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1.
Spherical LiNi1/2Mn1/2O 2 powders were synthesized from LiOH . H2O and coprecipitated metal hydroxide, (Ni1/2Mn1/2)(OH)2. The average particle size of the powders was about 10 m and the size distribution was quite narrow due to the homogeneity of the metal hydroxide, (Ni1/2Mn1/2)(OH)2. The tap-density of the LiNi1/2Mn1/2O2 powders was approximately 2.2 g cm–3, which is comparable to the tap-density of commercial LiCoO2. The LiNi1/2Mn1/2 O2electrode delivered a discharge capacity of 152, 163, 183, and 189 mA h g–1 in the voltage ranges of 2.8–4.3, 2.8–4.4, 2.8–4.5, and 2.8–4.6 V, respectively, with good cyclability. Furthermore, Al(OH)3-coated LiNi1/2Mn1/2O2exhibited excellent cycling behavior and rate capability compared to the pristine electrode. 相似文献
2.
Faqiang Li Guowei Yang Guofeng Jia Xuehui Shangguan Qin Zhuge Bin Bai 《Journal of Applied Electrochemistry》2017,47(11):1189-1201
3.
4.
O. V. Belyaeva T. A. Krasnova S. A. Semenova O. S. Gladkova 《Solid Fuel Chemistry》2011,45(6):418-421
The results of the modification of AG-OV-1 activated carbon under various conditions (by atmospheric oxygen at elevated temperatures
and by hydrogen peroxide or ozone) are given. The effect of the used modifier on changes in the porosity, surface state, and
adsorption capacity of activated carbon is evaluated. 相似文献
5.
V. A. Sokolov T. Ya. Malysheva M. D. Gasparyan 《Refractories and Industrial Ceramics》2008,49(2):146-148
Details are given of the synthesis and testing of flux-cast refractory materials in the alumina-rich region of the Al2O3-MgO-B2O3 system; XRD and petrography indicate that the main structure-forming phases are corundum and magnesian spinel. In subordinate
amounts there are the boroaluminate 9Al2O3·2B2O3 and the previously unknown compound 4Al2O3·MgO·2B2O3, whose composition has been established by microprobe analysis. Corrosion tests showed that three-component systems containing
magnesium and boron oxides at levels of 5–10% do not increase the corrosion resistance of refractories in molten sodium-calcium-silicate
glass and electrovacuum borosilicate glass.
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Translated from Novye Ogneupory, No. 3, pp. 161–163, March, 2008. 相似文献
6.
Core-shell nanostructures of Mn2O3@SiO2, Mn2O3@amino-functionalized silica, Mn2O3@vinyl-functionalized silica, and Mn2O3@allyl-functionalized silica were synthesized using the hydrolysis of the respective organosilane precursor over Mn2O3 nanoparticles dispersed using colloidal solutions of Tergitol and cyclohexane. The synthetic methodology used is an improvement
over the commonly used post-grafting or co-condensation method as it ensures a high density of functional groups over the
core-shell nanostructures. The high density of functional groups can be useful in immobilization of biomolecules and drugs
and thus can be used in targeted drug delivery. The high density of functional groups can be used for extraction of elements
present in trace amounts. These functionalized core-shell nanostructures were characterized using TEM, IR, and zeta potential
studies. The zeta potential study shows that the hydrolysis of organosilane to form the shell results in more number of functional
groups on it as compared to the shell formed using post-grafting method. The amino-functionalized core-shell nanostructures
were used for the immobilization of glucose and L -methionine and were characterized by zeta potential studies. 相似文献
7.
Abstract
Ce X Zr1−X O2 catalysts with different cerium content (X) (X = 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1.0) were prepared by a sol–gel method for use in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Among these catalysts, Ce0.6Zr0.4O2 was found to show the best catalytic performance. In order to enhance the acidity and basicity of Ce0.6Zr0.4O2 catalyst, Ga2O3 was supported on Ce0.6Zr0.4O2 (XGa2O3/Ce0.6Zr0.4O2 (X = 1, 5, 10, and 15)) by an incipient wetness impregnation method with a variation of Ga2O3 content (X, wt%). Effect of acidity and basicity of Ga2O3/Ce0.6Zr0.4O2 on the catalytic performance in the direct synthesis of dimethyl carbonate was investigated using NH3-TPD and CO2-TPD experiments. Experimental results revealed that both acidity and basicity of the catalysts played a key role in determining the catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Large acidity and basicity of the catalyst facilitated the formation of dimethyl carbonate. The amount of dimethyl carbonate produced over XGa2O3/Ce0.6Zr0.4O2 catalysts increased with increasing both acidity and basicity of the catalysts. Among the catalysts tested, 5Ga2O3/Ce0.6Zr0.4O2, which retained the largest acidity and basicity, showed the best catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. 相似文献8.
