Structural defects in LiCoO2 studied by L7i nuclear magnetic relaxation

Kim, J. S.; Lee, K. W.; Kweon, Jin Jung; Lee, Cheol Eui; Kim, K.; Lee, J.; Noh, S. J.; Kim, H. S.

doi:10.1063/1.3310012

Cited by 7 publications

(4 citation statements)

References 23 publications

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“…We hypothesize that heterogeneously delithiating a single plane can induce a larger effect, than was previously calculated for homogeneous delithiation by Wu and Zhang . Results of Li NMR indicate that these point defects are heterogeneously distributed, suggesting that this hypothesis is reasonable. Calculations similar to those in Ref.…”

Section: Resultsmentioning

confidence: 48%

The effect of electrochemical cycling on the strength of LiCoO₂

Lin

Zhao

et al. 2018

J Am Ceram Soc

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This work utilizes in situ transmission electron microscopy-based nanopillar compression to investigate the effect of electrochemical cycling on the mechanical properties of LiCoO 2 . The ultimate strength of LiCoO 2 in the pristine state, and after 1 and 11 cycles are 5.62 ± 0.22 GPa, 3.91 ± 1.22 GPa, and 2.27 ± 1.07 GPa, respectively. The reduced average yield strengths and the large standard deviations of cycled samples, relative to the pristine powder, are hypothesized to result from nonuniform accumulation of Li + site-point defects during cycling; either H + or Li + vacancies. Density functional theory calculations support our hypothesized link between a nonuniform Li site-point defect distribution in the cathode and reduction in the materials cohesive strength. K E Y W O R D S electrodes, lithium oxide, mechanical properties

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Section: Resultsmentioning

confidence: 48%

The effect of electrochemical cycling on the strength of LiCoO₂

Lin

Zhao

et al. 2018

J Am Ceram Soc

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“…Here, we compare the present LCO result with those for Na 1−y CoO 2 , which has a similar structure to that for LCO. Based on χ and 23 Na-NMR measurements on NaCoO 2 (NCO) [40], Co 3+ ions are reported to be a nonmagnetic S = 0 (t 6 2g ) state in the T range between ß25 and 300 K. This was confirmed by μSR [41]. Thus, the past data suggest the absence of nonordered magnetism or spin fluctuation in NaCoO 2 [40,41].…”

Section: Origin Of Nonordered Magnetism At Ambient Temperaturementioning

confidence: 84%

“…Although Artemenko et al [15] reported an EPR signal with g = 2.16 for VST-LCO, probably due to the Li + -O − PM centers; such an EPR signal is observed only below ß30 K with H pp 110 Oe. Kim et al [23] reported the EPR signal with g 2.16 at ambient temperature for the compound prepared by a molten salt method with x 0 = 7. However, their LCO compound is most likely quite different from a typical ST-LCO and OST-LCO based on their electrochemical data, such as a large hysteresis between the charge and discharge curve and a small Q dis value (<100 mAh•g −1 ) in the voltage range between 2.8 and 4.2 V [23].…”

Section: B Electron Paramagnetic Resonancementioning

confidence: 99%

Thermally activated spin fluctuations in stoichiometric LiCoO2clarified by electron paramagnetic resonance and muon-spin rotation and relaxation measurements

et al. 2014

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Lithium cobalt dioxide (LiCoO 2) belongs to a family of layered CoO 2-based materials and has considerable interests in both fundamental physics and technological applications in lithium-ion batteries. We report the results of structural, electrochemical, magnetic susceptibility (χ), electron paramagnetic resonance (EPR), and muon-spin rotation and relaxation (μSR) measurements on powder Li x 0 CoO 2 samples, where the nominal Li/Co ratios (x 0) were 0.95, 1.00, 1.02, 1.05, and 1.10, respectively. Structural, electrochemical, and χ measurements suggested that the sample with x 0 = 1.02 is very close to single stoichiometric LiCoO 2 (ST-LCO) phase and that the Co ions in the x 0 = 1.02 sample are in a nonmagnetic low-spin state with S = 0 (t 6 2g). However, both EPR and μSR revealed that the x 0 = 1.02 (ST-LCO) sample includes a large amount of nonordered magnetic phase in the temperature (T) range between 100 and 500 K. The volume fraction of such magnetic phase was found to be ß45 vol% at 300 K by μSR, indicating an intrinsic bulk feature for ST-LCO. In fact, structural and photoelectron spectroscopic analyses clearly excluded the possibility that the nonordered magnetism is caused by impurities, defects, or surfaces. Because EPR and μSR sense static and dynamic nature of local magnetic environments, we concluded that Co spins in ST-LCO are fluctuating in the EPR and μSR time-windows. We also proposed possible origins of such nonordered magnetism, that is, a spin-state transition and charge disproportionation.

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“…Studies have shown that after plasma treatment of cancer cells, cytochrome c was released [ 20 ] and the expression of NOXA, [ 21 ] Bax, [ 22 ] caspase 9, [ 23 ] and caspase 3/7 [ 20,24–26 ] was increased. Additionally, loss of mitochondrial membrane potential [ 20,25,27–29 ] and induction of DNA fragmentation [ 30 ] after plasma treatment were observed in some studies. In summary, cancer cells treated by CAP follow DNA damage pathways [ 31,32 ] as well as apoptosis pathways.…”

Section: Introductionmentioning

confidence: 99%

Direct cold atmospheric plasma and plasma‐activated medium effects on breast and cervix cancer cells

Jezeh

Tayebi

Khani

et al. 2020

Plasma Processes & Polymers

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In this study, the effects of cold plasma and plasma-activated medium (PAM) are investigated through different treatment times, different intervals between treatment and analysis, and synthesis of helium gas and helium + 0.5% oxygen. The viability of two cancer cell lines including Hela and MDA-MB-231, which are related to cervix and breast cancers, respectively, is investigated using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide assay. To study the effect of plasma on normal cells, the corresponding method is used for examination of the normal human fibroblasts. H 2 O 2 showed a higher concentration after direct-plasma treatment than PAM treatment. Caspase 3, caspase 8, and Bax proteins and the relative Bax/Bcl-2 ratio are compared in both the direct-plasma and PAM methods. The results show that the expression level of apoptotic proteins caspase 3 and caspase 8 in direct-plasma treatment is higher than that in PAM treatment, and the level of relative Bcl-2/Bax ratio is increased, demonstrating the induction of the apoptosis mechanism.

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Structural defects in LiCoO2 studied by L7i nuclear magnetic relaxation

Cited by 7 publications

References 23 publications

The effect of electrochemical cycling on the strength of LiCoO₂

The effect of electrochemical cycling on the strength of LiCoO₂

Thermally activated spin fluctuations in stoichiometric LiCoO2clarified by electron paramagnetic resonance and muon-spin rotation and relaxation measurements

Direct cold atmospheric plasma and plasma‐activated medium effects on breast and cervix cancer cells

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Structural defects in LiCoO2 studied by L7i nuclear magnetic relaxation

Cited by 7 publications

References 23 publications

The effect of electrochemical cycling on the strength of LiCoO2

The effect of electrochemical cycling on the strength of LiCoO2

Thermally activated spin fluctuations in stoichiometric LiCoO2clarified by electron paramagnetic resonance and muon-spin rotation and relaxation measurements

Direct cold atmospheric plasma and plasma‐activated medium effects on breast and cervix cancer cells

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The effect of electrochemical cycling on the strength of LiCoO₂

The effect of electrochemical cycling on the strength of LiCoO₂