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91.
Lithium sulfur cells were prepared by composing with sulfur cathode (PEO)6LiBF4 polymer electrolyte and lithium anode. (PEO)6LiBF4 polymer electrolyte was prepared under three different mixing conditions: stirred polymer electrolyte (SPE), ball-milled polymer electrolyte (BPE) and ball-milled polymer electrolyte with 10 wt%Al2O3 (BCPE). The effects of ball milling and additive were investigated by discharge test according to depth of discharge. The initial discharge capacity of lithium sulfur cell using BCPE was 1670 mAh g−1-sulfur, which was better than those of SPE and BPE, and approximately equal to the theoretical capacity. The cycle performance of Li/(PEO)6LiBF4/S cell was remarkably improved by the addition of Al2O3. 相似文献
92.
A novel synthesis method of thin-film composite Sn/C anodes for lithium batteries is reported. Thin layers of graphitic carbon decorated with uniformly distributed Sn nanoparticles were synthesized from a solid organic precursor Sn(IV) tert-butoxide by a one-step microwave plasma chemical vapor deposition (MPCVD). The thin-film Sn/C electrodes were electrochemically tested in lithium half cells and produced a reversible capacity of 423 and 297 mAh g−1 at C/25 and 5C discharge rates, respectively. A long-term cycling of the Sn/C nanocomposite anodes showed 40% capacity loss after 500 cycles at 1C rate. 相似文献
93.
能源问题是各国都非常关注的问题,节约能源非常重要。一些工业过程排放出大量的气体、蒸汽或热水中含有大量的余热。它们的排放,不仅造成环境的污染,而且浪费了能源。回收其中的余热显得尤为重要。溴化锂两级高温吸收式热泵是一种热升温机,它能利用70~100℃余热本身驱动,生产100~160℃的热水或蒸汽以供工业生产使用。文中介绍了两级溴化锂高温吸收式热泵的原理,对它的设计、性能等进行了分析,最后得出了结论。 相似文献
94.
This paper focuses on developing an efficient fuel storage and release method for hydrogen using lithium hydride hydrolysis for use in PEM fuel cells for low power sensor network modules over long durations. Lithium hydride has high hydrogen storage density and achieves up to 95–100% yield. It is shown to extract water vapor freely from the air to generate hydrogen and has a theoretical fuel specific energy of up to 4900 Wh/kg. A critical challenge is how to package lithium hydride to achieve reaction completion. Experiments here show that thick layers of lithium hydride nearly chokes the reaction due to buildup of lithium hydroxide impeding water transport and preventing reaction completion. A model has been developed that describes this lithium hydride hydrolysis behavior. The model accurately predicts the performance of an experimental system than ran for 1400 h and consists of a passive lithium hydride hydrogen generator and PEM fuel cells. These results offer important design guidelines to enable reaction completion and build long-duration lithium hydride hydrogen generators for low power applications. 相似文献
95.
NiO films were prepared by chemical bath deposition and electrodeposition method, respectively, using nickel foam as the substrate. The films were characterized by scanning electron microscopy (SEM) and the images showed that their morphologies were distinct. The NiO film prepared by chemical bath deposition was highly porous, while the film prepared by electrodeposition was dense, and both of their thickness was about 1 μm. As anode materials for lithium ion batteries, the porous NiO film prepared by chemical bath deposition exhibited higher coulombic efficiency and weaker polarization and its specific capacity after 50 cycles was 490 mAh g−1 at the discharge–charge current density of 0.5 A g−1, and 350 mAh g−1 at 1.5 A g−1, higher than the electrodeposited film (230 mAh g−1 at 0.5 A g−1, and 170 mAh g−1 at 1.5 A g−1). The better electrochemical performances of the film prepared by chemical bath deposition are attributed to its highly porous morphology, which shorted diffusion length of lithium ions, and relaxed the volume change caused by the reaction between NiO and Li+. 相似文献
96.
97.
以(NH4)2FeSO4、LiOH、Ti(SO4)2以及H3PO4为原料一步水热合成法制备不同温度下掺Ti4 -LiFePO4,然后进行碳包覆,XRD和SEM表明制备的样品为单一相的准球形纳米粉体;激光粒度分析表明在160℃温度下合成的粉体平均粒径最小,大约在140nm左右;恒电流充放电及电化学阻抗谱测试材料电化学性能表明在160℃温度下合成的掺Ti4 -LiFePO4/C材料充放电性能最好,0.1C倍率下首次放电容量为 160.97 mAh g-1,0.5C倍率下经过50次放电,容量保留率为95.28%,通过电化学阻抗计算出锂离子扩散系数为1.78?0-12cm2 s-1。 相似文献
98.
High-voltage LiNi0.5Mn1.5O4 spinels were synthesized by a low temperature solution combustion method at 400 °C, 600 °C and 800 °C for 3 h. The phase composition, structural disordering, micro-morphologies and electrochemical properties of the products were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and constant current charge–discharge test. XRD analysis indicated that single phase LiNi0.5Mn1.5O4 powders with disordered Fd-3m structures were obtained by the method at 400 °C, 600 °C and 800 °C. The crystallinity increased with increasing preparation temperatures. XRD and FTIR data indicated that the degree of structural disordering in the product prepared at 800 °C was the largest and in the product prepared at 600 °C was the least. SEM investigation demonstrated that the particle size and the crystal perfection of the products were increased with increasing temperatures. The particles of the product prepared at 600 °C with ~200 nm in size are well developed and homogeneously distributed. Charge/discharge curves and cycling performance tests at different current density indicated that the product prepared at 600 °C had the largest specific capacity and the best cycling performance, due to its high purity, high crystallinity, small particle size as well as moderate amount of Mn3+ ions. 相似文献
99.
Hu Cheng 《Electrochimica acta》2007,52(19):5789-5794
New gel polymer electrolytes containing 1-butyl-4-methylpyridinium bis(trifluoromethanesulfonyl)imide (BMPyTFSI) ionic liquid are prepared by solution casting method. Thermal and electrochemical properties have been determined for these gel polymer electrolytes. The addition of BMPyTFSI to the P(EO)20LiTFSI electrolyte results in an increase of the ionic conductivity, and at high BMPyTFSI concentration (BMPy+/Li+ = 1.0), the ionic conductivity reaches the value of 6.9 × 10−4 S/cm at 40 °C. The lithium ion transference numbers obtained from polarization measurements at 40 °C were found to decrease as the amount of BMPyTFSI increased. However, the lithium ionic conductivity increased with the content of BMPyTFSI. The electrochemical stability and interfacial stability for these gel polymer electrolytes were significantly improved due to the incorporation of BMPyTFSI. 相似文献
100.
Caixian Chang 《Electrochimica acta》2008,54(2):623-627
A novel hydrothermal synthesis was developed to prepare carbon-coated lithium vanadium phosphate (Li3V2(PO4)3) powders to be used as cathode material for Li-ion batteries. The structural, morphological and electrochemical properties were investigated by means of X-ray powder diffraction (XRD), thermogravimetry (TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and constant current charge-discharge cycling. This material exhibits high initial discharge capacity of 178, 173 and 172 mAh g−1 at 0.1, 0.2 and 0.5 C between 3.0 and 4.8 V, respectively. Moreover, it displays good fast rate performance, which discharge capacities of 136, 132 and 127 mAh g−1 can be delivered after 100 cycles between 3.0 and 4.8 V versus Li at a different rate of 1, 2 and 5 C, respectively. For comparison, the electrochemical properties of carbon-coated lithium vanadium phosphate prepared by traditional solid-state reaction (SSR) method are also studied. 相似文献