化学计量比对稀土-镁基合金结构和性能的影响

文章研究不同化学计或比的稀土-镁基贮氢合金Mn0.9Mg0.1(NiCoMnAl)5x(x=0.75,0.80,0.85,0.90)相的结构和电化学性能.研究表明,Mn0.9Mg0.1(NiCoMnAl)5x合金的主相均由LaNi5相和LaNi3相组成.但当x≤0.80时,合金中还有LaNi2.28相析出.合金电极的最大放电容量和高倍率性能都随着x值的增大先增加后减少,当x=0.80时,都达到最大值;合金电极在243 K时的放电容量随着x值的增加有显著提高;合金电极的循环稳定性随着x值增大而提高.     

元素替代在AB5型储氢合金中应用的研究进展

简要回顾了AB5型储氢合金的发展历程,综述了元素替代对AB5型储氢合金相结构与储氢性能的影响,总结了各种元素进行替代的研究进展。就目前的研究现状指出了元素替代在AB5型储氢合金应用中存在的问题以及今后的发展方向。     

Phase Structure and Electrochemical Properties of RE-Mg Based Composite Hydrogen Storage Alloys

Rareearth basedAB5 typealloy ,akindofhy drogenstoragealloyusedasnegativeelectrodemateri alsofthenickel/metalhydride (Ni/MH )secondarybattery ,haseasyinitialactivation ,longcyclelifeandlowcost ,butstillasmalldischargecapacity ,poorhigh ratedischargeability(HRD)andpoorpropertiesatlowtemperature[1,2 ] .Therefore ,howtoincreaseitsdischargecapacityandtoimproveotherelectrochemi calpropertiesismeaningfulbothintheoryandinpracticalapplication .Mg basedhydrogenstorageal loysareremarkablebecauseofitsr…     

锂离子二次电池LiMn2O4正极材料的研究

采用碳酸锂和电解二氧化锰为原料,通过高温合成法研究了不同合成条件对反应产物ＬｉＭｎ２Ｏ４结构,性能的影响,并对ＬｉＭｎ２Ｏ４中Ｌｉ离了非化学计量本比做了研究。结果表明,合成前研磨时间越长,所需合成的时间越短,合成最佳温度为７５０℃;随着锂离子量ｎ的增另,ＬｉｎＭｎ２Ｏ４的晶格常数减小,１≤ｎ≤１．１时合成产物结构最完整 、     

铁对K418合金组织性能的影响

着重研究了铁的质量分数从0.85%变化到3.32%时对K418镍基高温合金的组织及性能的影响。研究表明,铁含量的变化,没有改变K418合金中主要相的组成,且铁含量对高温拉伸强度的影响较小。当铁的质量分数超过1%后,使材料的延伸率发生了波动,但波动幅度较小,并且这也可能是因为熔炼过程不均匀造成的。     

Effect of lanthanum hydride on microstructures and hydrogen storage performances of 2LiNHe-MgH2 system

Hydrogen storage properties of 2LiNH2-MgH2 system were improved by adding lanthanum hydride （LaH3）, and the role of LaH3 in hydrogen sorption process of Li-Mg-N-H system was investigated. Temperature programmed sorption results showed that the addition of lanthanum hydride reduced the dehydriding/hydriding onset temperature of 2LiNH2-MgH2 system by at least 15 K. Moreover, A 0.053 wt.%/min average rate was determined for the hydrogen desorption of 2LiNH2-MgH2-0.05LaH3 composite, while it was only 0.035 wt.%/min for 2LiNH2-MgH2 system. Hydrogen absorption capacity increased from 1.62 wt.% to 2.12 wt.% within 200 min by adding LaH3 into 2LiNH2-MgH2 system at 383 K. In the dehydrogenation of 2LiNH2-MgH2-0.05LaH3 composite, LaH2 transferred to LaN phase, which reversed to LaH2 in the following hydrogen adsorption process. The reversible reaction of LaH2 ef- fectively promoted the hydrogen sorption of Li-Mg-N-H system. Moreover, the homogenous distribution of fine La hydride was fa- vorable to improving effect of lanthanum hydride.     

