The Experts below are selected from a list of 1563 Experts worldwide ranked by ideXlab platform
Xianming Wang - One of the best experts on this subject based on the ideXlab platform.
-
High-Concentration Trimethyl Phosphate-Based Nonflammable Electrolytes with Improved Charge–Discharge Performance of a Graphite Anode for Lithium-Ion Cells
Journal of The Electrochemical Society, 2006Co-Authors: Xianming Wang, Chisa Yamada, Hitoshi Naito, Go Segami, Koichi KibeAbstract:We developed Trimethyl Phosphate (TMP)-based nonflammable electrolytes with a high TMP content exceeding 70% to increase the safety of lithium-ion cells with a graphite anode. TMP exhibits good oxidation stability and poor reduction stability at the graphite anode; therefore, we focused our efforts on suppressing TMP reduction decomposition at the graphite anode during charging. We selected a graphite material, named STG, with a surface partly coated by amorphous carbon particles to improve the TMP reduction stability. A new ternary mixed additive, 2 wt % vinylene carbonate +8 wt % vinyl ethylene carbonate +2 wt % cyclo hexane, was developed to exert a synergistic effect to improve the charge-discharge performance of the STG anode in TMP-based electrolytes. We further found that a high-concentration lithium bisperfluoroethylsulfonyl imide [LiN(SO 2 C 2 F 5 ) 2 ], of 2 mol dm - 3 was effective for suppressing TMP decomposition at the STG anode surface. Consequently, we were able to realize excellent cycling performance of an STG anode with over 70% TMP nonflammable electrolytes by applying the above approaches. This is the first report of such excellent performance of a graphite anode with high-content TMP-based nonflammable electrolytes.
-
high concentration Trimethyl Phosphate based nonflammable electrolytes with improved charge discharge performance of a graphite anode for lithium ion cells
Journal of The Electrochemical Society, 2006Co-Authors: Xianming Wang, Chisa Yamada, Hitoshi Naito, Go Segami, Koichi KibeAbstract:We developed Trimethyl Phosphate (TMP)-based nonflammable electrolytes with a high TMP content exceeding 70% to increase the safety of lithium-ion cells with a graphite anode. TMP exhibits good oxidation stability and poor reduction stability at the graphite anode; therefore, we focused our efforts on suppressing TMP reduction decomposition at the graphite anode during charging. We selected a graphite material, named STG, with a surface partly coated by amorphous carbon particles to improve the TMP reduction stability. A new ternary mixed additive, 2 wt % vinylene carbonate +8 wt % vinyl ethylene carbonate +2 wt % cyclo hexane, was developed to exert a synergistic effect to improve the charge-discharge performance of the STG anode in TMP-based electrolytes. We further found that a high-concentration lithium bisperfluoroethylsulfonyl imide [LiN(SO 2 C 2 F 5 ) 2 ], of 2 mol dm - 3 was effective for suppressing TMP decomposition at the STG anode surface. Consequently, we were able to realize excellent cycling performance of an STG anode with over 70% TMP nonflammable electrolytes by applying the above approaches. This is the first report of such excellent performance of a graphite anode with high-content TMP-based nonflammable electrolytes.
-
nonflammable Trimethyl Phosphate solvent containing electrolytes for lithium ion batteries ii the use of an amorphous carbon anode
Journal of The Electrochemical Society, 2001Co-Authors: Xianming Wang, Eiki Yasukawa, Shigeaki KasuyaAbstract:In order to improve the cycling performance of lithium-ion hatteries with nonflammable Trimethyl Phosphate (TMP)-based electrolytes, amorphous carbon (AC) was used as the anode material. It was found that the reduction decomposition of TMP solvent, which occurred without limit on a natural graphite anode and concomitantly generated a large amount of methane (CH 4 ) and ethylene (C 2 H 4 ) gases, was considerably suppressed on amorphous carbon anode. This improvement was attributed to the disordered structure of amorphous carbon, which hindered the cointercalation of TMP solvent. The charge/discharge result and cyclic voltammetry further disclosed that a highly stable and passivating surface film, called the solid electrolyte interphase film, was formed on the AC surface at the potential near I V. As a result, an AC/LiCoO 2 ion cell with I mol/dm 3 LiPF 6 /ethylene carbonate (EC) + propylene carbonate (PC) + diethylcarbonate (DEC) + TMP (30:30:20:20) nonflammable electrolyte exhibited promising cycling performance. Furthermore, this electrolyte was also found to have good low-temperature performance with the freezing point of < 40°C. Thermal test results disclosed that a lithium-ion cell with 1 mol/dm 3 LiPF 6 /EC + PC + DEC + TMP (30:30:20:20) exhibited good thermal stability.
