Applications of ESCA to polymer chemistry. XVII. Systematic investigation of the core levels of simple homopolymers

Clark, D. T.; Thomas, H. R.

doi:10.1002/pol.1978.170160407

Cited by 279 publications

(140 citation statements)

References 29 publications

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“…The third sub-peak at ≈288.3 eV can be assigned to a carbon doubly bound to oxygen or singly bound to two oxygen atoms, or to fluorinated alkyl carbonate (R-CF 2 -C * H 2 -O-CO 2 -R). 38 The third sub-peak for the coated electrode cycled in LiClO 4 is again at a higher binding energy (≈288.8 eV), which can be related to a carboxylic chemistry. The final sub-peak at ≈293.1 eV is assigned to CF 3 chemistries.…”

Section: Resultsmentioning

confidence: 99%

XPS Investigation of the Electrolyte Induced Stabilization of LiCoO₂and “AlPO₄”-Coated LiCoO₂Composite Electrodes

Quinlan

Kwabi

et al. 2015

J. Electrochem. Soc.

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The "AlPO 4 " coating has been shown to improve the electrochemical performance of LiCoO 2 batteries. We previously showed that the "AlPO 4 " coating promotes the formation of metal fluorides, which could act as a stable surface film and protect LiCoO 2 from continuous degradation upon cycling. In this work, we removed the fluorine source in the LiPF 6 salt by using the LiClO 4 salt and investigated the effectiveness of the "AlPO 4 " coating. Interestingly, the "AlPO 4 " coating was found to improve the voltage efficiency and capacity retention when cycling in the LiPF 6 electrolyte, but was detrimental when cycling in the LiClO 4 electrolyte. XPS revealed that the "AlPO 4 " coating promotes the formation of metal fluoride in both electrolytes, with the surface film formed in LiClO 4 being more electrically resistive compared to that formed in LiPF 6 . The source of fluorine in the coated electrode cycled in LiPF 6 is largely attributed to the LiPF 6 salt whereas the source of fluorine in the coated electrode cycled in LiClO 4 is the binder PVDF. We believe that the coating could react with HF impurity in the LiPF 6 electrolyte or from the binder PVDF and form stable metal fluoride films on the surface. Lithium cobalt oxide, LiCoO 2 , is currently the most common cathode material used in lithium ion battery technology, 1,2 but only half of the theoretical capacity, ≈140 mA h g −1 , is obtained when charged to 4.2 V vs. Li + /Li. Higher capacity is obtainable if cycled to voltages greater than 4.2 V, but this was shown to result in high capacity loss.3,4 Structural instability 3,5 and reactivity of the cathode with the electrolyte 3 have both been proposed as possible mechanisms for the observed capacity fade. Surface modification via coatings with intrinsic materials by thermal treatment during the synthesis process 6 or with extrinsic materials, 7-10 is one successful method of improving performance. These cathodes with surface-modified LiCoO 2 1,2,6-11 have shown improvement when cycled to high voltages compared to bare LiCoO 2 positive electrodes. However, the origin responsible for the increased performance is not well understood. Understanding the mechanism responsible for the enhancement in cycling stability provided by the coatings/surface modification is essential to further stabilize positive electrode materials for applications that demand high cycle life such as electrical vehicles and stationary storage.Enhanced performance in cycling associated with surface coating has been attributed to phase transitions, 3,4,[12][13][14][15] The recent investigation by Dahèron et al.,18 showed that the substitution of Al for Co not only increases the ionic nature of the Co-O bond through orbital mixing, but also that the substitution reduces the basicity of the LiCoO 2 surface, thus making the surface less receptive or vulnerable to acidic attack in the electrolyte. However, this benefit can be temporary as recent work indicates that the Li-Al-Co-O surface region is consumed during cycling. 27 The "AlPO 4 "-coati...

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Section: Resultsmentioning

confidence: 99%

XPS Investigation of the Electrolyte Induced Stabilization of LiCoO₂and “AlPO₄”-Coated LiCoO₂Composite Electrodes

Quinlan

Kwabi

et al. 2015

J. Electrochem. Soc.

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“…The peaks around 532 and 533.4eV are clearly from carbon-oxygen groups. In the pioneering work of Clark et al [87,88], the O1s and C1s binding energy shifts are evaluated for a range of homo polymers and organic molecules. They found mainly four groups for the O1s within a range of ~2.5 eV.…”

Section: X-ray Photoelectron Spectroscopymentioning

confidence: 99%

Analysis of the structure and chemical properties of some commercial carbon nanostructures

Tessonnier

Rosenthal

Hansen

et al. 2009

Carbon

316

256

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For many years the scientific community has believed in a promising future for carbon nanotubes for various applications in such diverse fields as polymer reinforcement, adsorption, catalysis, electronics and medicine. Industrial production of carbon nanotubes and -fibers and the subsequent availability and decrease of price, have rendered this vision feasible. In the last years, several carbon nanomaterial products have been marketed by major chemical companies. In this work, we present an extensive characterization of a representative set of commercially available carbon nanomaterials. Special focus has been put on their quality, i.e. presence of metal or carbonaceous impurities but also homogeneity and structural integrity. The observations are of importance for subsequent use in catalysis where the presence of impurities or defects in the nanostructure can dramatically modify the activity of the catalytic material..

