Electrochemical Properties and Reaction Mechanism of Ti-V Multiphase Alloy at High Temperature

研究333 K时Ti0.17Zr0.08V0.35Cr0.1Ni0.3 合金的循环稳定性和高温倍率放电性能。333 K时,当放电电流密度为60 mA/g时,Ti0.17Zr0.08V0.35Cr0.1Ni0.3合金第1次放电容量为450 mAh/g。随着充放电循环的进行,放电容量迅速降低。当放电电流密度为2400 mA/g,截止电压为0.6 V时,Ti0.17Zr0.08V0.35Cr0.1Ni0.3合金的放电容量仍达到160 mAh/g。并详细探讨影响以上合金电化学性能的因素     

快速凝固Ti-Zr-Ni合金的电化学贮氢性能

采用铜辊快速凝固方法制备了Ti45Zr30Ni25和Ti50Zr25Ni25合金,并对合金作为镍-氢二次电池负极的动力学和电化学性能进行了研究.结果表明,Ti45Zr30Ni25为非晶相合金,Ti50Zr25Ni25合金由准晶相和非晶相组成.两合金电极的最大放电容量分别为129和132mAh/g.在240mA/g电流密度下,高倍率放电性能(HRD)分别为62.7%和63.3%.合金电极的交换电流密度分别为205.1和375.6mA/g,氢在合金中的扩散系数分别为5.4×10-11和5.8×10-11cm2·S-1.     

表面包覆对非晶态CeMg12合金电化学性能的影响

采用在CeMg12中添加镍粉球磨制备非晶态合金,并研究化学镀表面包覆Ni对其电化学性能的影响.结果表明,非晶态CeMg12具有很高的电化学放电容量,CeMg12+200%Ni(质量分数)球磨50 h后复合电极材料电化学容量达到1209.6 mAh/g,但是电化学循环稳定性较差,10次循环保持率为37.26%.通过化学镀镍进行表面包覆能明显提高合金的综合电化学性能.化学镀表面包覆Ni后,合金10个循环的保持率上升到69.67%:同时由于添加的Ni和包覆Ni的共同催化作用,合金高倍率性能也得到了相应的提高,HRD900由原来的54.2%提升到72.4%;但是由于化学镀过程中部分合金被氧化,使复合合金的最大放电容量略有下降.     

正交实验法研究电沉积Mg-Ni储氢合金的制备工艺

采用正交实验法研究了电沉积制各Mg-Ni型储氢合金的工艺条件.结果表明,各因素影响合金放电比容量的次序为:温度>氯化镁含量>次磷酸钠含量>电流密度>柠檬酸钠含量.得到的最佳电沉积工艺为:氯化镁含量180 g/L,柠檬酸钠含量60 g/L,次磷酸钠含量70 g/L,氯化镍含量30 g/L,硼酸含量30 g/L,电流密度100 mg/cm2,温度45℃,pH 3～4.此时制备的合金放电比容量达到250 mAh/g,有较为明显的充放电平台,首次充放电即达到最大容量;但随着循环次数的增加,放电容量下降较快.XRD分析表明,电沉积得到非晶态的Mg2Ni+Ni合金.     

Ag修饰对Mg基贮氢合金电化学性能的影响

针对熔体快淬法制备的非晶Mg65Ni27La8合金利用置换沉积的方法在非晶合金表面沉积金属Ag,以期改善合金电极的循环性能。修饰后的合金电极最大放电比容量虽然略低于修饰前的合金电极(590 mAh/g),但是都显示了较好循环稳定性。当Ag/Mg的摩尔比为1/5时,合金电极最大放电容量为551 mAh/g,且合金经过20个充放电循环后放电比容量保持率仍达69%;线性极化曲线显示其交换电流密度为353 mA/g;表面修饰后的合金颗粒之间的接触阻抗和合金表面的电荷传输阻抗均有不同程度的降低,分别由修饰前的0.91Ω和3.15Ω降低到0.33Ω和0.85Ω。     

CuxBy表面修饰对Mg50Ni50合金循环稳定性的影响

用机械合金化法合成了CuxBy合金和非晶态Mg50Ni50储氢合金.用同样的方法以CuxBy对非晶态Mg50Ni50合金进行表面修饰.探索了不同组成的CuxBy合金、同一组成不同比例(质量比,下同)的修饰对Mg50Ni50合金电极循环稳定性的影响.结果表明:不同组成的CuxBy合金对Mg50Ni50合金的表面修饰,都不同程度地提高了Mg50Ni50合金电极的循环稳定性.同一组成不同比例的修饰,对Mg50Ni50合金电极循环稳定性改性效果差异较大.当Mg50Ni50:Cu0..9B0.1=5:1时,初始放电容量为465 mAh·g-1,第50个循环放电容量为222 mAh·g-1.在保持高放电容量的前提下,有效地提高了非晶态Mg50Ni50合金电极的循环稳定性.     

