Jahn–Teller distortion and electronic structure of LiMn2O4

The effect of doping spinel LiMn 2 O 4 with chromium and magnesium has been studied using the first-principles spin density functional theory within GGA (generalized gradient approximation) and GGA+U. We find that GGA and GGA+U give different ground states for pristine LiMn 2 O 4 and same ground state for doped systems. For LiMn 2 O 4 the body centered tetragonal phase was found to be the ground state structure using GGA and face centered orthorhombic using GGA+U, while for LiM 0.5 Mn 1.5 O 4 (M= Cr or Mg) it was base centered monoclinic and for LiMMnO 4 (M= Cr or Mg) it was body centered orthorhombic in both GGA and GGA+U. We find that GGA predicts the pristine LiMn 2 O 4 to be metallic while GGA+U predicts it to be the insulating which is in accordance with the experimental observations. For doped spinels, GGA predicts the ground state to be half metallic while GGA+U predicts it to be insulating or metallic depending on the doping concentration. GGA+U predicts insulator-metal-insulator transition as a function of doping in case of Cr and in case of Mg the ground state is found to go from insulating to a half metallic state as a function of doping. Analysis of the charge density and the density of 2 states suggest a charge transfer from the dopants to the neighboring oxygen atoms and manganese atoms. We have calculated the Jahn-Teller active mode displacement Q 3 for doped compounds using GGA and GGA+U. The bond lengths calculated from GGA+U are found to be in better agreement with the experimental bond lengths. Based on the bond lengths of metal and oxygen, we have also estimated the average oxidation states of the dopants.

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“…42 for the orthorhombic phase. Our results are in agreement with the earlier studies done by Grechnev et al [44] and Ouyang et al [38].…”

Section: A Pristine Limn 2 Osupporting

confidence: 94%

“…The Goodenough -Kanamori rules [37] suggest that the interaction should be anti-ferromagnetic (AFM). Ouyang et al [38] have shown that GGA+U is necessary to obtain the AFM ground state. We have, therefore, performed spin polarized calculations for the AFM ordering of the manganese atoms.…”

Section: Computational Detailsmentioning

confidence: 99%

Suppression of Jahn–Teller distortion by chromium and magnesium doping in spinel LiMn2O4: A first-principles study using GGA and GGA+U

Singh

Gupta

Prasad

et al. 2009

Journal of Physics and Chemistry of Solids

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“…Note that the Mn 3+ is Jahn-Teller active; thus, the six Mn-O bonds in the Mn centered octahedron have two long bonds and four short bonds. 62,63 However, calculations with the PBE GGA in the present study predict the lowest energy for the cubic structure with all of the Mn ions having a 3.5…”

Section: Methodscontrasting

confidence: 49%

Lithium Concentration Dependent Elastic Properties of Battery Electrode Materials from First Principles Calculations

Hector

James

et al. 2014

J. Electrochem. Soc.

250

146

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This paper aims to help fill a gap in the literature on Li-ion battery electrode materials due to the absence of measured elastic constants needed for diffusion induced stress models. By examining results from new first principles density functional theory (DFT) calculations of LiCoO 2 , LiMn 2 O 4 , (and their delithiated hosts, CoO 2 and MnO 2 ), Li x Al alloys, and data from the extant literature on LiFePO 4 (and FePO 4 ), LiTi 2 O 4 (and Li 2 Ti 2 O 4 ), Li x Si, Li x Sn and lihtium graphite-interaction-compounds, a compelling picture emerges on the dependency of the elastic properties on Li concentration. Specifically, three distinct categories of behavior are found: (a) the averaged Young's moduli change very minimally upon lithiation of the spinel and olivine structures; (b) lithiation induced stiffening is observed only when new and stronger bonds between the Li ions and the host materials are formed in layered compounds; and (c) for alloy-forming electrode materials, such as Si, β-Sn and Al, the averaged Young's moduli of lithiated compounds follow the linear rule of mixtures. The tendency of ductile or brittle behavior electrode materials is investigated with the Pugh criterion, and a ductile to brittle transition was found to occur during lithiation of Al and β-Sn, but not in Si. One of the critical challenges in advanced lithium-ion (Li-ion) batteries is preventing fracture and mechanical failure of electrodes during lithium insertion and de-insertion. Most Li-ion battery electrodes experience volume changes associated with Li concentration changes within the host particles during charging and discharging.1 Graphite, for example, is the most common negative electrode for Li-ion batteries. Its volume increases by as much as 10% when Li intercalates between the sheets of C atoms.2 Compared to graphite, Si can store ∼10 times more Li, but it undergoes a massive volume expansion of the order of 300%.3 The large volume expansion, phase transition, and the associated Li diffusion-induced stresses (DIS) within electrode materials can lead to their fracture and failure which results in battery capacity loss and power fade.Significant progress toward understanding how DIS can be minimized to increase mechanical durability of Li-ion batteries 4-13 has been made. For example, Verbrugge and Cheng 11 modeled the evolution of stress and strain energy within a spherically-shaped electrode particle under either galvanostatic or potentiostatic operation. They also investigated the effects of surface energy and surface elasticity on the stress evolution in spherical electrodes.10 Wolfenstine 14 demonstrated that using Young's modulus, fracture toughness, and volume change, a critical particle size needed to lower capacity fade could be estimated with an analytical model. Recent models have been more material specific. Woodford et al. 15 further derived a failure criterion for crack propagation in individual Li x Mn 2 O 4 electrode particles during galvanostatic charging based on fracture mechanics. Using a combination...

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“…It shows that both lattice parameters and cell volumes decrease with increase in Cr to Mn mole fraction. It may be due to the partial substitution of Mn We expect the Jahn-Teller distortion is minimum during cycling with this modification [16]. The reason may be suggested as (1) ionic radius of Mn 3+ (0.645 Å) is larger than that of Mn 4+ ions (0.53 Å) and (2) the Cr/Mn-O interatomic distance increases with increase in Cr content (see Fig.…”

Section: Synthesis Of Licr X Mn 2-x O 4 Is As Followsmentioning

confidence: 83%

Structural characterization of LiCrxMn2−xO4 via a simple reflux technique

Purwaningsih¹,

Roto²,

Sutrisno³

et al. 2017

AIP Conference Proceedings

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Abstract. LiCr x Mn 2-x O 4 (x=0; 0.02; 0.04; 0.06; 0.08, 0.10) have been successfully synthesized via a facile and simple reflux technique. The SEM-EDS data confirm the presence of Cr, Mn and O elements in the products, while the XRD pattern suggests that the materials have well-developed cubic crystals. Direct method was applied to extract structural parameters of LiCr x Mn 2-x O 4 using the Fullprof and Oscail software in WinPlotr package program. Materials were refined in the crystal system, and space group of structures Fd3m phase were then identified. The lattice parameters decrease with the decrease in Cr content. The highest Li-O bond length was found for LiCr 0.10 Mn 1.90 O 4 . It was observed that there is no significant change in particle size as Cr content increased.

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Jahn–Teller distortion and electronic structure of LiMn2O4

Cited by 190 publications

References 31 publications

Suppression of Jahn–Teller distortion by chromium and magnesium doping in spinel LiMn2O4: A first-principles study using GGA and GGA+U

Suppression of Jahn–Teller distortion by chromium and magnesium doping in spinel LiMn2O4: A first-principles study using GGA and GGA+U

Lithium Concentration Dependent Elastic Properties of Battery Electrode Materials from First Principles Calculations

Structural characterization of LiCrxMn2−xO4 via a simple reflux technique

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