Ti-Mn基Laves相贮氢合金的研究

采用P-C-T曲线测试和XRD分析研究了Ti/Zr比变化对Ti-Mn基Laves相贮氢合金贮氢性能的影响.实验结果表明,随Ti/Zr比降低,合金放氢压力降低,贮氢量略微增加,平台坡度变陡.同时还研究了Mn/Cr比变化对Ti-Mn基Laves相贮氢合金晶体结构、活化性能以及贮氢性能的影响.着重探讨了Mn/Cr比变化时影响合金平衡压力的2个因素.对(Ti0.85Zr0.15)Mn1.4Cr0.2V0.32Fe0.08(x=-0.025,0,0.05,0.1)系列合金,根据其P-C-T测试和XRD分析结果,讨论了x的变化对合金贮氢量、平衡压力、α区宽度的影响.     

ZrTi-V-Mn-Ni系贮氢合金的相结构与电化学性能研究*

优化合金组成,设计六种锆基AB2型贮氢合金材料。XRD分析表明,当0≤x≤0.5时,Zr1-xTix(NiCoMnV)2.1贮氢合金的主相都是Laves C15,但随Ti含量的增加,Laves C14相含量增多;当用V-Fe(85.6%)合金代替Zr0.6Ti0.4(NiCoMn-VFeCr)1.7中的V时,贮氢合金中Laves C14相的含量几乎可与Laves C15相当。电化学测试表明：Zr0.9Ti0.1(NiCoMnV)2.1贮氢电极的放电容量可达340mAh/g左右,但是随着Ti含量的逐渐增加,合金电极的放电容量降低很快。以适量的（V－Fe)合金取代Zr0.6Ti0.4(NiCoMnVFeCr)1.7合金中的V和Fe,发现合金电极的第一次放电容量就能达到200mAh/g左右,并且其容量稍高于含纯V的合金电极,容量可达315mAh/g左右。     

贮氢材料钒基固溶体合金的研究进展

钒基固溶体合金是一类重要的贮氢材料.概述了金属钒的氢化特性,讨论了钒基固溶体合金有效贮氢量低的原因;综述了合金组元及非金属杂质元素对钒基固溶体合金性能的影响,在吸氢主要元素钒基中添加其它元素(Ti、Ni、Cr、Mn、Fe、Hf、Zr、Nb、Co、Al、Si等)有利于提高合金的贮氢性能.     

机械合金化制备Mg76-xTi12Ni12Mnx（x=2,4,6,8）合金及其贮氢性能研究

利用机械合金化法制备了Mg76-xTi12Ni12Mnx(x=2,4,6,8)合金,并研究了Mn添加量对合金贮氢性能的影响。结果表明,在Mg76-xTi12Ni12Mnx(x=2,4,6,8)合金中合金相主要由Mg2Ni和Ti2Ni相组成,合金最大贮氢量分别为3.47%、3.32%、3.60%和3.11%(质量分数,下同),合金氢化物的分解热依次为-79.2kJ/mol、-78.0kJ/mol、-73.7kJ/mol和-73.6kJ/mol,添加Mn可降低合金氢化物的稳定性,改善其热力学性能,非晶化不利于提高合金的贮氢性能。     

Zr-Cr-Ni系AB_2型Laves相贮氢合金及其电化学性能的研究

首次系统地研究了Zr-Cr-Ni系Laves相贮氢合金晶体特性及其电极特性。首先从Zr(Cr_xNi_(1-x))_2系三元贮氢合金入手,探讨了合金成分、晶体特性与合金电极性能之间的关系。在x=0.15～0.65范围内,三元贮氢合金主相均属于Laves相结构,在x=0.45～0.50范围内,其主相晶体结构类型发生从C15型向C14型转化,且晶格常数随Cr量增加而增大,并且在x=0.35～0.50范围内,合金电极具有较好的电化学性能。用3d过渡元素Mn、V、Fe、Co、Ti等对三元合金中A或B组元进行部分代替,以调整所形成的氢化物的稳定性,并使之具备合适的晶体结构类型及相组成含量分布。提出Zr系合金电极的成分设计方向及一般规律性。表面清洁、高比表面积和高缺陷密度是促使Zr系贮氢合金气态活化性能得到改善的根本原因。过渡族元素多元化替代可以明显地改善Zr系贮氢电极的活化性能,其中以La、Ti等大原子半径尺寸元素的作用较为突出。采用HF稀溶液处理及气态吸放氢循环致碎的制粉方式和高温下放电均有利于加快电极的活化速度,同时指出合金颗粒度对此性能影响甚微。Zr-Cr-Ni系电极具有优良的抗氧化腐蚀能力,从而具有好的循环寿命性能。同时推导出贮氢电极在恒电流阳极极化作用下的阳极过电位表达式。在开口式电解池中,贮氢电极的容量保持率CR值,除了与环境     