Nd含量对快淬纳米晶和非晶（Mg24Ni10Cu2）100-xNdx（x=0~20）合金电化学性能的影响

采用快淬技术制备Mg2Ni型纳米晶和非晶（Mg24Ni10Cu2）100-xNdx （x=0,5,10,15,20）合金,研究快淬速度对合金相结构和电化学性能的影响。结果表明,快淬态无 Nd 合金为纳米晶结构,而添加 Nd 元素的快淬态合金为纳米晶和非晶结构,表明添加Nd元素可促进Mg2Ni型合金的非晶形成能力。当快淬速度从0增加至40 m/s时, x=0合金的放电容量从42.5增加至100.6 mA·h/g;x=10合金的放电容量从86.4增加至452.8 mA·h/g。与此同时, x=0合金的循环稳定性（S20）也由40.2%增加到41.1%,而x=10合金的S20值由53.2%增加到89.7%。     

Mg65Ni21Pr14非晶储氢合金电化学性能研究

采用铜模喷铸法制备了Mg65Ni21Pr14块体非晶合金,研究了该合金在充放电循环过程中组织变化及其对电化学性能的影响。XRD分析表明,非晶合金电极在第6次充放电循环后开始晶化,生成Mg2NiH4和Ni5Pr相。电化学测试表明,Mg65Ni21Pr14非晶合金电极经过3次循环即可活化,其最大放电容量达到429.4 mAh·g-1,经过100次循环后,容量保持率为87.63%。研究表明,非晶结构是实现合金高放电容量和循环稳定性的重要因素。     

ZrCr2合金对TiV1.1Mn0.9Ni0.5电极合金结构和电化学性能的影响

用两步熔炼法制备TiV1.1Mn0.9Ni0.5-ZrCr2复合电极合金。XRD、EDS、ICP及EIS等分析结果表明：复合合金具有与母体合金相同的双相结构,但是两相的特征参数以及复合合金电极的热力学特性均发生了一系列变化;组分合金在复合过程中产生明显的协同效应;复合合金电极的最大放电容量达到457.2 mAh/g;循环稳定性、荷电保持率和高倍率放电等动力学性能均得到显著改善;1000 mA/g放电电流密度时,复合合金电极的高倍率放电性能是由电极/电解质界面上的电化学反应和合金体内氢的扩散混合控制     

Co-B合金粉体的制备和电化学行为

通过NaBH_4还原CoSO_4溶液制备了Co_(0.68)B_(0.32),Co_(0.55)B_(0.45)和Co_(0.50)B_(0.50)一系列超细非晶态Co-B合金粉体.电化学测试表明,在300 mA/g的高电流密度下,3种合金电极的首次放电容量分别高达510.6,666.4和667.2 mA·h/g,经60次循环后,放电容量仍分别有331.6,379.5和390.5 mA·h/g.3种合金电极还表现出良好的高率放电性能,在1200 mA/g的放电电流密度下,放电容量分别为336.2,373.4和390.1 mA·h/g.较高的B含量有助于提高合金的电化学性能,这是因为B的氧化溶解能提高合金电极的实际电化学反应面积.     

Effect of commercial AB5 alloy addition on the electrochemical properties of Ml-Mg-Ni-based hydrogen storage alloys

A commercial AB5 hydrogen storage alloy was used as an additive to improve the electrochemical properties of Ml-Mg-Ni-based hydrogen storage alloys.The effect of AB5 alloy addition on the phase structure,charge/discharge characteristics,and electrochemical kinetics of Ml0.90Mg0.10Ni3.08Mn0.13Co0.63Al0.14 alloy was investigated.The maximum discharge capacity of Ml0.90Mg0.10Ni3.08Mn0.13Co0.63Al0.14 + 4 wt.% AB5 electrode reaches 406 mAh/g.The anodic polarization,cyclic voltammetry,and potential step discharge experiments show that the electrochemical kinetics of the electrode with additives was promoted,with the LaNi5 phase of AB5 alloy acting as electro-catalytic sites in the electrode alloy.The high-rate dischargeability of Ml0.90Mg0.10Ni3.08Mn0.13Co0.63Al0.14 + 4 wt.% AB5 alloy electrode at 1100 mA/g reaches 60.9%,which is 9.4% higher than that of Ml0.90Mg0.10Ni3.08Mn0.13Co0.63Al0.14 alloy electrode.The cycling stability of the electrode with 4 wt.% AB5 alloy has also been improved.     

