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Title: Identify OH groups in TiOF{sub 2} and their impact on the lithium intercalation properties

Abstract

A detailed investigation on the chemical composition of the cubic form of titanium oxyfluoride-based compound reveals the presence of OH groups substituting the oxide/ fluoride sublattice. The substitution of oxide by hydroxyl groups induces the presence of titanium vacancies (□) which were characterized by {sup 1}H and {sup 19}F solid-state NMR. {sup 1}H NMR shows that OH groups are present as bridging Ti-OH-Ti or terminal OH groups, i.e. sitting close to a titanium vacancy Ti-OH-□. The electrochemical properties vs. Li{sup +}/Li indicates that the presence of OH groups prevents the intercalation of lithium in the upper voltage region (1.2–3 V vs. Li{sup +}/Li). Indeed, a partial dehydroxylation of the framework enables to improve the reversibility of the lithium insertion/de-insertion processes. Since the presence of OH groups in this type of compounds is usual and depends on the synthesis method employed, this work enables to rationalize the different electrochemical behaviors reported in the literature and further highlights the importance of a good knowledge of the chemical composition with regard to the physico-chemical properties. - Graphical abstract: The substitution of oxide by hydroxyl groups inducing the formation of titanium vacancies (□), i.e., Ti{sub 1−x}□{sub x}O{sub 1-4x}(OH){sub 4x+y}F{sub 2−y}, was characterized by solid-statemore » {sup 1}H and {sup 19}F NMR. - Highlights: • Evidences of the presence of OH groups and titanium vacancies in titanium oxyfluoride. • {sup 1}H NMR showed the presence of Ti-OH-Ti and Ti-OH-□ species. • The presence of OH groups limits the insertion of lithium within the interstitial sites.« less

Authors:
 [1]; ;  [2];  [1]
  1. Sorbonne Universités, UPMC Univ Paris 06, CNRS UMR 8234 PHENIX, 75005 Paris (France)
  2. Université Bretagne Loire, Université du Maine, UMR CNRS 6283, Institut des Molécules et des Matériaux du Mans (IMMM), Avenue Olivier Messiaen, 72085 Le Mans Cedex 9 (France)
Publication Date:
OSTI Identifier:
22658173
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 246; Other Information: Copyright (c) 2016 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CHEMICAL COMPOSITION; CLATHRATES; ELECTRIC POTENTIAL; EXPERIMENTAL DATA; FLUORINE COMPOUNDS; HYDROXYL RADICALS; LITHIUM IONS; NUCLEAR MAGNETIC RESONANCE; OXIDATION; OXIDES; TITANIUM COMPOUNDS; VACANCIES