Zr1-xTix(Ni0.6Mn0.3V 0.1Cr0.05)2(x=0～0.5)Laves相储氢合金的电化学性能

本文研究Zr1-xTix(Ni0.6 Mn0.3V0.1Cr0.05)2(x=0,0.1,0.2,0.3,0.4,0.5)系Lav es相储氢电极合金的气态P-C-T性能、晶体结构及电化学性能.XRD分析表明,Ti合金化使 Zr基储氢合金主相从C15相转变为C14相.当x>0.2时,第二相Zr7Ni10相消失, 并出现TiNi相.Ti合金化使Zr基储氢合金中C15相和C14相的晶格常数线性递减.气态P-C-T 测试表明,Ti合金化从x=0增加至x=0.5时合金的吸放氢平台压力升高约10倍,但降低了储氢合金的最大储氢容量.电化学测试表明,Ti合金化有利于改善Zr基储氢合金的活化性能, 这与Ti在KOH溶液中易于溶解有关,但过高的Ti含量降低了合金电极的循环稳定性.Zr1 -xTix(Ni0.6Mn0.3V0.1Cr0.05)2合金的电化学容量和高倍率放电性能均随合金中Ti含量的增加先上升后下降,这与合金的相结构组成有很大关系 .     

Zr_(1-x)T_xMn_(0.6)Ni_(1.4)(T=Ti,V)合金的晶体结构和贮氢特性

本文研究了Zr_(1-x)T_xMn_(0.6)Ni_(1.4)(T=Ti,V;x=0,0.1,0.2,0.4,0.6)合金的晶体结构和贮氢特性。这种合金的晶体结构属于Laves相的六方结构,空间群为P6_3/mmc。用Ti和V原子替代部分Zr原子后,六方结构的晶格常数变小。六方结构晶格常数的变小致使合金的氢平衡分解压随着Ti和V原子含量的增加而升高。     

Ti、La对贮氢合金ZrMn0.7 V0.2 Co0.1 Ni1.2相结构和电化学性能的影响

研究了贮氢电极合金Zr1-xTixMin0.7V0.2Co0.1Ni1.2的相结构和电化学性能。结果表明，随着掺Ti量的增加，该合金主相中C15型Laves相含量逐渐减少而C14型Laves相含量逐渐增加，同时非Laves相Zr7M10和TiNi相全部消失，说明元素Ti掺杂量的增加抑制了第二相的产生。当含Ti量x=0．2时，该合金具有最大放电容量Cmax为354mAh／g，在放电电流为300mAh／g条件下，高倍率放电性能比母体合金提高了15％。而对于合金Zr0.75Ti0.2La0.05Mn0.7V0.2Co0.1Ni1.2，其活化性能被大大提高，只需4次就能达到最大放电容量372mAh／g，而且经过30次循环仍能保持最大放电容量的93％。     

Ml_βMm_(1-β)(NiCoMnTi)_5贮氢合金的电化学性能和Rietveld分析 (1)电化学性能

在 AB5型混合稀土 -镍系贮氢多元合金的研究中 ,为设计高性能的 AB5型贮氢电极合金 ,人们对其 B侧多元合金化和 A侧稀土组元分别进行了系统地研究。在 B侧金属多元合金化研究工作比较成熟的基础上 ,进行贮氢合金中稀土组元的综合优化研究 ,是挖掘提高 AB5型合金性能另一重要途径。 La、Ce、Nd和 Pr含量及比例对 RE( Ni Co Mn Ti) 5合金电化学性能有很大影响 ,但添加纯 La,Ce和 Nd来调整其稀土成分 ,价格昂贵。本工作通过对 RE( Ni Co Mn Ti) 5合金中稀土组元 ( RE=MlβMm1-β)进行组合优化研究 ,主要还是依赖于市售的混合稀土金属原材料 ,利用不同种类的混合稀土中 L a、Ce、Nd和 Pr组元相应变化 ,来调整其稀土成分。结果表明 ,Ml:Mm比例对其电化学有显著影响。Ml0 .85Mm0 .15( Ni Co Mn Ti) 5对应合金具有最高放电容量为 2 80 m A h/ g和较好的循环寿命 ,并采用Rietveld精细结构法分析 La、Ce、Nd和 Pr作用机理。     