Microstructure and electrochemical characteristics of La0.7Ce0.3Ni3.75Mn0.35Al0.15Cu0.75-x（V0.81Fe0.19）x hydrogen storage alloys

Microstructure and electrochemical characteristics of La0.7Ce0.3Ni3.75Mn0.35Al0.15Cu0.75-x(V0.81Fe0.19)x hydrogen storage alloys were investigated. XRD indicated that La0.7Ce0.3Ni3.75Mn0.35Al0.15Cu0.75-x(V0.81Fe0.19)x alloys consisted of a single phase with CaCu5-type structure, and the lattice parameter a and cell volume V increased with increasing x value. The maximum discharge capacity first increased from 319.0 (x=0) to 324.0 mAh/g (x=0.05), and then decreased to 307.0 mAh/g (x=0.20). The high-rate dischargeability at the discharge current density of 1200 mA/g first increased from 52.1% (x=0) to 59.1% (x=0.15), and then decreased to 55.4% (x=0.20). The hydrogen diffusion in the bulky alloy was responsible for the high-rate dischargeability. Cycling stability first increased with increasing x from 0 to 0.10 and then decreased when x increased to 0.20, which was resulted from the synthesized effect of the improvement of the pulverization resistance and the decrease of corrosion resistance.     

电镀镍-钴合金对La-Mg-Ni基贮氢合金电化学性能的影响

为了改善La-Mg-Ni基贮氢合金的循环稳定性和综合电化学性能,研究了电镀镍-钴合金对La0.88Mg0.12Ni2.95Mn0.10Co0.55Al0.10贮氢合金粉末表面形貌和电极电化学性能的影响.FESEM表明,电镀处理后合金粉末表面沉积了球状的镍-钴合金颗粒.电化学性能测试表明,贮氢合金电极的放电容量、高倍率放电性能和循环稳定性均得到了显著改善.200周循环时合金电极的容量保持率从未处理合金电极的60%提高到镀覆镍-钴合金的80%,在放电电流密度1080mA/g下的高倍率放电性能提高了23%.线性极化曲线和电化学阻抗分析结果显示,包覆镍-钴合金后贮氢合金电极表面的电荷转移速率加快,电催化活性提高.     

(La_xNd_y)_(0.90)Mg_(0.10)Ni_(3.09)Mn_(0.12)Co_(0.60)Al_(0.13)贮氢合金自放电性能研究

为了提高La-Mg-Ni基贮氢合金的荷电保持率,本文研究了La/Nd比的变化对La-Mg-Ni基贮氢合金自放电性能的影响。随着Nd替代La量的增加,(LaxNdy)0.9Mg0.10Ni3.09Mn0.12Co0.60Al0.13(x/y=5,4,3,2,1)合金的荷电保持率先增大后减小,当x/y=4时,其荷电保持率达到最大值80.8%(318 K)。合金电极贮存后,FESEM-EDS和XRD分析表明,合金颗粒表面形成了Mg(OH)2和Nd(OH)3。P-C-T曲线和Tafel极化测试表明,随着Nd含量的增加,金属氢化物的稳定性呈现先增加后降低和腐蚀电流先减小后增大的规律。     

锂离子二交电池LiMn2O4正极材料的研究进展

锂离子二次电池锂锰氧化物正极材料因其价格低廉、性能优良而成为研究的热点。本文综述了近年来锂离子二次电池LiMn2O4正极材料的研究进展，并对该材料的结构、性能、合成方法以及存在的问题进行了重点阐述。LiMn2O4材料具有尖晶石结构，目前制备主要固相烧结和液相合成方法。通过加入过量的锂和引和杂原子及采用工艺可改善其循环性能。