Hong Yan Chu Qiong Yu Lai Yan Jing Hao Yan Zhao Xiao Yun Xu 《Journal of Applied Electrochemistry》2009,39(10):2007-2013
Spinel Li4Mn5O12 was prepared by a sol–gel method. The manganese oxide and activated carbon composite (MnO2-AC) were prepared by a method in which KMnO4 was reduced by activated carbon (AC). The products were characterized by XRD and FTIR. The hybrid supercapacitor was fabricated
with Li4Mn5O12 and MnO2-AC, which were used as materials of the two electrodes. The pseudocapacitance performance of the Li4Mn5O12/MnO2-AC hybrid supercapacitor was studied in various aqueous electrolytes. Electrochemical properties of the Li4Mn5O12/MnO2-AC hybrid supercapacitor were studied by using cyclic voltammetry, electrochemical impedance measurement, and galvanostatic
charge/discharge tests. The results show that the hybrid supercapacitor has electrochemical capacitance performance. The charge/discharge
test showed that the specific capacitance of 51.3 F g−1 was obtained within potential range of 0–1.3 V at a charge/discharge current density of 100 mA g−1 in 1 mol L−1 Li2SO4 solution. The charge/discharge mechanism of Li4Mn5O12 and MnO2-AC was discussed. 相似文献
9.
F. Lian P. Axmann C. Stinner Q. G. Liu M. Wohlfahrt-Mehrens 《Journal of Applied Electrochemistry》2008,38(5):613-617
Positive electrode material LiNi1/2Mn1/2O2 was synthesized via the carbonate co-precipitation method and the hydroxide precipitation route to study the effects of the
precursor on its structural and electrochemical properties. The results of X-ray diffraction and Rietveld refinement show
that the carbonate precursor of Ni2+ and Mn2+ exhibits one phase at a pH of 8.5, while the hydroxide deposit separates into Ni(OH)2 and Mn(OH)2 phases under the same experimental conditions. LiNi1/2Mn1/2O2 material prepared from the hydroxide precursor shows 8.9% Li/Ni exchange and a large capacity loss of 11.3% in the first
10 cycles. By contrast, more uniform distribution of transition metal ions and stable Mn2+ in the carbonate precursor contribute to only 7.8% Li/Ni disorder in the obtained LiNi1/2Mn1/2O2, which delivers a reversible capacity of about 182 mAh g−1 at a current rate of 14 mA g−1 between 2.5 and 4.8 V. 相似文献
10.
Khan Malook Hamayun Khan Mutabar Shah Ihsan-Ul-Haque 《Korean Journal of Chemical Engineering》2018,35(1):12-19
Polypyrrole (PPy) and its composites with vanadium pentoxide (V2O5) were synthesized in aqueous medium by chemical oxidation polymerization using FeCl3·6H2O as an oxidant. The materials were characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffractometry (XRD), thermogravimetry analyzer (TGA), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), UV/visible spectroscopic techniques and LCR-meter. The FT-IR results confirmed the successful synthesis of PPy and PPy/V2O5 composites. The XRD study showed the amorphous and crystalline nature of PPy and PPy/V2O5 composites, respectively. The TGA analysis showed slight increase in the thermal stability of the composites. The SEM data verified the porous nature of PPy and the composites. The UV/visible spectrometry confirmed the doping of PPy in composites. The electrical properties of the materials displayed their semiconducting nature. The resistance of the samples was found to be dependent on temperature and the contents of V2O5 in the composites. 相似文献
11.
The synthesis of single-crystalline hollandite-type manganese oxides Na2-
x
Mn8O16 nanorods by a simple molten salt method is reported for the first time. The nanorods were characterized by powder X-ray diffraction,
scanning electron microscopy, transmission electron microscopy, and a superconducting quantum interference device magnetometer.
The magnetic measurements indicated that the nanorods showed spin glass behavior and exchange bias effect at low temperatures.
The low-temperature magnetic behaviors can be explained by the uncompensated spins on the surface of the nanorods. 相似文献
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13.
Zhong-Wen Liu Hyun-Seog Roh Ki-Won Jun Sang-Eon Park Taek-Yong Song 《Korean Journal of Chemical Engineering》2002,19(5):742-748
The catalytic behavior of Ni/Ce-ZrO2/θ-Al2O3 has been investigated in the partial oxidation of methane (POM) toward synthesis gas. The catalyst showed high activity and
selectivity due to the heat treatment of the support and the promotional effect of Ce-ZrO2. It is suggested that the support was stabilized through the heat treatment of γ-Al2O3 and the precoating of Ce-ZrO2, on which a protective layer was formed. Moreover, sintering of the catalyst was greatly suppressed for 24 h test. Pulse
experiments of CH4, O2 and/or CH4/O2 with a molar ratio of 2 were systematically performed over fresh, partially reduced and well reduced catalyst. Results indicate
that CH4 can be partially oxidized to CO and H2 by the reactive oxygen in complex NiOx species existing over the fresh catalyst. It is demonstrated that POM over Ni/Ce-ZrO2/θ-Al2O3 follows the pyrolysis mechanism, and both the carbonaceous materials from CH4 decomposition over metallic nickel and the reactive oxygen species present on NiOx and Ce-ZrO2 are intermediates for POM. 相似文献
14.