Ti0.4Zr0.1V1.1Mn0.5Ni0.4Crx（x=0,0.1,0.2,0.3）储氢合金的微观结构和电化学性能

采用XRD、SEM-EDS等方法对Ti0.4Zr0.1V1.1Mn0.5Ni0.4Crx(x=0,0.1,0.2,0.3)储氢合金的微观结构及电化学性能进行了表征。XRD分析结果表明Ti0.4Zr0.1V1.1Mn0.5Ni0.4Crx(x=0,0.1,0.2,0.3)储氢合金由BCC结构的V基固溶体主相和少量的C14Laves第二相组成。SEM-EDS分析结果表明,V基固溶体主相为树枝晶结构,C14Laves相呈网格状沿着主相晶界析出。电化学测试结果表明,Ti0.4Zr0.1V1.1Mn0.5Ni0.4Crx(x=0,0.1,0.2,0.3)氢化物电极在303K下,随Cr含量的增加,最大放电容量分别为574.6mAh/g、418.8mAh/g、368.8mAh/g和322.9mAh/g。当x=0.3时,合金电极在333K下的最大放电容量达到了824.1mAh/g。Cr的添加显著提高了合金电极的高倍率放电性能和循环寿命,40次充放电循环后Ti0.4Zr0.1V1.1Mn0.5Ni0.4Cr0.3合金电极的容量保持率为62.3%。     

Electronic structures of hydrogen storage compound, TiFe

The electronic structures of TiFe hydrogen storage compound containing a variety of alloying elements, M, are investigated by the DV-X cluster method in order to understand alloying effects on the hydrogen absorption and desorption characteristics of this compound. It is found that hydrogen atoms make a strong chemical bond with Fe atoms rather than Ti atoms in pure TiFe, despite the larger affinity of Ti atoms for hydrogen than Fe atoms in the binary metal–hydrogen system. It is also shown that the nature of the chemical bond between the constituent atoms determines the stability of TiFe hydrides. For example, the ratio of the Fe(M)–Ti bond order to the Ti–Ti bond order correlates well with the experimental data of the equilibrium plateau pressure of hydrogen.     

Design of hydrogen storage alloys with the aid of molecular orbital method

The electronic structures of hydrogen storage alloys are calculated by the DV-Xα molecular orbital method. The results revealed that hydrogen interacts more strongly with hydride-non-forming elements, B, (e.g. Ni, Mn, Fe) than hydride-forming elements, A, (e.g. La, Zr, Ti, Mg) in every hydrogen storage alloy, despite there being a larger affinity of A elements for hydrogen than B elements in the binary metal-hydrogen system. The presence of such a metal-hydrogen interaction is a characteristic of hydrogen storage alloys. Furthermore, the A/B compositional ratio of hydrogen storage alloys can be understood in terms of a simple parameter, 2Bo(A-B)/[Bo(A-A)+Bo(B-B)], where the Bo(A-B), Bo(A-A) and Bo(B-B) are the bond orders between atoms given in the parentheses.     

镁基储氢复合材料的研究进展

综述了镁基储氢复合材料开发和研究的最新进展，重点介绍了稀土／镁基储氢复合材料和镍／镁基储氢复合材料的主要种类、吸放氢性能和相关的制备工艺，简要分析了钛、铁、钒、锆／镁基储氢材料的研究现状和存在的问题，讨论了镁基储氢复合材料在储氢电极材料方面的应用前景。     

AB5-type Hydrogen Storage Alloy Modified with Ti/Zr Used as Anodic Materials in Borohydride Fuel Cell

1. IntroductionFuel cells are attractive alternative energy conversiondevices due to their higher efficiency and low pollution.Some fuel cells such as the proton exchange membranefuel cell (PEMFC), the alkaline fuel cell (AFC), and thephosphoric acid fuel cell (PAFC) require gaseous hydro-gen as the fuel. Establishing an available hydrogen stor-age system for these fuel cells is a key to satisfy the re-quirement of practical application. Though researchersin the world developed all kinds …     

