Samples of LiNi0.95-xCoxAl0.05O2（x=0.10 and 0.15） and LiNiO2,synthesized by the solid-state reaction at 725?℃ for 24?h from LiOH·H2O,Ni2O3,Co2O3,and Al（OH）3 under an oxygen stream,were characterized by TG-DT...
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Samples of LiNi0.95-xCoxAl0.05O2（x=0.10 and 0.15） and LiNiO2,synthesized by the solid-state reaction at 725?℃ for 24?h from LiOH·H2O,Ni2O3,Co2O3,and Al（OH）3 under an oxygen stream,were characterized by TG-DTA,XRD,SEM,and electrochemical tests. Simultaneous doping of cobalt and aluminum at the Ni-site in LiNiO2 was tried to improve the cathode performance for lithium-ion batteries. The results showed that co-doping （especially,5% Al and 10% Co in atomic fraction） definitely had a large beneficial effect in increasing the capacity （186.2?mA·h/g of the first discharge capacity for LiNi 0.85 Co 0.1 0Al 0.05 O2） and cycling behavior (180.1?mA·h/g after 10 cycles for LiNi0.95-xCoxAl0.05O2) compared with 180.7?mA·h/g of the first discharge capacity and 157.7?mA·h/g of the tenth discharge capacity for LiNiO2,respectively. Differential capacity versus voltage curves showed that the co-doped LiNi0.95-xCoxAl0.05O2 had less intensity of the phase transitions than the pristine LiNiO2.
Al2O3/WC-10Co/ZrO2 cermets were prepared by a hot-pressing process by using WC-10Co nanocomposite powder, Y2O3 stabilized nanocrystalline ZrO2 powder and submicron Al2O3 powder. The influences of sintering temperature...
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Al2O3/WC-10Co/ZrO2 cermets were prepared by a hot-pressing process by using WC-10Co nanocomposite powder, Y2O3 stabilized nanocrystalline ZrO2 powder and submicron Al2O3 powder. The influences of sintering temperature on the microstructure, grain size and properties were investigated according to the density, fracture toughness, Rockwell A hardness (HRA), hysteresis loops and scanning electron microscopy (SEM) micrographs of fractured surfaces of the specimens. The results show that the composite powders (WC-10Co(50%)/Al2O3(40%)/ZrO2(10%)) after being high-energy ball-milled for 48 h was hot-pressing sintered at 1450°C, then submicron Al2O3/WC-10Co/ZrO2 cermets with an average grain size of less than 1 μm and better properties of 97.5% in relative density, 7.4468 MPa·m1/2 in fracture toughness, HRA 94.0 is achieved.
The physical performances of alumina cement-based composite fabricated by vibratory compaction by using alumina cement as gelling agent and graphite as conductive filler were studied in this paper. The change trends o...
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The physical performances of alumina cement-based composite fabricated by vibratory compaction by using alumina cement as gelling agent and graphite as conductive filler were studied in this paper. The change trends of volume resistivity, compressive strength and apparent density of these composite with graphite content were obtained. And the percolation theory was applied to explain the electrical mechanism of these composites. The experimental results showed that the volume resistivity of these composites varied in 106-102Ω·cm, which can be used as antistatic, electric engineering and electro thermal materials.
This paper introduced the preparation of zinc oxide whiskers with different morphology. The result of SEM showed that one was multi-needle whiskers, the other was hexagonal rods. The result of the XRD indicated that t...
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This paper introduced the preparation of zinc oxide whiskers with different morphology. The result of SEM showed that one was multi-needle whiskers, the other was hexagonal rods. The result of the XRD indicated that the production structure was wurtzite, which was mixed with hydrocarbon. The results of SEM indicated that the mixture had an important effect on the the morphology of the whiskers.
In this paper, fuel cell testing process was summarized. From the calibration of test station, parameters record and testing process, we analyzed the process and experiment condition which must be standardized in orde...
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In this paper, fuel cell testing process was summarized. From the calibration of test station, parameters record and testing process, we analyzed the process and experiment condition which must be standardized in order to obtain repeatable, reproducible and scaleable parameters of the performance and durability. Due to the process of fuel cell working is a complicated balanceable system including mass transfer, electrochemical reaction and thermo transfer etc, the fuel cell testing is consequentially a rigorous testing process. Every tache of it was restricted by the other, and every restricted factor will maybe influence the test results. So, a exhaustive testing protocol must be established.
Nafion/PTFE composite membranes based on different ePTFE were prepared in this work. Porous PTFE was perfectly impregnated by Nafion resin. The differences of mechanical properties such as tensile strengths and dimens...
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Nafion/PTFE composite membranes based on different ePTFE were prepared in this work. Porous PTFE was perfectly impregnated by Nafion resin. The differences of mechanical properties such as tensile strengths and dimensional changes were analyzed in this paper. From electrochemical and single cell tests, the optimum thickness of porous PTFE for the composite membrane is 15 μm. The performance of the composite membrane based on the 15 μm-thick porous PTFE was 0.664 V at 600 mA/cm2, which was higher than Nafion111 membrane at the same conditions.
The gas diffusion layer (GDL) durability of proton exchange membrane fuel cell (PEMFC) was reviewed. The testing methods and the characterization of the durability of GDL were summarized in this paper. The degradation...
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The gas diffusion layer (GDL) durability of proton exchange membrane fuel cell (PEMFC) was reviewed. The testing methods and the characterization of the durability of GDL were summarized in this paper. The degradation mechanisms of GDL were analyzed through discussion. The research trends of the GDL were proposed as well.
This paper modeled a single cell with active area of nearly 50 cm2 by the CFD software of Fluent and discussed the influence of cooling water on the temperature distribution of membrane. The results show that most of ...
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This paper modeled a single cell with active area of nearly 50 cm2 by the CFD software of Fluent and discussed the influence of cooling water on the temperature distribution of membrane. The results show that most of the cooling water's temperature is low, the effect of heat exchange is bad;At the high current density, cooling water with the same flow direction of reactant gas has better effect on improving temperature distribution in the fuel cell. Increasing overall flow velocity and depressing the inlet temperature of cooling water has little effect on improving temperature distribution.
High alumina cement/graphite conductive composites were prepared by mold pressing at room temperature. Electrical conductivity was measured and the composite morphology was investigated by scanning electron microscope...
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High alumina cement/graphite conductive composites were prepared by mold pressing at room temperature. Electrical conductivity was measured and the composite morphology was investigated by scanning electron microscope (SEM). The heat stability and water content of conductive composites were also studied under proton exchange membrane fuel cell (PEMFC) operating temperature. The test results show that the percolation phenomenon is exist in the composite bipolar plate, the threshold value is 8%-10%;moreover, the composite bipolar plate has excellent heat stability and self- humidification.
Metal-N-H is considered as one of the most-potential hydrogen storage materials as on-board applications for its high gravimetric hydrogen content at relatively gentle condition. The research development of conversion...
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Metal-N-H is considered as one of the most-potential hydrogen storage materials as on-board applications for its high gravimetric hydrogen content at relatively gentle condition. The research development of conversion from Li-N-H to Mg-N-H is presented, two types of possible reaction mechanisms are discussed and three amide-synthesizing methods are introduced. The unsolved problems of development and application of the Metal-N-H system are also generalized.
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