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本文根据国内外有关储氢合金的表面处理方法研究,简要综述了几种表面处理技术的进展,同时对新型的表面修饰方法予以展望。 相似文献
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为提高La-Mg-Ni基储氢合金La_(0.73)Ce_(0.18)Mg_(0.09)Ni_(3.20)Al_(0.21)Mn_(0.10)Co_(0.60)的电化学性能,将制备的石墨烯添加到储氢合金中。经XRD分析可知,处理前后合金的相结构没有变化。添加质量分数为1%、2%、5%石墨烯的合金电极与未添加石墨烯电极相比,最大放电容量略有下降,但50次循环后的放电容量保持率从63%分别提高到75%、78%和73%。添加2%石墨烯电极和未添加石墨烯电极相比,900 m A/g放电电流密度下的高倍率放电容量保持率从79.8%增加到83.9%,交换电流密度I0从54 m A/g提高到281 m A/g,极限电流密度IL从512 m A/g提高到1 537 m A/g。加入石墨烯后,电极的抗腐蚀性能也明显增强。 相似文献
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研究了石墨烯含量对储氢合金物相组成和电化学性能的影响。结果表明,不同石墨烯含量储氢合金都主要由La3Ni13B2、LaNi5和(Fe,Ni)相组成,La3Ni13B2和(Fe,Ni)相晶胞体积会随着石墨烯含量增加而增大,LaNi5相晶胞体积会随着石墨烯含量增加而减小。当石墨烯质量分数从0%增加至6%时,储氢合金的最大放电容量先增加后减小,在石墨烯质量分数为4%时取得储氢合金放电容量最大值(288.5 mA·h/g),且当循环周期为100次时,石墨烯质量分数为4%和6%的储氢合金的放电容量仍然高于未添加石墨烯的储氢合金。相同温度下,添加石墨烯的储氢合金的放电容量都高于未添加石墨烯的储氢合金,且石墨烯质量分数为4%的储氢合金具有最大放电容量。随着石墨烯质量分数从0%增加至6%,储氢合金的电荷转移电阻先减小后增大、电流密度和扩散系数先增大后减小,在石墨烯质量分数为4%时取得电荷转移电阻最小值、电流密度和扩散系数最大值,适宜的石墨烯添加量为4%。 相似文献
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Cu替代Ni对La-Mg-Ni系储氢合金电化学性能的影响 总被引:1,自引:0,他引:1
用Cu替代LaMg2N i9系和MLMg2N i9(ML———富La混合稀土金属)系储氢合金中的部分N i,可以使合金的活化次数和放电容量衰减率减小。XRD及SEM分析表明,LaMg2N i7.8Cu1.2和La0.4Ce0.1Nd0.2Pr0.3Mg2N i6.9Cu2.1合金中MgN i2相、LaN i5相、LaCu3相和LaCu5相的存在,均有利于提高合金的活化性能,使循环放电容量增大。取代后综合电化学性能较好的合金分别是LaMg2N i7.8Cu1.2和La0.4Ce0.1Nd0.2Pr0.3Mg2N i6.9Cu2.1。 相似文献
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储氢合金是影响镍氢电池性能的主要因素,对储氢合金进行表面处理可以有效提高镍氢电池的性能。本文对储氢合金表面进行包覆镍硼合金处理,通过扫描电镜(SEM)及X射线衍射分析(XRD)对电极表面进行了表征,测定了包覆前后镍氢电池的大电流放电性能,以交流阻抗法和循环伏安法对电极进行了评价。结果表明,包覆镍硼合金后,电化学阻抗减小,电极的大电流放电性能有所提高,循环寿命增长,对储氢合金表面包覆镍硼合金可有效提高镍氢电池性能。 相似文献
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以La-Mg-Ni系A2B7型储氢合金为研究对象,系统分析了合金A、B侧元素含量对其电化学性能的影响。对La1-m-n-y Pr m Nd n Mg y(Ni1-z Co z)x合金的容量和衰减速率进行了讨论。结果表明,合金容量随B/A值的增大先增大后减小,当x=3.5时,合金的容量最大,衰减速率最小;最佳的合金配比为La0.5Pr0.2Nd0.1Mg0.2(Ni0.8Co0.2)3.5。XRD分析表明,La1-m-n-y Pr m Nd n Mg y(Ni1-z Co z)x的合金主相结构均为Ce2Ni7型La2Ni7相。 相似文献
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《分离科学与技术》2012,47(12-13):1275-1294
Abstract Dynamical problems facing hydrogen diffusion in metal hydrogen systems at low temperature are surveyed. A microscopic model is constructed based on the assumption that the functional units are clusters of Fermi or Bose particles, collectively referred to as spin clusters. Critical behavior of metal hydrogen systems provides a key approximation which makes our model soluble. The time-dependent autocorrelation functions are obtained by solving the Heisenberg equation of motion using a new mathematical technique called the recurrence relations. The dynamical solutions shed light on the reversed isotope effect in diffusion. The nature of interstitial spin clusters is examined and compared with atomic and nuclear spin clusters. The spin clusters show striking resemblance to the superfluid component in the two-fluid theory of liquid 4He. 相似文献
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《Drying Technology》2012,30(15):1771-1785
Advances in the study of the rate processes in spray drying have helped improve product quality. Single droplet drying (SDD) is an established method for monitoring the drying kinetics and morphological changes of an isolated droplet under a controlled drying environment, mimicking the droplet convective drying process in spray drying. To enhance particle quality requires understanding of both the particle formation process and knowledge of how different particle properties are affected by the drying conditions used. The latest development in the SDD technique enables evaluation of these aspects by incorporating a dissolution test in the drying experiment. The experiment is realized by attaching a solvent droplet to a dried/semi-dried single particle in situ and then video-recording the resultant morphological