Yongli Cui Chao Yang Zhiheng Zhuang Mingzhen Wang Quanchao Zhuang 《Journal of Inorganic and Organometallic Polymers and Materials》2018,28(3):731-737
In this study, spheroid LiNi1/3Co1/3Mn1/3O2 (NCM111) cathode material were synthesized using LiOH with Ni0.5Co0.2Mn0.3(OH)2 precursor by a simple solid-state reaction, and characterized by X-ray diffraction and scanning electron microscopy. Electrochemical behavior of NCM111 was investigated by electrochemical impedance spectroscopy (EIS) combining with cyclic voltammogram (CV) and charge/discharge test in the 1 M LiPF6-EC:EMC electrolyte with ethylene sulfate (DTD) and methylene methanedisulfonate (MMDS) additives either singly or in combination with high cutoff voltage of 3.0–4.5 V at room temperature of 25 °C or elevated temperature of 55 °C. It was found that DTD additive can increase the initial coulombic efficiency of NCM111, and the spheroid NCM111 can obtain the maximum initial discharge capacity of 177.81 mAh/g with the 2 wt% DTD, and keep 92.29% capacity retention after 80 cycles. The MMDS additives would decrease the initial discharge capacity of the NCM111, and enhance significantly long cycle life of the NCM111 with the capacity retention of 99.23% over 80 cycles at high voltage of 4.5 V. The additive combination 2 wt% DTD?+?1 wt% MMDS was an optimal additive combination, demonstrating the 102.2% capacity retention over 80 cycles at room temperature and the 94.2% capacity retention over 70 cycles at elevated temperature of 55 °C. EIS results revealed that the additive blend of 2 wt% DTD?+?1 wt% MMDS can drastically lower the kinetics impedance and suppress the growth rate of R ct for the NCM111 electrode. 相似文献
15.
A cathode material for lithium-ion batteries–LiNi1/3Co1/3Mn1/3O2–was prepared by solution combustion synthesis and characterized by XRD, SEM, and galvanostatic charge/discharge cycling. The sample calcined at 950°C for 10 h showed best charge/discharge performance. An initial discharge capacity (C) of 150.5 mA h g–1 retained 95.7% of its value after 75 charge/discharge cycles at Ic = 14 mA g–1 (0.2C rate), Id = 70 mA g–1 (0.5C rate). 相似文献
16.
Yu. A. Bakhteeva E. V. Shalaeva I. A. Leonidov V. L. Kozhevnikov 《Glass Physics and Chemistry》2008,34(4):485-491
The conditions for preparation of Ce0.9Y0.1O2 (CYO) oxide coatings on La0.8Sr0.2MnO3 (LSM) ceramic substrates by screen printing were investigated. The CYO compound was synthesized by the pyrolysis of polymer-salt composites with the aim of producing submicron powders with a uniform size distribution. Transmission electron microscopy of the microstructure of the CYO compound synthesized with ethylene glycol revealed that the synthesis product consists of ultrafine crystalline particles with an average size of 5–15 nm. The use of CYO nanopowders made it possible to prepare rather dense single-layer coatings on LSM substrates. It was demonstrated that annealing of the coatings at high temperatures leads to the recrystallization and coarsening of particles. 相似文献
17.
The selective oxidation of hydrogen sulfide containing excess water and ammonia was studied over vanadium oxide-based catalysts.
The investigation was focused on the role of V2O5, and phase cooperation between V2O5 and Bi2O3 in this reaction. The conversion of H2S continued to decrease since V2O5 was gradually reduced by treatment with H2S. The activity of V2O5 was recovered by contact with oxygen. A strong synergistic phenomenon in catalytic activity was observed for the mechanically
mixed catalysts of V2O5 and Bi2O3. Temperature-programmed reduction (TPR) and oxidation (TPO) and two bed reaction tests were performed to explain this synergistic
effect by the reoxidation ability of Bi2O3.
This paper is dedicated to Professor Wha Young Lee on the occasion of his retirement from Seoul National University. 相似文献
18.
Synthetic spinels of the system MgO-Cr2O3-Al2O3-Fe2O3 are considered and the desirability of organizing their production for the refractory industry is demonstrated.
Translated from Novye Ogneupory, No. 6, pp. 32–35, June 2008. 相似文献
19.
G. J. Wang L. J. Fu B. Wang N. H. Zhao Y. P. Wu R. Holze 《Journal of Applied Electrochemistry》2008,38(4):579-581
20.
TiO2-Al2O3 mixed oxides with different compositions ranging from 40wt-% to 95wt-% of TiO2 were prepared by sol-gel method and impregnated with different amounts of VO x . Supports and catalysts were characterized by X-ray diffraction (XRD), physisorption, temperature preprogrammed reduction (H2-TPR), and ammonia temperature programmed desorption (NH3-TPD). TiO2 content in the support had obvious effect on the crystal structure, texture characteristic, acid property, and catalytic activity in dehydrogenation of ethylbenzene (EB) with carbon dioxide. The highest catalytic activity was acquired when the TiO2 content was 50 wt-%. 相似文献