn, Fe, Co, and Ni): Insights into Defect Association, Transport Mechanisms, and Doping Behavior
TL;DR: In this article, the defect chemistry, doping behavior, and ion migration in olivine-type materials LiMPO4 (M = Mn, Fe, Co, and N) are investigated by atomistic simulation techniques.
References
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Journal ArticleDOI
GULP: A computer program for the symmetry-adapted simulation of solids
TL;DR: Accelerated convergence techniques for the dispersion energy are found to be beneficial in improving the precision at little extra computational cost, particularly when a one centre decomposition is possible or the Ewald sum weighting towards real-space is increased.
Journal ArticleDOI
Theory of the Dielectric Constants of Alkali Halide Crystals
B. G. Dick,A. W. Overhauser +1 more
TL;DR: In this article, a short-range repulsive interaction between ions with closed shell electron configurations is investigated, and an approximate interpretation of the Born-Mayer potential in terms of overlap integrals is developed.
Journal ArticleDOI
Conduction in polar crystals. I. Electrolytic conduction in solid salts
N. F. Mott,M. J. Littleton +1 more
TL;DR: Etude theorique de la conductivite des solides (NaCl, KCl, RbCl, LiF, NaF, NN, NaBr, NaI, KI, I, KB, KK, KBr, RBCl, NBr, NB, NCl, NaB, NaC, NC, NaD, NaE, NE, NaG, NG, NaX, NX, NaV, NaZ, NaY, NaO, NaW, NaN, N
Journal ArticleDOI
Capacity Fading on Cycling of 4 V Li / LiMn2 O 4 Cells
Abstract: The cycle-life behavior of a Li/1 M-LiPF 6 + EC/DMC(1:2 by volume)/LiMn 2 O 4 cell was investigated at various temperatures (0, 25, and 50°C). The capacity fades faster on cycling at high rather than low temperatures. The mechanisms responsible for the capacity fading of the spinel LiMn 2 O 4 during cycling were extensively investigated by chemical analysis of the dissolved Mn in combination with in situ x-ray diffraction, Rietveld analysis, and ac impedance techniques. Chemical analytical results indicated that the capacity loss caused by the simple dissolution of Mn 3+ accounted for only 23 and 34% of the overall capacity losses cycling at room temperature and 50°C, respectively. In situ x-ray diffraction results showed that the two-phase structure coexisting in the high-voltage region persists during lithium-ion insertion/extraction at low temperatures during cycling. By contrast, this two-phase structure was effectively transformed to a more stable, one-phase structure, accompanied by the dissolution of Mn and the loss of oxygen (e.g., Mn 2 O 3 .MnO) at the high temperature; this dominated the overall capacity-loss process. AC impedance spectra revealed that the capacity loss at the high temperature was also due in part to the decomposition of electrolyte solution at the electrode.
Journal ArticleDOI
Interpretation of the vibrational spectra of spinels
William B. White,B.A. DeAngelis +1 more
TL;DR: In this article, the vibrational spectrum of the spinel structure is treated by a factor group analysis and four IR active and five Raman active bands are predicted in agreement with observation.