-
nonflammable Trimethyl Phosphate solvent containing electrolytes for lithium ion batteries i fundamental properties
Journal of The Electrochemical Society, 2001Co-Authors: Xianming Wang, Eiki Yasukawa, Shigeaki KasuyaAbstract:To develop nonflammable electrolytes for lithium-ion batteries, the fundamental properties of Trimethyl Phosphate (TMP)-based electrolytes with LiPF 6 as solute were investigated for natural graphite anode and LiCoO 2 cathodes, It was found that the TMP solvent had good oxidation stability and poor reduction stability, which led to TMP reduction decomposition on the natural graphite electrode at the negative potential of 1.2 V. To solve this problem, ethylene carbonate (EC). propylene carbonate (PC), and diethyl carbonate (DEC) cosolvents were mixed with TMP solvent. As a result, the reduction decomposition of the TMP solvent was considerably suppressed in < 10% TMP containing EC + PC + TMP and <25% TMP containing EC + DEC + TMP electrolytes due to the formation of good solid electrolyte interphase film on natural graphite electrode in these two mixed electrolytes. The nonflammability of the TMP electrolyte declined with mixing flammable cosolvents, which was explained by a flame retarding mechanism involving a hydrogen radical trap in the gas phase. According to this mechanisms it was deduced that the cosolvents with high boiling point and fewer hydrogen atoms were promising for nonflammability of mixed electrolytes Furthermore, a thermal test disclosed that the thermal stability of lithium-ion cells may be improved by using TMP-containing electrolytes.
-
Nonflammable Trimethyl Phosphate Solvent-Containing Electrolytes for Lithium-Ion Batteries: I. Fundamental Properties
Journal of The Electrochemical Society, 2001Co-Authors: Xianming Wang, Eiki Yasukawa, Shigeaki KasuyaAbstract:To develop nonflammable electrolytes for lithium-ion batteries, the fundamental properties of Trimethyl Phosphate (TMP)-based electrolytes with LiPF 6 as solute were investigated for natural graphite anode and LiCoO 2 cathodes, It was found that the TMP solvent had good oxidation stability and poor reduction stability, which led to TMP reduction decomposition on the natural graphite electrode at the negative potential of 1.2 V. To solve this problem, ethylene carbonate (EC). propylene carbonate (PC), and diethyl carbonate (DEC) cosolvents were mixed with TMP solvent. As a result, the reduction decomposition of the TMP solvent was considerably suppressed in < 10% TMP containing EC + PC + TMP and
Shigeaki Kasuya - One of the best experts on this subject based on the ideXlab platform.
-
nonflammable Trimethyl Phosphate solvent containing electrolytes for lithium ion batteries ii the use of an amorphous carbon anode
Journal of The Electrochemical Society, 2001Co-Authors: Xianming Wang, Eiki Yasukawa, Shigeaki KasuyaAbstract:In order to improve the cycling performance of lithium-ion hatteries with nonflammable Trimethyl Phosphate (TMP)-based electrolytes, amorphous carbon (AC) was used as the anode material. It was found that the reduction decomposition of TMP solvent, which occurred without limit on a natural graphite anode and concomitantly generated a large amount of methane (CH 4 ) and ethylene (C 2 H 4 ) gases, was considerably suppressed on amorphous carbon anode. This improvement was attributed to the disordered structure of amorphous carbon, which hindered the cointercalation of TMP solvent. The charge/discharge result and cyclic voltammetry further disclosed that a highly stable and passivating surface film, called the solid electrolyte interphase film, was formed on the AC surface at the potential near I V. As a result, an AC/LiCoO 2 ion cell with I mol/dm 3 LiPF 6 /ethylene carbonate (EC) + propylene carbonate (PC) + diethylcarbonate (DEC) + TMP (30:30:20:20) nonflammable electrolyte exhibited promising cycling performance. Furthermore, this electrolyte was also found to have good low-temperature performance with the freezing point of < 40°C. Thermal test results disclosed that a lithium-ion cell with 1 mol/dm 3 LiPF 6 /EC + PC + DEC + TMP (30:30:20:20) exhibited good thermal stability.