Structure and Electrochemical Hydrogen Storage Properties of as-Milled Mg-Ce-Ni-Al-Based Alloys

At room temperature,crystalline Mg-based alloys,including Mg_2 Ni,MgNi,REMg_(12) and La_2 Mg_(17),have been proved with weak electrochemical hydrogen storage performances.For improving their electrochemical property,the Mg is partially substituted by Ce in Mg-Ni-based alloys and the surface modification treatment is performed by mechanical coating Ni.Mechanical milling is utilized to synthesize the amorphous and nanocrystalline Mg_(1-x)Ce_xNi_(0.9)Al_(0.1)(x=0,0.02,0.04,0.06,0.08)+50 wt%Ni hydrogen storage alloys.The effects made by Ce substitution and mechanical milling on the electrochemical hydrogen storage property and structure have been analyzed.It shows that the as-milled alloys electrochemically absorb and desorb hydrogen well at room temperature.The as-milled alloys,without any activation,can reach their maximal discharge capacities during first cycling.The maximal value of the 30-h-milled alloy depending on Ce content is 578.4 mAh/g,while that of the x=0.08 alloy always grows when prolonging milling duration.The maximal discharge capacity augments from337.4 to 521.2 mAh/g when milling duration grows from 5 to 30 h.The cycle stability grows with increasing Ce content and milling duration.Concretely,the S_(100) value augments from 55 to 82% for the alloy milled for 30 h with Ce content rising from 0 to 0.08 and from 66 to 82% when milling the x=0.08 alloy mechanically from 5 to 30 h.The alloys' electrochemical dynamics parameters were measured as well which have maximum values depending on Ce content and keep growing up with milling duration extending.     

Effect of La on the crystalline and electrochemical properties of Ti-Zr-Ni melt-spun alloys

Ti45Zr30Ni25 and Ti45Zr30Ni25La alloys were prepared by melt-spinning, and the phase structure and electrochemical performances of the melt-spun alloys were investigated. The results showed that the Ti45Zr30Ni25 alloy was composed of the quasicrystalline phase, amorphous phase and Laves phase. The Ti445Zr30Ni25La alloy contained quasicrystalline and amorphous phases. The maximum discharge capacity was 111 mAh/g for the Ti45Zr30Ni25 alloy electrode, and 124 mAh/g for the Ti45Zr30Ni25La alloy electrode. The Ti45Zr30Ni25La alloy electrode ex-hibited a better high-rate dischargeability and cycling stability than the Ti45Zr30Ni25 alloy electrode. The improvement of electrochemical properties was mainly ascribed to the increase in the amorphous phase due to the addition of La.     

Mg-Ni-Y-La非晶合金微观结构转变及电化学性能研究（英文）EI北大核心CSCD

采用铜模喷铸法制备了Mg60Ni23.6Y0.5La15.9块体非晶合金,并对其微观组织结构及电化学性能进行了研究。用XRD和SEM对Mg60Ni23.6Y0.5La15.9非晶合金在充放电过程中的微观结构进行分析。采用自动充放电测试系统对Mg60Ni23.6Y0.5La15.9非晶合金电化学性能进行了测试。结果表明:在吸氢放氢过程中合金的非晶态结构逐步转变为晶态,并且随着循环的进行逐渐形成了Mg2Ni H4、Mg2Ni和Mg(OH)2相。电化学性能测试结果表明:Mg60Ni23.6Y0.5La15.9非晶合金电极的放电容量变化过程可以分为4个阶段,其最大放电容量达到410.5m Ah/g,从而说明非晶结构有可能是非晶电极达到最大放电容量的关键因素。     

铸态及退火La1.9Ti0.1MgNi9合金的贮氢性能

采用磁悬浮感应熔炼及退火处理的方法,制备La1.9Ti0.1MgNi9合金。对合金样品的XRD、PCT和电化学测试表明,所有样品均由多相组成,LaNi5相为主相。当退火温度达到1173 K时,合金中LaMg2Ni9相消失,Ti2Ni相出现。退火处理能提高合金的晶化程度、降低吸放氢平台压。退火1073 K合金的有效吸氢量较高,在303 K时达到1.25% (质量分数)。La1.9Ti0.1MgNi9合金退火后,放电容量、循环稳定性以及高倍率放电性能得到极大改善,以1173 K退火合金电化学性能较好,其最大放电容量为377 mAh/g,1100 mA/g电流密度下的高倍率放电性能为0.839,经112次充放电循环后放电容量保持率为60%。     

