Effect of pressure on the structural properties and Raman modes of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mi>LiCoO</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>

Wang, X.; Loa, I.; Kunc, K.; Syassen, K.; Amboage, M.

doi:10.1103/physrevb.72.224102

Cited by 52 publications

(34 citation statements)

References 41 publications

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“…By contrast, the 489 cm −1 mode shows E g symmetry. The E g mode involves in-plane O-Co-O bending motions, whereas the A 1g mode results from out-of-plane Co-O stretching motions [15][16][17][18]. The low-intensity broad contributions of phonon modes around 1000 and 1175 cm −1 should be ascribed to multiphonon processes.…”

Section: Electronic Excitationsmentioning

confidence: 94%

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Electronic structure and lattice dynamics of Li_xCoO₂single crystals

et al. 2015

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Spectroscopic ellipsometry and Raman scattering measurements of single-crystal Li x CoO 2 (x = 0.33, 0.43, 0.50, 0.53, 0.72, and 0.87) are reported. The room temperature optical absorption spectra for x values in the range of 0.33-0.72 exhibit three bands near 1.60, 3.35, and 5.20 eV. On the basis of firstprinciples calculations, the observed optical excitations were appropriately assigned. The chargetransfer absorption bands shift to higher energies in Li 0.87 CoO 2 because of symmetry-breakinginduced distortions of the hybridized Co-O orbitals with shifted oxygen 2p states. Furthermore, two Raman-active phonon modes, which display E g and A 1g symmetry, are sensitive to lithium doping. Upon cooling across 200 K, which is the antiferromagnetic phase transition temperature of Li 0.50 CoO 2 , large splitting of the E g mode and a discontinuous change in the frequency of the A 1g mode were observed. These results highlight the importance of spin-phonon coupling in Li 0.50 CoO 2 .

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Section: Electronic Excitationsmentioning

confidence: 94%

“…Despite intense research having been conducted on layered lithium cobaltites, their optical and phonon properties have remained relatively unexplored [11,12,[15][16][17][18]. Moreover, previous studies on Li x CoO 2 were limited to powder samples.…”

Section: Introductionmentioning

confidence: 99%

Electronic structure and lattice dynamics of Li_xCoO₂single crystals

et al. 2015

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“…Wang et al, for instance, reported a decrease in the E g :A 1g ratio for upon the application of compressive strain. 19 Compressive strain, in turn, reduces the c-axis length. Delithiation induces the inverse, namely an expansion of the c-axis and by extension E g :A 1g ratio.…”

Section: Resultsmentioning

confidence: 99%

Measuring Li⁺Inventory Losses in LiCoO₂/Graphite Cells Using Raman Microscopy

Snyder

Apblett

Grillet

et al. 2016

J. Electrochem. Soc.

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The contribution from loss of Li + inventory to capacity fade is described for slow rates (C/10) and long-term cycling (up to 80 cycles). It was found through electrochemical testing and ex-situ Raman analysis that at these slow rates, the entirety of capacity loss up to 80 cycles can be explained by loss of Li + inventory in the cell. The Raman spectrum of LiCoO 2 is sensitive to the state of lithiation and can therefore be leveraged to quantify the state of lithiation for individual particles. With these Raman derived estimates, the lithiation state of the cathode in the discharged state is compared to electrochemical data as a function of cycle number. High correlation is found between Raman quantifications of cycleable lithium and the capacity fade. Additionally, the linear relationship between discharge capacity and cell overpotential suggests that the loss of capacity stems from an impedance rise of the electrodes, which based on Li inventory losses, is caused by SEI formation and repair. Lithium ion batteries (LIB) provide the highest energy densities compared to other rechargeable battery types.1 For this reason, they are being pursued for usage in advanced applications such as electric vehicles and storage of intermittent renewable energies (solar, wind, etc.). Despite their promise, degradation caused by both chemical and physical mechanisms diminishes LIB performance. Chemically, formation of a solid electrolyte interphase (SEI) on the surface of both the graphite anode and the LiCoO 2 cathode accompanied by other side reactions between the electrolyte and the electrode surface 2 results in the loss of cycleable Li + and thus capacity. These surface films also increase electrode impedance, which can shorten the time for the cell to reach cutoff voltages and affect rate capability of the cell. 3,4 Capacity loss can also originate due to physical mechanisms. For example, stress may accumulate in electrode materials during lithiation and delithiation owing to the large volumetric alterations induced by these processes. 4,5 Volumetric expansion can be up to 10% in graphite and ∼1.6% in LiCoO 2 .6,7 Such expansion and the induced stress can, in turn, lead to fracturing of active particles, cracking and reforming of the SEI, and loss of contact among electrode components (i.e., active material, polymeric binder, and current collectors). 4 Taken together, these chemical and physical degradation mechanisms induce capacity fade with repeated cycling that curtail the lifetime of the battery.Beyond identification, it is necessary to assess the relative influence of individual mechanisms to the totality of capacity fade. 3,8,9 Specifically, comparisons between the relative impact of several mechanisms-primary active material loss (Li + inventory), secondary active material loss (LiCoO 2 and/or graphite), and increased internal cell resistance (caused by surface films)-remain the topic of continued investigation.3 Such effort is complicated by the dependence of these mechanisms to several parameters as it has been...

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“…Theoretical calculations suggest $150 GPa for the Young's modulus of Li 1-x CoO 2 at x ¼ 0. [29] Internal microcracking is not avoidable with expansion anisotropies and elastic moduli of this order. Indeed, in situ acoustic emission experiments (to be discussed elsewhere) revealed extensive internal microcracking events occurring during the initial cycles, which however subsided rapidly thereafter.…”

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confidence: 98%

Ultrahigh‐Energy‐Density Microbatteries Enabled by New Electrode Architecture and Micropackaging Design

et al. 2010

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Monolithic cathodes of optimized porosity prepared by sintering LiCoO2 powders provide high volume utilization and surprising stability under electrochemical cycling. Combined with a novel packaging approach, ultrahigh energy densities in small volumes are enabled. The microbatteries have volumes <6 mm3 and provide sustained ∼2.5 h discharges with energy densities of 400–650 W h L−1.

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Effect of pressure on the structural properties and Raman modes ofLiCoO2

Cited by 52 publications

References 41 publications

Electronic structure and lattice dynamics of Li_xCoO₂single crystals

Electronic structure and lattice dynamics of Li_xCoO₂single crystals

Measuring Li⁺Inventory Losses in LiCoO₂/Graphite Cells Using Raman Microscopy

Ultrahigh‐Energy‐Density Microbatteries Enabled by New Electrode Architecture and Micropackaging Design

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Effect of pressure on the structural properties and Raman modes ofLiCoO2

Cited by 52 publications

References 41 publications

Electronic structure and lattice dynamics of LixCoO2single crystals

Electronic structure and lattice dynamics of LixCoO2single crystals

Measuring Li+Inventory Losses in LiCoO2/Graphite Cells Using Raman Microscopy

Ultrahigh‐Energy‐Density Microbatteries Enabled by New Electrode Architecture and Micropackaging Design

Contact Info

Product

Resources

About

Electronic structure and lattice dynamics of Li_xCoO₂single crystals

Electronic structure and lattice dynamics of Li_xCoO₂single crystals

Measuring Li⁺Inventory Losses in LiCoO₂/Graphite Cells Using Raman Microscopy