-
nonflammable Trimethyl Phosphate solvent containing electrolytes for lithium ion batteries i fundamental properties
Journal of The Electrochemical Society, 2001Co-Authors: Xianming Wang, Eiki Yasukawa, Shigeaki KasuyaAbstract:To develop nonflammable electrolytes for lithium-ion batteries, the fundamental properties of Trimethyl Phosphate (TMP)-based electrolytes with LiPF 6 as solute were investigated for natural graphite anode and LiCoO 2 cathodes, It was found that the TMP solvent had good oxidation stability and poor reduction stability, which led to TMP reduction decomposition on the natural graphite electrode at the negative potential of 1.2 V. To solve this problem, ethylene carbonate (EC). propylene carbonate (PC), and diethyl carbonate (DEC) cosolvents were mixed with TMP solvent. As a result, the reduction decomposition of the TMP solvent was considerably suppressed in < 10% TMP containing EC + PC + TMP and <25% TMP containing EC + DEC + TMP electrolytes due to the formation of good solid electrolyte interphase film on natural graphite electrode in these two mixed electrolytes. The nonflammability of the TMP electrolyte declined with mixing flammable cosolvents, which was explained by a flame retarding mechanism involving a hydrogen radical trap in the gas phase. According to this mechanisms it was deduced that the cosolvents with high boiling point and fewer hydrogen atoms were promising for nonflammability of mixed electrolytes Furthermore, a thermal test disclosed that the thermal stability of lithium-ion cells may be improved by using TMP-containing electrolytes.
-
Nonflammable Trimethyl Phosphate Solvent-Containing Electrolytes for Lithium-Ion Batteries: I. Fundamental Properties
Journal of The Electrochemical Society, 2001Co-Authors: Xianming Wang, Eiki Yasukawa, Shigeaki KasuyaAbstract:To develop nonflammable electrolytes for lithium-ion batteries, the fundamental properties of Trimethyl Phosphate (TMP)-based electrolytes with LiPF 6 as solute were investigated for natural graphite anode and LiCoO 2 cathodes, It was found that the TMP solvent had good oxidation stability and poor reduction stability, which led to TMP reduction decomposition on the natural graphite electrode at the negative potential of 1.2 V. To solve this problem, ethylene carbonate (EC). propylene carbonate (PC), and diethyl carbonate (DEC) cosolvents were mixed with TMP solvent. As a result, the reduction decomposition of the TMP solvent was considerably suppressed in < 10% TMP containing EC + PC + TMP and
Lars Österlund - One of the best experts on this subject based on the ideXlab platform.
-
Adsorption of Trimethyl Phosphate and triethyl Phosphate on dry and water pre-covered hematite, maghemite, and goethite nanoparticles.
Journal of colloid and interface science, 2012Co-Authors: Peter Mäkie, Per Persson, Lars ÖsterlundAbstract:Adsorption of Trimethyl Phosphate (TMP) and triethyl Phosphate (TEP) on well-characterized nanoparticles of hematite (α-Fe(2)O(3)), maghemite (γ-Fe(2)O(3)), and goethite (α-FeOOH) has been studied by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), 2D correlation DRIFTS analysis, and X-ray photoelectron spectroscopy (XPS) on dry and water pre-covered surfaces. It is shown that, at room temperature and low coverage, both TMP and TEP coordinate to Lewis acid Fe sites through the O phosphoryl atom on hematite and maghemite, while hydrogen bonding to Bronstedt acid surface OH groups dominates on goethite. At room temperature, slow dissociation of TMP occurs on the iron (hydr)oxide nanoparticles, whereby a methoxy group is displaced to form surface methoxy, leaving adsorbed dimethyl Phosphate (DMP). Methoxy is further decomposed to formate, suggesting an oxidative degradation pathway in synthetic air on the oxide particles. Relatively, larger amounts of DMP and surface methoxy form on maghemite, while more formate is produced on hematite. Upon TMP adsorption on dry goethite nanoparticles, no oxidation surface products were detected. Instead, a slow TMP hydrolysis pathway is observed, yielding orthoPhosphate. It is found that pre-adsorbed water stimulates the hydrolysis of TMP. In contrast to TMP, TEP adsorbs molecularly on all iron hydr(oxide) nanoparticles. This is attributed to the longer aliphatic chain, which stabilizes the loss of charge on the methoxy CO bonds by charge redistribution upon phosphoryl O coordination to Fe surface atoms. The presented results implicate different reactivity depending on specific molecular structure of the organophosphorus compound (larger functional groups can compensate loss of charge due to surface coordination) and iron (hydr)oxide surface structure (exposing Lewis acid or Bronstedt acid sites).