Surface modification of AB(2) and AB(5) hydrogen storage alloy electrodes by the hot-charging treatment

The effect of the hot-charging treatment on the performance ofAB2 and AB5 hydrogen storage alloy electrodes was investigated. The result showed that the treatment can markedly improve the voltage plateau ratio (VPR), the high rate discharge ability (HRDA), the diffusion coefficient of hydrogen DH and the discharge capacity of the AB2 hydrogen storage alloy electrode. The SEM analysis showed that the hot-charging treatment brings about a Ni-rich surface due to the dissolution of Zr oxides. It is also very helpful for the improvement of the kinetic properties of AB2 hydrogen storage alloy electrode because the microcracking o.f the surface results in fresh surface. This can be the basic modification treatment for NiMH battery used in electric vehicles (EVs) in the future. But for AB5 type alloys, the treatment has the disadvantage of impairing the comprehensive electrochemical properties, because the surface of the alloy may be corroded during the treatment. The mechanism of the surface modification of the electrode is also proposed.     

Investigation of Zr-incorporated mesoporous titania materials via nonsurfactant templated sol-gel route: Synthesis, characterization and stability

The synthesis of Zr-incorporated mesoporous titania materials was achieved by a HCl-catalyzed nonsurfactant templated sol-gel process, followed by solvent extraction to remove the urea template. The materials were characterized by FT-IR, X-ray energy dispersive spectroscopy (XEDS), nitrogen adsorption-desorption measurement (BET), powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). Zirconia has been successfully incorporated into the skeleton of titania and the observed Zr/Ti compositions are close to the designed Zr/Ti molar ratios in the feeds. The content of zirconia has significant effects on the mesoporosity and the pore parameters as well as the thermal and hydrothermal stabilities of the materials. Anatase crystal structures were formed in the materials with low Zr/Ti molar ratios. As the Zr/Ti ratio is increased, the content of anatase structures decreases and the material becomes essentially amorphous at the Zr/Ti ratio of 1/1. The materials have narrowly distributed average pore diameters in the range of 2.5–5.1 nm and disordered pore or channel structures. The incorporation of Zr increases the thermal stability but decreases the hydrothermal stability of the materials.     

高温退火对V30Ti33Cr27Fe10贮氢合金性能与结构的影响

研究了高温退火处理对V30Ti33Cr27Fe10贮氢合金性能与结构的影响。结果表明高温退火使放氢平台变平，平台压降低，减小了合金吸放氢后的体胀，改变了合金晶粒的形态，改善了合金基体的组织均匀性。随保温时间延长，合金晶粒长大，晶胞体积减小，吸放氢量降低，BCC主相中析出越来越多的富Ti相，富Ti相中Fe含量随保温时间延长而减少。1523K保温30min的合金具有最大的室温吸放氢量，分别为3．679，5和2．14%（质量分数）；保温3h的合金具有最好的室温吸氢动力学性能，5min内就能达到其饱和吸氢量的80％。     

Structural, microchemistry, and hydrogenation properties of TiMn0.4Fe0.2V0.4, TiMn0.1Fe0.2V0.7 and Ti0.4Zr0.6Mn0.4Fe0.2V0.4 metal hydrides

In this work, TiFe-based alloys have been developed according to the stoichiometry Ti1-xAx Fe1-yBy (A [triple bond] Zr; B [triple bond] Mn, V). The hydrogen solubility properties have been investigated to develop dynamic hydrides of Ti-based alloys for hydrogen storage applications. The hydrogenation behavior of these alloys has been studied, and their hydrogen storage capacities and kinetics have been evaluated. Several activation modes, including activation at high temperatures under hydrogen pressure, have been attempted for the as-milled powders. In order to clarify the structural/microstructural characteristics, and chemical composition before and after hydrogenation, X-Ray Diffraction (XRD), EDAX-Mapping Analysis and Scanning Electron Microscopy (SEM), have been carried out for the samples. Modeling of the isotherms has been performed by using MATLAB programming. The maximum gravimetric density of 4.3 wt%, has been obtained on the sample with the BCC main phase. The calculated enthalpy of reaction (deltaH) is found to be about 4 kJ/mol.