changes. Some of the particle (e.g., crystallinity) properties obtained under different drying conditions can be modelled using the measured droplet drying kinetics. This paper reviews the applications of SDD experiments in measuring the drying kinetics and monitoring the droplet morphological changes during drying. Some examples of extending the glass filament SDD technique to examine particle functionalities are discussed. SDD experiments are shown to be a powerful tool for particle engineering due to its ability to study both the external convective transport process of a single droplet and to understand the different particle functionalities of the resultant single dried particle. 相似文献
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Numerical simulation of multiphase flows in processing equipment in industry with two-fluid models and Eulerian-Lagrangian approaches requires the constitutive equations describing the interactions between the dispersed phase of high concentration and the continuous phase. The status of research on the forces on dispersed solid and fluid particles is reviewed in this article. As compared with the knowledge on drag of single solid particles, study on particle swarms and on other forces is not sufficient to meet the demand of reliable and efficient numerical simulation of multiphase flows. Thus, thorough study on the particle swarms becomes the key to accurate multi-scale simulation of multiphase flows. Besides, the development of efficient algorithm dealing with the non-uniformity on both equipment and mesoscopic scales is recognized as an important issue to be resolved. The research topics in the near future are suggested. 相似文献
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《化工机械》2015,(5)
采用分子动力学方法,研究了3种介质粒子(Cl-、OH-、H2O)与两种金属氧化膜界面Fe2O3(00-1)、Cr2O3(0 0-1)的交互作用能和它们在这些氧化膜表面的扩散过程。计算结果表明:Cl-与Fe2O3和Cr2O3的交互作用能分别为-8 875、-9 227kcal/mol,而OH-和H2O与Fe2O3的交互能仅仅为-225、-258kcal/mol。Cl-、OH-和H2O在Cr2O3中的扩散系数分别为6×10-5cm2/s、8×10-5cm2/s和3×10-6cm2/s。交互作用能说明:Cl-与金属氧化膜的作用性更强,OH-和H2O与金属氧化膜的作用性相对弱一点,因此交互作用能可以是评价粒子腐蚀性的重要依据之一;扩散系数也是评价粒子对金属腐蚀性的一个指标,但是评价单个粒子对金属的腐蚀性能时不仅取决于其自身的扩散系数,而且还应该与所在溶剂的分子在金属氧化物表面的扩散系数有关。 相似文献
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Electrochemical investigations were carried out on electrodes made from both bare and Pd-coated LaNi4.25Al0.75 particles. Experimental results showed that the Pd-coating significantly decreases the electrode resistance and increases the electrode discharge capacity. The electrochemical impedance spectroscopy technique was used to determine various resistive components in the electrodes and electrolyte by fitting an equivalent circuit to the experimental data. The results indicated that an electrode made from the Pd-coated alloy has much less ohmic resistance (particle-to-particle contact resistance and current collector to electrode pellet contact resistance) compared to the electrodes made from bare alloy. 相似文献
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The kinetics of liquid-phase hydrogenation of benzene in misch metal nickel-five (MlNi5) and benzene slurry system was studied by investigating the influences of the reaction temperature, pressure, alloy concentration and stirring speed on the mass transfer-reaction processes inside the slurry. The results show that the whole process is controlled by the reaction at the surface of the catalyst. The mass transfer resistance at gas-liquid interface and that from the bulk liquid phase to the surface of the catalyst particles are negligible. The apparent reaction rate is zero order for benzene concentration and first order for hydrogen concentration in the liquid phase. The kinetic model obtained fits the experimental data very well. The apparent activation energy of the hydrogen absorption reaction of MlNi5-C6H6 slurry system is 42.16 kJ.mol-1. 相似文献