-
Solar Light Degradation of Trimethyl Phosphate and Triethyl Phosphate on Dry and Water-Precovered Hematite and Goethite Nanoparticles
The Journal of Physical Chemistry C, 2012Co-Authors: Peter Mäkie, Per Persson, Lars ÖsterlundAbstract:We report on the solar-light-mediated degradation of Trimethyl Phosphate (TMP) and triethyl Phosphate (TEP) on hematite and goethite nanoparticles in synthetic air. Adsorption and photoreactions of ...
-
Adsorption of Trimethyl Phosphate on Maghemite, Hematite, and Goethite Nanoparticles
The journal of physical chemistry. A, 2011Co-Authors: Peter Mäkie, Per Persson, Gunnar Westin, Lars ÖsterlundAbstract:Adsorption of Trimethyl Phosphate (TMP) on well-characterized hematite, maghemite and goethite nanopartides was studied by in situ DRIFT spectroscopy as a model system for adsorption of organophosphorous (OP) compounds on iron minerals. The iron minerals were characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), specific surface area, and pore size distribution. The minerals were found to consist of stoichimetrically and morphologically well-defined maghemite, hematite, and goethite nanoparticles. Analysis of in situ diffuse reflectance Fourier transform (DRIFT) spectroscopy shows that TMP bonds mainly to Lewis acid Fe sites through the O phosphoryl atom (-P=O-Fe) on hematite and maghemite. On goethite most TMP molecules bond to Bronstedt acid surface OH groups and form hydrogen bonded surface complexes. The vibrational mode analysis and uptake kinetics suggest two main reasons for the observed trend of reactivity toward TMP (hematite > maghemite > goethite): (i) larger number of accessible Lewis acid adsorption sites on hematite; (ii) stronger interaction between the Lewis acid Fe sites and the phosphoryl O atom on TAP for hematite and maghemite compared to goethite with concomitant formation of surface coordinated TMP and dimethyl Phosphate intermediates. As a result, on the oxides a surface oxidation pathway dominates during the initial adsorption, which results in the formation of surface methoxy and formate. In contrast, on goethite a slower hydrolysis pathway is identified, which eventually yields phosphoric acid. The observed trends of the reactivity and analysis of the corresponding surface structure and particle morphology suggest an intimate relation between the surface chemistry of exposed crystal facets on the iron minerals. These results are important to understand OP surface chemistry on iron minerals.
Stephen F. Previs - One of the best experts on this subject based on the ideXlab platform.
-
Gas Chromatography–Mass Spectrometry Assay of the 18O Enrichment of Water as Trimethyl Phosphate
Analytical biochemistry, 2002Co-Authors: Daniel Z. Brunengraber, Brendan J. Mccabe, Jill Katanik, Stephen F. PrevisAbstract:We have developed an assay for determining the 18O enrichment of water in biological fluids. Urine, plasma, or whole blood is reacted with phosphorous pentachloride to yield phosphoric acid. Derivatization of phosphoric acid with diazomethane generates Trimethyl Phosphate. The enrichment of Trimethyl Phosphate is nearly four times that of water and is assayed using gas chromatography-mass spectrometry (electron impact ionization). Yang et al. (1998, Anal. Biochem. 258, 315-321) assayed the 2H enrichment of body water after exchange with acetone, by gas chromatography-mass spectrometry. The combination of our 18O method and the 2H method of Yang et al. allows one to measure energy expenditure via "doubly labeled" water (2H(2)O + H(2)18O), using small samples of body fluids. These techniques were used to measure energy expenditure in mice, in which the 18O enrichment of body water can be monitored down to 0.025%.