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“…Surface analysis of ESCA The photoelectron spectra for MAA-grafted PTFE, LDPE, and HDPE (grafted PTFE, LDPE, PMAA, and HDPE) plates were recorded on a Shimadzu ESCA-type spectroscopy with MgKa (1253.6 eV) operating at 8 kV and 30 mA, [6,7] and the intensity ratios, 01 s/C 1 s and Fis/Cis, were calculated from the individual peak areas and ionized cross-sections. [14][15][16] 2.3.2. Contact angle measurements As a measure of the wettabilities, contact angles for water on the grafted samples prepared in this study were estimated with a sessile drop method at 25 °C under an atmosphere of saturated water vapor using a Kyowa Kagaku TYP-QI-type goniometer.…”

Section: Plasma Treatment and Photograftingmentioning

confidence: 99%

Surface Modification and Autohesive Properties of Poly(tetrafluoroethylene) and Polyethylene by the Photografting Technique.

Yamada

Kimura

Hirata

1998

J. Photopol. Sci. Technol.

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Poly(tetrafluoroethylene) (PTFE) and low and high density polyethylene (LDPE and HDPE) plates were surface-modified by the photogafting of methacrylic acid (MAA) using a 400 W high pressure mercury lamp. The autohesive strengths for MAA-graftedPTFE, LDPE and HDPE plates were estimated from the tensile shear strength measurements and their autohesive properties were discussed in relation to surface and bulk properties of the grafted layers formed on their substrates.The contact angles which were related with the wettabilities of the modified surfaces increased with an increase in the grafted amount, and then leveled off when the surfaces were wholly covered with grafted PMAA chains.The wettabilities for grafted PTFE plates were improved at a considerably low grafted amount, since the photografting of MAA onto the PTFE plates was most restricted to the outer surface region among the three types of substrates used in this study. The grafted LDPE and HDPE plates possessed high water-absorptivities. The autohesive strengths for graftedPTFE plates immersed in water reached the value equivalent to their adhesive ones.For the gratedPTFE plates immersed in an aqueous HCl solution of pH 3 in place of water, the autohesive strength sharply inch in the range of lower grafted amounts.These results suggest that an increase in the autohesive strength can be caused not only by the entanglements of graftedPMAA chains but also by the formation of hydrogen bonding between carboxyl groups affixed to the grafted PMAA chains. On the other hand, in the case of the autohesive strength measurements for graftedLDPE and HDPE plates, the substrate breaking occurred at higher grafted amounts. The grafted amount at which the substrate failed for grafted HDPE plates was lower than that for grafted LDPE plate because the photografting onto the HDPE plates was more restricted to the outer surface region.It was made clear that the autohesive strength for grafted PTFE plates reached the value equivalent to the autohesive strength and the autohesive strengths for graftedLDPE and HDPE plates exceeded the ultimate tensile strength by heat pressing the grafted samples with the grafted layers swollen in water.

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Applications of ESCA to polymer chemistry. XVII. Systematic investigation of the core levels of simple homopolymers

Cited by 279 publications

References 29 publications

XPS Investigation of the Electrolyte Induced Stabilization of LiCoO₂and “AlPO₄”-Coated LiCoO₂Composite Electrodes

XPS Investigation of the Electrolyte Induced Stabilization of LiCoO₂and “AlPO₄”-Coated LiCoO₂Composite Electrodes

Analysis of the structure and chemical properties of some commercial carbon nanostructures

Surface Modification and Autohesive Properties of Poly(tetrafluoroethylene) and Polyethylene by the Photografting Technique.

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Applications of ESCA to polymer chemistry. XVII. Systematic investigation of the core levels of simple homopolymers

Cited by 279 publications

References 29 publications

XPS Investigation of the Electrolyte Induced Stabilization of LiCoO2and “AlPO4”-Coated LiCoO2Composite Electrodes

XPS Investigation of the Electrolyte Induced Stabilization of LiCoO2and “AlPO4”-Coated LiCoO2Composite Electrodes

Analysis of the structure and chemical properties of some commercial carbon nanostructures

Surface Modification and Autohesive Properties of Poly(tetrafluoroethylene) and Polyethylene by the Photografting Technique.

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Product

Resources

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XPS Investigation of the Electrolyte Induced Stabilization of LiCoO₂and “AlPO₄”-Coated LiCoO₂Composite Electrodes

XPS Investigation of the Electrolyte Induced Stabilization of LiCoO₂and “AlPO₄”-Coated LiCoO₂Composite Electrodes