Development of In Situ Cross-Sectional Raman Imaging of LiCoO&lt;sub&gt;2&lt;/sub&gt; Cathode for Li-ion Battery

Fukumitsu, Hitoshi; Ōmori, Makoto; Terada, Kenji; Suehiro, Shogo

doi:10.5796/electrochemistry.83.993

Cited by 19 publications

(15 citation statements)

References 28 publications

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“…This technique also allowed the detection of a secondary product Co 3 O 4 , which has five active bands (A 1g , E g and 3F 2g ), with the most intense around the 690 cm -1 . [53][54][55][56] Below 650 cm -1 , the Raman spectra of the compounds show two bands around 597 and 488 cm -1 , which are assigned to the A 1g and E g vibrational modes of HT-LiCoO 2 phase, respectively. For the compound synthesized with gelatin it was found a band in 692 cm -1 that is characteristic of the spinel Co 3 O 4 .…”

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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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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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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“…Investigation of the peak positions of A 1g bands gives SOC mapping images for LiCoO 2 electrodes. 8,16,17 In the NMC electrodes, the peaks of E g and A 1g modes are quite broad because Raman spectrum of NMC contains of several bands attributable to Ni-O (474, 554 cm ¹1 ), Mn-O (594 cm ¹1 ) and Co-O (486, 596 cm ¹1 ). 14 To investigate SOC in the NMC electrodes, evaluation of peak positions of A 1g modes is difficult because of broad peaks for A 1g modes.…”

Section: Electrochemistrymentioning

confidence: 99%

Raman Spectroscopy for LiNi1/3Mn1/3Co1/3O2 Composite Positive Electrodes in All-Solid-State Lithium Batteries

et al. 2016

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Raman spectroscopy was conducted for LiNi 1/3 Mn 1/3 Co 1/3 O 2 (NMC) composite positive electrodes in all-solid-state batteries using Li 2 S-P 2 S 5 solid electrolytes. Raman spectral changes attributable to structural changes of NMC were observed during the initial charge-discharge test. To evaluate state-of-charge (SOC) distributions in the NMC electrodes, Raman mapping was carried out for the electrodes of charged and discharged cells. The mapping images indicated that most NMC particles were uniformly delithiated and lithiated by the charge-discharge process. It is noteworthy that uniform charge-discharge reactions proceeded in the NMC electrodes.

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“…With operando analysis, real functional microbatteries can be studied, without sample preparation artifacts, and obtaining results is much quicker than for ex situ experiments. Several studies report result on in situ Raman measurements on LiCoO 2 during electrochemical cycling in liquid configuration. Otoyama et al report results on LiCoO 2 powder in an all‐solid‐state battery with a dedicated design for in situ analysis.…”

Section: Introductionmentioning

confidence: 99%

Ex situ and operando study of LiCoO₂ thin films by Raman spectroscopy: Thermal and electrochemical properties

Van‐Jodin

Rouchon

et al. 2019

J Raman Spectroscopy

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Lithiated transition metal oxides are active materials used as positive electrode in lithium ion cells thanks to their high capacity and air stability when. Amongst lithiated oxides, LiCoO2 is the most commonly and practically used due to its high‐specific energy and its excellent cycle life. This work focuses on phase transformation of LiCoO2 thin films during the annealing step and during the cycling life. The formation of unwanted products is highlighted by an innovative method: in situ Raman analysis. During the annealing used to transform the almost amorphous as‐deposited LiCoO2 into the rhombohedral structure useful for electrochemical cycling, the formation of Co3O4 has been observed. The second studied phase transformation is due to the electrochemical cycling and highlights the kinetics of the structure change. The study was done by comparing ex situ and operando results and highlights the main advantages of operando analysis: more data in a shorter time and the ability to assess the time dependence of phenomena.

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Development of In Situ Cross-Sectional Raman Imaging of LiCoO<sub>2</sub> Cathode for Li-ion Battery

Cited by 19 publications

References 28 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

Raman Spectroscopy for LiNi<sub>1/3</sub>Mn<sub>1/3</sub>Co<sub>1/3</sub>O<sub>2</sub> Composite Positive Electrodes in All-Solid-State Lithium Batteries

Ex situ and operando study of LiCoO₂ thin films by Raman spectroscopy: Thermal and electrochemical properties

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Development of In Situ Cross-Sectional Raman Imaging of LiCoO<sub>2</sub> Cathode for Li-ion Battery

Cited by 19 publications

References 28 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

Raman Spectroscopy for LiNi<sub>1/3</sub>Mn<sub>1/3</sub>Co<sub>1/3</sub>O<sub>2</sub> Composite Positive Electrodes in All-Solid-State Lithium Batteries

Ex situ and operando study of LiCoO2 thin films by Raman spectroscopy: Thermal and electrochemical properties

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Ex situ and operando study of LiCoO₂ thin films by Raman spectroscopy: Thermal and electrochemical properties