-
gas chromatography mass spectrometry assay of the 18o enrichment of water as Trimethyl Phosphate
Analytical Biochemistry, 2002Co-Authors: Daniel Z. Brunengraber, Brendan J. Mccabe, Jill Katanik, Stephen F. PrevisAbstract:We have developed an assay for determining the 18O enrichment of water in biological fluids. Urine, plasma, or whole blood is reacted with phosphorous pentachloride to yield phosphoric acid. Derivatization of phosphoric acid with diazomethane generates Trimethyl Phosphate. The enrichment of Trimethyl Phosphate is nearly four times that of water and is assayed using gas chromatography-mass spectrometry (electron impact ionization). Yang et al. (1998, Anal. Biochem. 258, 315-321) assayed the 2H enrichment of body water after exchange with acetone, by gas chromatography-mass spectrometry. The combination of our 18O method and the 2H method of Yang et al. allows one to measure energy expenditure via "doubly labeled" water (2H(2)O + H(2)18O), using small samples of body fluids. These techniques were used to measure energy expenditure in mice, in which the 18O enrichment of body water can be monitored down to 0.025%.
Koichi Kibe - One of the best experts on this subject based on the ideXlab platform.
-
High-Concentration Trimethyl Phosphate-Based Nonflammable Electrolytes with Improved Charge–Discharge Performance of a Graphite Anode for Lithium-Ion Cells
Journal of The Electrochemical Society, 2006Co-Authors: Xianming Wang, Chisa Yamada, Hitoshi Naito, Go Segami, Koichi KibeAbstract:We developed Trimethyl Phosphate (TMP)-based nonflammable electrolytes with a high TMP content exceeding 70% to increase the safety of lithium-ion cells with a graphite anode. TMP exhibits good oxidation stability and poor reduction stability at the graphite anode; therefore, we focused our efforts on suppressing TMP reduction decomposition at the graphite anode during charging. We selected a graphite material, named STG, with a surface partly coated by amorphous carbon particles to improve the TMP reduction stability. A new ternary mixed additive, 2 wt % vinylene carbonate +8 wt % vinyl ethylene carbonate +2 wt % cyclo hexane, was developed to exert a synergistic effect to improve the charge-discharge performance of the STG anode in TMP-based electrolytes. We further found that a high-concentration lithium bisperfluoroethylsulfonyl imide [LiN(SO 2 C 2 F 5 ) 2 ], of 2 mol dm - 3 was effective for suppressing TMP decomposition at the STG anode surface. Consequently, we were able to realize excellent cycling performance of an STG anode with over 70% TMP nonflammable electrolytes by applying the above approaches. This is the first report of such excellent performance of a graphite anode with high-content TMP-based nonflammable electrolytes.
-
high concentration Trimethyl Phosphate based nonflammable electrolytes with improved charge discharge performance of a graphite anode for lithium ion cells
Journal of The Electrochemical Society, 2006Co-Authors: Xianming Wang, Chisa Yamada, Hitoshi Naito, Go Segami, Koichi KibeAbstract:We developed Trimethyl Phosphate (TMP)-based nonflammable electrolytes with a high TMP content exceeding 70% to increase the safety of lithium-ion cells with a graphite anode. TMP exhibits good oxidation stability and poor reduction stability at the graphite anode; therefore, we focused our efforts on suppressing TMP reduction decomposition at the graphite anode during charging. We selected a graphite material, named STG, with a surface partly coated by amorphous carbon particles to improve the TMP reduction stability. A new ternary mixed additive, 2 wt % vinylene carbonate +8 wt % vinyl ethylene carbonate +2 wt % cyclo hexane, was developed to exert a synergistic effect to improve the charge-discharge performance of the STG anode in TMP-based electrolytes. We further found that a high-concentration lithium bisperfluoroethylsulfonyl imide [LiN(SO 2 C 2 F 5 ) 2 ], of 2 mol dm - 3 was effective for suppressing TMP decomposition at the STG anode surface. Consequently, we were able to realize excellent cycling performance of an STG anode with over 70% TMP nonflammable electrolytes by applying the above approaches. This is the first report of such excellent performance of a graphite anode with high-content TMP-based nonflammable electrolytes.
