Proton insertion in spinel lithium manganates and the effect of manganese substitution

Aitchison, Phillip; Ammundsen, Brett; Bell, Anthony M. T.; Jones, Deborah J.; Rozière, Jacqués; Burns, Gary R.; Berg, H. van den; Tellgren, R.; Thomas, John O.

doi:10.1016/s0921-4526(99)01625-7

Cited by 9 publications

(8 citation statements)

References 3 publications

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“…21 In this case, the insertion of protons results in a vibration at 938 cm -1 , due to a lattice coupling of the H + -form spinel. 21,33,34 In the case of H + insertion in the perovskite structure, this lattice coupling mode of the proton could explain the vibration at 922 cm -1 , observed in AGED LLTO and samples exchanged in water (Li 0.30-y H y ) La 0.57 TiO 3 .…”

Section: Resultsmentioning

confidence: 95%

Reaction mechanisms of Li0.30La0.57TiO3 powder with ambient air: H+/Li+ exchange with water and Li2CO3 formation

et al. 2010

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The proton/lithium exchange property of the lithium lanthanum titanate Li(0.30)La(0.57)TiO(3) (named LLTO) is shown to occur at room temperature under ambient air. The (1)H and (7)Li MAS NMR, TGA analysis and IR spectroscopy techniques are used to probe reaction mechanisms. XRPD analysis gives evidence of the topotactic character of this exchange reaction. As for exchange in aqueous solution, it is shown that Li(0.30)La(0.57)TiO(3) is able to dissociate water on the grain surface and then to exchange H(+) for Li(+) into the perovskite structure. Lithium hydroxide is then formed on the grain surface and afterwards reacts with CO(2) contained in air to form Li(2)CO(3). It is shown that this mechanism is reversible. When the aged sample (aging in air for 5 months at room temperature) is annealed at 400 degrees C for two hours, the initial LLTO sample is totally recovered, a mass loss is observed and the carbonate signal in IR spectra disappears, demonstrating the reversibility of the carbonation reaction process.

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Section: Resultsmentioning

confidence: 95%

Reaction mechanisms of Li0.30La0.57TiO3 powder with ambient air: H+/Li+ exchange with water and Li2CO3 formation

et al. 2010

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“…The significant amount of hydrogen detected, especially in the spinel-start and spinel-100 materials, suggests that it can be located only at the surface of the particles, but also inside the spinel structure. According to litterature, in such spinel structures, the hydrogen atoms are likely to be located in 8a, 48f, or 96g sites. , A proton NMR study is planned in order to try to localize them in the structure. The progressive decrease in the hydrogen amount during the successive three annealings is in agreement with the continuous release of H 2 O, shown by mass spectroscopy.…”

Section: Resultsmentioning

confidence: 99%

“…According to litterature, in such spinel structures, the hydrogen atoms are likely to be located in 8a, 48f, 25 or 96g sites. 26,27 A proton NMR study is planned in order to try to localize them in the structure. The progressive decrease in the hydrogen amount during the successive three annealings is in agreement with the continuous release of H 2 O, shown by mass spectroscopy.…”

Section: X-ray and Neutronmentioning

confidence: 99%

Effect of Thermal Treatment on the Electronic Conductivity Properties of Cobalt Spinel Phases Synthesized by Electro-Oxidation in Ternary Alkaline Electrolyte (KOH, LiOH, NaOH)

et al. 2008

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A thermal treatment of Co3O4 type spinel phases, synthesized by electrooxidation of CoO powder in a mixed alkaline electrolyte (KOH, LiOH, NaOH), is shown to have an important influence on the electronic conductivity properties of the materials. The initial spinel phase contains hydrogen, lithium, cobalt vacancies, and especially Co4+ ions within the structure, leading to an electronic conductivity significantly larger than that of stoichiometric Co3O4. The thermal treatment, followed by in situ X-ray diffraction, TGA-MS and electronic conductivity measurements, induces a water release, coupled with an increase of the Co/O atomic ratio and a structural reorganization. The resulting cationic redistribution within the spinel framework entails an increase of the Co4+ amount in the [Co2O4] network and therefore of the electronic conductivity (by 3 orders of magnitude).

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“…1 H NMR thus evidence two types of proton: one in adsorbed water (not bonded to Co) and another one inside the spinel structure (involving a Co−O−H bonding), which could be located in tetrahedral sites, as reported for manganese spinel oxides. 36 To confirm these results and investigate more deeply the nature of the proton in the spinel structure, IR measurements have been performed on SP-initial. Figure 10 displays the high-frequency IR spectra of β(II)-Co(OH) 2 , HT-Co 3 O 4 , and SP-initial.…”

Section: ■ Introductionmentioning

confidence: 88%

“…These authors show also that in the case where a Mn vacancy is present in the vicinity of the proton, this latter is displaced, for energetic stability considerations, toward an edge of the tetrahedra (96g site) while still being covalently bonded to an oxygen atom. 15,36 The two tetrahedral environments evidenced by the team of Ammundsen can be considered for proton in our nanospinel cobalt oxides. They are in good accordance with the 1 H NMR signal which shows an H−O−Co covalent bond and with the infrared spectrum which suggests that hydrogen is involved in hydrogen bonding with other oxygen atoms of the tetrahedron.…”

Section: ■ Conclusionmentioning

confidence: 99%

Promising Nanometric Spinel Cobalt Oxides for Electrochemical Energy Storage: Investigation of Li and H Environments by NMR

et al. 2012

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Spinel-type cobalt oxides with formula H x Li y Co 3−δ O 4 exhibit interesting properties for various electrochemical energy storage applications thanks to their attractive electronic properties, due to the presence of H and Li ions in their structure as well as their nanometric dimensions. The effect of temperature on the H and Li environments is studied by investigating materials heat-treated at temperatures ranging from 25 to 650 °C by means of NMR spectroscopy. Two types of proton are evidenced: one bonded to oxygen atoms belonging to the network (hydroxyl group) and the other one involved in the H 2 O molecule. This configuration is in agreement with IR spectroscopy measurements, revealing the absence of free −OH groups, which mean that protons in the structure are involved in hydrogen bonds. After heat treatments at increasing temperature, NMR confirms that hydrogen is released, which induces first the migration of Li ions beyond 200 °C (probably from the 8a to the 16c sites), followed by a progressive reorganization of the structure with formation of HT-LiCoO 2 beyond 400 °C.

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Proton insertion in spinel lithium manganates and the effect of manganese substitution

Cited by 9 publications

References 3 publications

Reaction mechanisms of Li0.30La0.57TiO3 powder with ambient air: H+/Li+ exchange with water and Li2CO3 formation

Reaction mechanisms of Li0.30La0.57TiO3 powder with ambient air: H+/Li+ exchange with water and Li2CO3 formation

Effect of Thermal Treatment on the Electronic Conductivity Properties of Cobalt Spinel Phases Synthesized by Electro-Oxidation in Ternary Alkaline Electrolyte (KOH, LiOH, NaOH)

Promising Nanometric Spinel Cobalt Oxides for Electrochemical Energy Storage: Investigation of Li and H Environments by NMR

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