Ti2Ni储氢合金的充放电特性及腐蚀行为

通过球磨晶态Ti2Ni合金制备非晶态Ti2Ni合金,采用X射线衍射、充放电测试、阳极极化曲线对不同结构的Ti2Ni储氢合金的充放电特性及腐蚀行为进行研究。结果表明:晶态Ti2Ni合金的首次电化学充氢容量可达480mAh/g,但首次放氢量仅为充氢量的一半,合金内形成了大量不可逆氢化物相。随后的充放电循环中几乎没有不可逆相的形成。非晶相能够有效抑制充氢过程中不可逆相的形成,且充放氢使非晶合金间隙发生了弹性变形。此外,非晶结构使合金在碱性电解液中的自腐蚀电位升高、腐蚀电流降低,显著提高了合金的耐蚀能力。     

Crystallographic and electrochemical characteristics of melt-spun Ti-Zr-Ni-Cu alloys

Ti44Zr32Ni22Cu2 and Ti41Zr29Ni28Cu2 alloys were prepared by the melt-spinning method. The phase structure was analyzed by X-ray diffraction,and the electrochemical performances of the melt-spun alloys were investigated. The results indicated that the Ti44Zr32Ni22Cu2 alloy was composed of the icosahedral quasicrystals and amorphous phases,and the Ti41Zr29Ni28Cu2 alloy comprised icosahedral quasicrystals,amorphous,and Laves phases. The maximum discharge capacity was 141 mAh/g for the Ti44Zr32Ni22Cu2 alloy and 181 mAh/g for the Ti41Zr29Ni28Cu2 alloy,respectively. The Ti41Zr29Ni28Cu2 alloy also showed a better high-rate dischargeability and cycling stability. The better electrochemical properties should be ascribed to the high content of Ni,which was beneficial to the electrochemical kinetic properties and made the alloy more resistant to oxidation,as well as to the Laves phase in the Ti41Zr29Ni28Cu2 alloy,which could work as the electro-catalyst and the micro-current collector.     

烧结法和熔炼法Ti_3Ni_2储氢合金的电化学性能

对比研究了烧结法和熔炼法制备的Ti3Ni2合金的储氢性能。结果显示,烧结合金具有多孔特性,有利于提高合金的电化学储氢性能。烧结合金的最大放电容量Cmax为305mAh/g,其值远高于熔炼合金的Cmax(242mAh/g)。另外,烧结合金在电化学动力学方面也优于熔炼合金,这主要是由于采用烧结法可以改善氢在Ti3Ni2合金中的扩散,从而使氢的扩散系数(D)从7.16×10-10cm2/s(熔炼合金)提高到3.2×10-9cm2/s(烧结合金)。     

机械球磨Mg2Ni0．95Sn0．05＋x％Ni非晶复合物的微结构和电化学性能

用机械球磨法合成了Mg2Ni0．95Sn0．05＋x％Ni（质量分数，x=25，50，75，100，125）非晶复合物，研究了其微结构和电化学性能。微结构分析表明，不添加Ni粉的Mg2Ni0．95Sn0．05合金经100h球磨后仍然难以形成非晶结构，加入镍粉有助于非晶结构的形成。电化学研究表明，铸态最大放电容量仅为16mAh／g，球磨100h后容量改善不明显；加入Ni粉球磨后，容量大幅上升，随着Ni添加量的增加，复合物最大放电容量先增后减，在x=75时达到最大值625.6mAh／g。把x=50时的复合物，延长球磨时间t，复合物最大放电容量提高，当t=200h时达到670mAh／g。     

Electrochemical Hydrogen Storage Characteristics of the as-Cast and Annealed La0.8-xPrxMg0.2Ni3.35Al0.1Si0.05 (x=0~0.4) Electrode Alloys

采用铸造及退火工艺制备了La0.8-xPrxMg0.2Ni3.35Al0.1Si0.05 (x=0, 0.1, 0.2, 0.3, 0.4)电极合金。系统研究了Pr的替代对合金的结构与电化学储氢性质的影响,结果表明除少量残余LaNi3相外,铸造及退火合金是由六方Ce2Ni7型(La, Mg)2Ni7相与六方CaCu5型LaNi5相构成的。Pr对La的置换对合金的电化学储氢性质产生明显影响,铸造及退火合金的放电容量和高倍率放电能力随Pr含量的增加先升后降。当Pr含量由0增加至0.4时,铸造及退火合金的100次充放电循环后容积保持率S100从64.96%和72.82%分别增加至77.94%和91.81%