Structure and electrochemistry of lithium cobalt oxide synthesised at 400°C

Gummow, R. J.; Thackeray, Michael M.; David, William I. F.; Hull, S.

doi:10.1016/0025-5408(92)90062-5

Cited by 334 publications

(242 citation statements)

References 12 publications

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“…However, larger changes are observed with respect to the c-axis, in agreement with other works. 9,[59][60][61][62] The Rietveld refinement also confirmed the presence of a minority second phase of the spinel Co 3 O 4 in the blank test, gelatin and starch samples. This observation is related to the crystallite energy formation.…”

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confidence: 57%

“…A small amount of spinel Co 3 O 4 was found as secondary phase in the diffraction patterns of the blank test and of the starch and gelatin precursors, although HT-LiCoO 2 can be described as a major constituent. 6,9,[57][58][59][60][61][62] The XRD analyses of the HT-LiCoO 2 compounds synthesized with the precursors and the blank test were compared to evaluate the influence of the gelling agent in the product structural formation. The analysis of Figure 4 shows that the precursors' XRD has narrower peaks than the blank test.…”

Section: Resultsmentioning

confidence: 99%

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Synthesis and Characterization of LiCoO2 from Different Precursors by Sol‑Gel Method

Freitas

Siqueira

Costa

et al. 2017

J. Braz. Chem. Soc.

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Lithium cobalt oxide, LiCoO 2 , widely used as cathode in lithium ion batteries was synthesized and their structural and electronic properties investigated. The crystalline powders were prepared by the sol-gel method with four complexing agents: citric acid, glycine, starch and gelatin. These syntheses were compared with the blank test (without complexing agent). The X-ray diffraction and vibrational spectroscopy allowed the identification of the rhombohedral phase LiCoO 2 ( ) as the only or principal crystalline component in all samples. A small fraction of a second phase of cubic spinel Co 3 O 4 was observed in the samples of starch, gelatin and the blank test. The Rietveld refinements showed small structural variations, indicating reduced influence of the complexing agents on the synthesis. The theoretical HOMO-LUMO (highest occupied molecular orbital-lowest unoccupied molecular orbital) gap values are in agreement to those estimated by diffuse reflectance spectroscopy (DRS). The scanning electron microscopy (SEM) showed morphological pattern regardless of the complexing agent used, showing an alternative method.Keywords: LiCoO 2 , sol-gel method, XRD, Rietveld refinement, lithium ion batteries, DFT IntroductionLithium cobalt oxide, LiCoO 2 , has been the focus of many studies regarding their structural and electronic properties. [1][2][3][4][5][6][7][8] This system has interesting electrochemical features that allows a wide use as cathodes of lithium ion batteries. 2,4 The investigation of the structural aspects of the material is a crucial issue to better understand the electrochemical properties of the LiCoO 2 compound. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] For example, the nature of the crystal, its size and shape, are directly related with its electrochemical characteristics. 2 The LiCoO 2 synthesized at low temperatures (LT), below 500 °C, presents a cubic spinel structure ( ), while the synthesis at high temperatures (HT) (above 500 °C), generates the rhombohedral structure with stratified layers ( ). Therefore, several authors usually classify these structures as LT-LiCoO 2 and HT-LiCoO 2 , respectively . 1,2,7,8,[18][19][20][21][22][23][24] The rhombohedral phase is characterized by a structure with alternating layers of cobalt and lithium cations intercalated with oxygen anions. 22 The lithium and cobalt(III) ions are arranged in intercalated layers (Figure 1a). The cobalt(III) ion is located at the octahedral sites, forming a strong bond with the neighboring oxygen anion to constitute the Co−O layers (Figure 1b). Finally, the lithium layers are intercalated between the CoO 2 plans. 1,3,4 The octahedral sites of these layers are occupied by lithium and cobalt(III) ions alternately that forms a sequential stacking with oxygen ion layers in a close packing of the ABCABC type ( Figure 1c). 4,5 This specific stacking arrangement leads to an environment equivalent for all ions, allowing the maximum charge delocalization and the minimal system energy. 1,3,4 The degree of crystal orde...

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confidence: 57%

Section: Resultsmentioning

confidence: 99%

Synthesis and Characterization of LiCoO2 from Different Precursors by Sol‑Gel Method

Freitas

Siqueira

Costa

et al. 2017

J. Braz. Chem. Soc.

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“…Previous in-situ studies of LiCoO2 using commercial batteries by Sharma et al [45] showed that both forms of LiCoO2; the hexagonal one and the spinel-like phase [46][47][48][49][50][51][52], undergo a series of phase transitions during cycling, and it was proposed that the gradual build-up of the spinel-type phase might be a contributing factor to the observed capacity fade within LixCoO2 based batteries. Rodriguez et al [53] determined the variations in the lattice parameters of a LiCoO2-type material as a function of charge state, also in a commercial Liion cell, whilst changes in both the lattice parameters and lithium occupancies with repeated cell cycling were shown to be correlated with the degradation of cell performance [54].…”