Citation Formats

Li, Wei, Body, Monique, Legein, Christophe, and Dambournet, Damien, E-mail: damien.dambournet@upmc.fr. Identify OH groups in TiOF{sub 2} and their impact on the lithium intercalation properties. United States: N. p., 2017. Web. doi:10.1016/J.JSSC.2016.11.010.
Li, Wei, Body, Monique, Legein, Christophe, & Dambournet, Damien, E-mail: damien.dambournet@upmc.fr. Identify OH groups in TiOF{sub 2} and their impact on the lithium intercalation properties. United States. doi:10.1016/J.JSSC.2016.11.010.
Li, Wei, Body, Monique, Legein, Christophe, and Dambournet, Damien, E-mail: damien.dambournet@upmc.fr. Wed . "Identify OH groups in TiOF{sub 2} and their impact on the lithium intercalation properties". United States. doi:10.1016/J.JSSC.2016.11.010.
@article{osti_22658173,
title = {Identify OH groups in TiOF{sub 2} and their impact on the lithium intercalation properties},
author = {Li, Wei and Body, Monique and Legein, Christophe and Dambournet, Damien, E-mail: damien.dambournet@upmc.fr},
abstractNote = {A detailed investigation on the chemical composition of the cubic form of titanium oxyfluoride-based compound reveals the presence of OH groups substituting the oxide/ fluoride sublattice. The substitution of oxide by hydroxyl groups induces the presence of titanium vacancies (□) which were characterized by {sup 1}H and {sup 19}F solid-state NMR. {sup 1}H NMR shows that OH groups are present as bridging Ti-OH-Ti or terminal OH groups, i.e. sitting close to a titanium vacancy Ti-OH-□. The electrochemical properties vs. Li{sup +}/Li indicates that the presence of OH groups prevents the intercalation of lithium in the upper voltage region (1.2–3 V vs. Li{sup +}/Li). Indeed, a partial dehydroxylation of the framework enables to improve the reversibility of the lithium insertion/de-insertion processes. Since the presence of OH groups in this type of compounds is usual and depends on the synthesis method employed, this work enables to rationalize the different electrochemical behaviors reported in the literature and further highlights the importance of a good knowledge of the chemical composition with regard to the physico-chemical properties. - Graphical abstract: The substitution of oxide by hydroxyl groups inducing the formation of titanium vacancies (□), i.e., Ti{sub 1−x}□{sub x}O{sub 1-4x}(OH){sub 4x+y}F{sub 2−y}, was characterized by solid-state {sup 1}H and {sup 19}F NMR. - Highlights: • Evidences of the presence of OH groups and titanium vacancies in titanium oxyfluoride. • {sup 1}H NMR showed the presence of Ti-OH-Ti and Ti-OH-□ species. • The presence of OH groups limits the insertion of lithium within the interstitial sites.},
doi = {10.1016/J.JSSC.2016.11.010},
journal = {Journal of Solid State Chemistry},
number = ,
volume = 246,
place = {United States},
year = {Wed Feb 15 00:00:00 EST 2017},
month = {Wed Feb 15 00:00:00 EST 2017}
}
  • A facile and general methodology for the development of metal–organic frameworks (MOFs) functionalized with pendant, aromatic hydroxyl (-OH) groups is presented. Extensive gas-sorption studies in representative and important MOFs functionalized with free aromatic -OH groups such as the IRMOF-8 and DUT-6 (or MOF-205), denoted here as 1 and 2, revealed a high CO 2/CH 4 selectivity for 1 (13.6 at 273 K and 1 bar) and a high NH 3 uptake of 16.4 mol kg –1 at 298 K and 1 bar for 2.
  • The new compounds Fe{sub 4}(OH){sub 3}(PO{sub 4}){sub 3} and V{sub 4}O(OH){sub 2}(PO{sub 4}){sub 3} are prepared hydrothermally by reaction of Fe{sub 2}O{sub 3} and V{sub 2}O{sub 3} with aqueous H{sub 3}PO{sub 4} solutions. X-ray powder diffraction shows that the two compounds have the same monoclinic structure. Fe{sub 4}(OH){sub 3}(PO{sub 4}){sub 3} crystallizes with unit cell parameters a = 19.555(2), b = 7.376(1), c = 7.429(1) {angstrom}, and {beta} = 102.26(1){degree} in the space group C2/c with Z = 4. Dimers of face-sharing (nonequivalent) FeO{sub 6} octahedra are interconnected by OH groups to form a double-chain of dimers extended along themore » c axis. Double chains are linked to one another by PO{sub 4} tetrahedra that share corners with the octahedra. The Moessbauer spectrum of Fe{sub 4}(OH){sub 3}(PO{sub 4}){sub 3} at 293 K exhibits two narrow width quadrupole doublets of equal intensity, with nearly identical isomer shifts and different quadrupole splittings: {delta}{sub 1} = 0.407 mm/sec, {delta}{sub 2} = 0.403 mm/sec, {Delta}E{sub 1} = 0.657 mm/sec, {Delta}E{sub 2} = 0.294 mm/sec. Low-temperature spectra indicate magnetic hyperfine splitting and three-dimensional magnetic order among the dimers at 86.7 {plus minus} 0.2 K. Below the ordering temperature, the spectrum consists of two equal intensity sextets with saturation hyperfine fields (4.2 K) of 52.9 and 49.1 T, respectively. The temperature dependence of the magnetic susceptibility confirms that ordering occurs at 87 {plus minus} 0.5 K with an abrupt rise to a high-moment ferromagnetic state. Above the ordering temperature, the susceptibility data exhibits a broad maximum at about 125 K characteristic of antiferromagnetically coupled dimers. The moment vs. temperature behavior of V{sub 4}O(OH){sub 2}(PO{sub 4}){sub 3} also shows antiferromagnetic exchange that is likely pairwise in nature.« less
  • This paper reports the syntheses and characterization of two phosphonate compounds Cd{l_brace}(2-C{sub 5}H{sub 4}NO)CH(OH)PO{sub 3}{r_brace}(H{sub 2}O){sub 2} (1) and Zn{l_brace}(4-C{sub 5}H{sub 4}NO)CH(OH)PO{sub 3}{r_brace} (2) based on hydroxy(2-pyridyl N-oxide)methylphosphonic and hydroxy(4-pyridyl N-oxide)methylphosphonic acids. Compound 1 has a chain structure in which dimers of edge-shared {l_brace}CdO{sub 6}{r_brace} octahedra are linked by {l_brace}CPO{sub 3}{r_brace} tetrahedra through corner-sharing. The pyridyl rings reside on the two sides of the inorganic chain. Compound 2 has a layer structure where the inorganic chains made up of corner-sharing {l_brace}ZnO{sub 4}{r_brace} and {l_brace}CPO{sub 3}{r_brace} tetrahedra are covalently connected by pyridyl N-oxide groups. Crystal data for 1: triclinic, space groupmore » P1-bar , a=6.834(1)A, b=7.539(1)A, c=10.595(2)A, {alpha}=84.628(3){sup o}, {beta}=74.975(4){sup o}, {gamma}=69.953(4){sup o}. For 2: triclinic, space group P1-bar , a=5.219(1)A, b=8.808(2)A, c=9.270(2)A, {alpha}=105.618(5){sup o}, {beta}=95.179(4){sup o}, {gamma}=94.699(4){sup o}.« less
  • The mechanical properties of Li{sub x}CoO{sub 2} under various Li concentrations and associated anisotropy have been systematically studied using the first principles method. During the lithium intercalation process, the Young's modulus, bulk modulus, shear modulus, and ultimate strength increase with increasing lithium concentration. Strong anisotropy of mechanical properties between a-axis and c-axis in Li{sub x}CoO{sub 2} is identified at low lithium concentrations, and the anisotropy decreases with increasing lithium concentration. The observed lithium concentration dependence and anisotropy are explained by analyzing the charge transfer using Bader charge analysis, bond order analysis, and bond strength by investigating partial density of statesmore » and charge density difference. With the decrease of Li concentration, the charge depletion in the bonding regions increases, indicating a weaker Co-O bond strength. Additionally, the Young's modulus, bulk modulus, shear modulus, and toughness are obtained by simulating ab initio tensile tests. From the simulated stress-strain curves, Li{sub x}CoO{sub 2} shows the highest toughness, which is in contraction with Pugh criterion prediction based on elastic properties only.« less