Section: In-situ Structural Changes Of Licoo2mentioning

confidence: 99%

In-Situ Neutron Studies of Electrodes for Li-Ion Batteries Using a Deuterated Electrolyte: LiCoO₂as a Case Study

Dong

Biendicho

Hull

et al. 2018

J. Electrochem. Soc.

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Abstract.An electrochemical cell for in-situ neutron powder diffraction studies of electrode materials for lithium-ion batteries is presented. The device has a coin cell geometry, consisting of 8.4 cm diameter, circular components that can be stacked together and clamped tight using sixteen polyetheretherketone (PEEK) screws. The background issue associated with incoherent scattering from hydrogen within the organic electrolyte was addressed by replacing the normal electrolyte with a deuterated analogue, significantly improving the peak-to-background ratio of the in-situ neutron data. Initial in-situ studies showed clear structural evolution within LixCoO2 during charge in a half-cell with lithium metal as the counter electrode, in agreement with previous studies. In addition, the in-situ cell was shown to provide electrochemical performance comparable to that of equivalent coin cells of the commercial design and, following these demonstration studies, is available for in-situ structural studies of other lithium cathode and anode materials during charge/discharge cycling. 2 1. Introduction.

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“…HT-LiCoO 2 has a layered-type (rhombohedral) structure with symmetry R3m. The lithium and metal ions occupy alternate layers in octahedral sites between the cubic close-packed oxygen planes [4]. On the other hand, the LT-LiCoO 2 is related to a spinel-type structure (cubic structure) with symmetry Fd3m.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, the LT-LiCoO 2 is related to a spinel-type structure (cubic structure) with symmetry Fd3m. Gummow et al [4,5], using neutron diffraction, showed that LTLiCoO 2 has a similar structure to HT-LiCoO 2 with 6% of the cobalt ions in the lithium layer.…”

Section: Introductionmentioning

confidence: 99%

Structural and electrochemical properties of LiCoO2 prepared by combustion synthesis

Santiago

2003

Solid State Ionics

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LiCoO 2 powders were prepared by combustion synthesis, using metallic nitrates as the oxidant and metal sources and urea as fuel. A small amount of the LiCoO 2 phase was obtained directly from the combustion reaction, however, a heat treatment was necessary for the phase crystallization. The heat treatment was performed at the temperature range from 400 up to 700 jC for 12 h. The powders were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and specific surface area values were obtained by BET isotherms. Composite electrodes were prepared using a mixture of LiCoO 2 , carbon black and poly(vinylidene fluoride) (PVDF) in the 85:10:5% w/w ratio. The electrochemical behavior of these composites was evaluated in ethylene carbonate/dimethylcarbonate solution, using lithium perchlorate as supporting electrolyte. Cyclic voltammograms showed one reversible redox process at 4.0/3.85 V and one irreversible redox process at 3.3 V for the LiCoO 2 obtained after a post-heat treatment at 400 and 500 jC.Raman spectroscopy showed the possible presence of LiCoO 2 with cubic structure for the material obtained at 400 and 500 jC. This result is in agreement with X-ray data with structural refinement for the LiCoO 2 powders obtained at different temperatures using the Rietveld method. Data from this method showed the coexistence of cubic LiCoO 2 (spinel) and rhombohedral (layered) structures when LiCoO 2 was obtained at lower temperatures (400 and 500 jC). The single rhombohedral structure for LiCoO 2 was obtained after post-heat treatment at 600 jC. The maximum energy capacity in the first discharge was 136 mA g À 1 for the composite electrode based on LiCoO 2 obtained after heat treatment at 700 jC. D

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Structure and electrochemistry of lithium cobalt oxide synthesised at 400°C

Cited by 334 publications

References 12 publications

Synthesis and Characterization of LiCoO2 from Different Precursors by Sol‑Gel Method

Synthesis and Characterization of LiCoO2 from Different Precursors by Sol‑Gel Method

In-Situ Neutron Studies of Electrodes for Li-Ion Batteries Using a Deuterated Electrolyte: LiCoO₂as a Case Study

Structural and electrochemical properties of LiCoO2 prepared by combustion synthesis

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Structure and electrochemistry of lithium cobalt oxide synthesised at 400°C

Cited by 334 publications

References 12 publications

Synthesis and Characterization of LiCoO2 from Different Precursors by Sol‑Gel Method

Synthesis and Characterization of LiCoO2 from Different Precursors by Sol‑Gel Method

In-Situ Neutron Studies of Electrodes for Li-Ion Batteries Using a Deuterated Electrolyte: LiCoO2as a Case Study

Structural and electrochemical properties of LiCoO2 prepared by combustion synthesis

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In-Situ Neutron Studies of Electrodes for Li-Ion Batteries Using a Deuterated Electrolyte: LiCoO₂as a Case Study