Electrochemical performance of alloys Ho5Fe3CO12 and Ho33.3Co66.7

Alloys with composition Ho5Fe3Co12 and Ho33.3Co66.7 were prepared and examined by X-ray diffractometer and automatic battery testing instrument. The electrochemical properties of these alloys such as discharge capacity, cycling performance and high rate dischargeability were investigated by battery testing instruments in alkaline electrolyte. A comparison of the electrochemical performance of the Ho5Fe3Co12 and Ho33.3Co66.7 alloys revealed that alloy Ho5Fe3Co12 possessed a better electrochemical performance...     

气雾化低钴贮氢AB_5型合金的电化学性能和Rietveld分析

用快速凝固气体雾化法制备了低钴系列贮氢合金MlNi4 .3 -xCoxMn0 .4 Al0 .3 (x =0 75 ,0 45 ,0 2 9,0 1,Ml为富镧混合稀土 )并测试其电化学性能。气雾化法可显著提高贮氢合金电极的充 放电循环稳定性 ,x =0 45时合金的循环寿命与商用铸态合金的寿命相当。最大放电容量随着Co含量的增加 ,先增大后减小 ,在x=0 2 9时出现极大值 (30 4 4mAh/g)。结合循环寿命和最大放电容量两个性能指标 ,x =0 45时的合金具有良好的综合电化学性能。采用Rietveld法 (多晶衍射图形拟合法 )对其精细结构进行分析 ,合金仍保持母合金LaNi5的CaCu5型六方晶系结构 ,合金的晶胞体积对其循环寿命和最大放电容量起决定作用     

Effect of cobalt content on electrochemical performance of La-Mg-Ni system （Ce2Ni7-type） electrode alloys

In order to improve the cyclic stability of La-Mg-Ni system （Ce2Ni7-type） alloy electrode, small amount of Co was added in La0.75Mg0.25Ni3.5 alloy. The effect of Co on electrochemical performance and microstructure of the alloys were investigated in detail. XRD results showed that the alloys had multiphase structure composed of （La, Mg）2Ni7, LaNi5 and small amount of LaNi2 phases. The discharge capacity of the alloys first increased and then decreased with increasing Co content. At a discharge current density of 900 mA/g, the HRD of the alloy electrodes increased from 81.3% （x=0） to 89.2 % （x=0.2）, and then reduced to 87.8 % （x=0.6）. After 60 charge/discharge cycles, the capacity retention rate of the alloys enhanced from 52.67% to 61.32%, and the capacity decay rate of the alloys decreased from 2.60 to 2.05 mAh/g per cycle with increasing Co content. The obtained results by XPS and XRD showed that the fundamental reasons for the capacity decay of the La-Mg-Ni system （Ce2Ni7-type） alloy electrodes were corrosion and oxidation as well as passivation of Mg and Lain alkaline solution.     

Effects of annealing on microstructures and electrochemical properties of La0.8Mg0.2Ni2.4Mn0.10Co0.55Al0.10 alloy

The La0.8Mg0.2Ni2.4Mn0.10Co0.55Al0.10 alloy was prepared by induction melting. The structural and morphological characterizations were performed by means of X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical measurements were performed using LAND and CHI 660b electrochemical workstation. The main phases of the alloy were LaNi5 and (La,Mg)Ni3. After annealing, the maximum discharge capacity, cycle stability and high rate dischargeability (HRD) were improved obviously. The maximum discharge capacity reached 373.80 mAh/g (T=1173 K), the C100/Cmax(%) was 72.63% (T=1173 K), and the value of HRD reached 51.8% at a discharge current density of 1150 mA/g (T=1173 K). The cyclic voltammetry (CV) and potentiodynamic polarization were also studied.     

Study on structure and electrochemical properties of the （LaGdMg）Ni3.35-xCoxAl0.15（x=0-2.0） hydrogen storage alloys

Hydrogen storage alloys(LaGdMg)Ni3.35-xCoxAl0.15(x=0,0.1,0.3,0.5,1.0,1.5,2.0) were prepared by induction melting followed by annealing treatment in argon atmosphere.The effects of partly replacing Ni by Co element in(LaGdMg)Ni3.35Al0.15 on the phase structure and electrochemical properties of(LaGdMg)Ni3.35-xCoxAl0.15 alloys were investigated.Structure analysis showed that the alloys consisted of Ce2Ni7-type(Gd2Co7-type),CaCu5-type,Pr5Co19-type,PuNi3-type phase structure.The addition of Co element obviously reduced the contents of CaCu5-type phase and increased the contents of Ce2Ni7-type phase.However,Pr5Co19-type and CaCu5-type phase obviously increased with the high content of Co.Rietveld analysis showed that the c-axis lattice parameters and cell volumes of the component phases increased with increasing Co content.The electrochemical measurements showed that as the Co content increased,the maximum discharge capacity and the cyclic stability of the annealed alloys both first increased then decreased.The(LaGdMg)Ni3.05Co0.3Al0.15 alloy electrode exhibited the maximum discharge capacity(392.92 mAh/g),and the(LaGdMg)Ni1.85Co1.0Al0.15 alloy electrode showed the best cyclic stability(S100=96.1%).     

Application of Nanocrystalline LaNi5-type Hydrogen Absorbing Alloys in Ni-MHx Batteries

Duringlastyears ,interestinthestudyofnanos tructuredmaterialshasbeenincreasing .Thisisduetorecentadvancesinmaterials′synthesesandcharacteri zationtechniquesandtherealizationthatthesemateri alsexhibitmanyinterestingandunexpectedphysicalaswellaschemicalpropertieswithanumberofpoten tialtechnologicalapplications .Forexample ,hydrogenstoragenanomaterialsarethekeytothefutureofthestorageandbatteries/cellsindustries[1,2 ] .TheTiFe ,ZrV2 andLaNi5phasesarefamiliarmaterialswhichabsorblargequantitiesof…     

碳酸盐共沉淀法合成Li1＋xNi0.6Co0.2Mn0.2O2Fx正极材料及其电化学性能

采用碳酸盐共沉淀法合成Li1＋xNi0.6Co0.2Mn0.2O2Fx正极材料,研究了不同含量的Li、F复合掺杂对LiNi0.6Co0.2Mn0.2O2样品的晶型结构、形貌以及电化学性能的影响.研究结果表明：Li、F复合掺杂未改变LiNi0.6Co0.2Mn0.2O2样品的层状结构;掺杂后的样品颗粒细化;电化学循环性能和电极过程的可逆性明显得到提高.掺杂量x=0.06时,Li1＋xNi0.6Co0.2Mn0.2O2Fx样品的首次充放电容量分别为168,160 mA·h/g,循环50次后容量为153 mA·h/g.     

Effects of Strip Casting and Annealing on Electrochemical Properties of LPCNi3.55Co0.75Mn0.4Al0.3 Hydrogen Storage Alloys

The effect of thickness (1～10 mm) of the ingots on the electrochemical properties of as-cast and annealed strip cast LPCNi3.55Co0.75Mn0.4Al0.3 hydrogen storage alloys was investigated. It is found that the 0.2 C discharge capacity of as-cast LPCNi3.55Co0.75Mn0.4Al0.3 alloy increases with the increase of the thickness of the ingots. As-cast alloy with the thickness of 10 nun shows better activation property, higher 1C discharge capacity and better cyclic stability than others.It is mainly contributed to its larger unit cell volume and less internal stress. Annealed LPCNi3.55Co0.75Mn0.4Al0.3 alloywith the thickness of 3 mm shows much better comprehensive electrochemical properties than as-cast one; The cyclic stability of the alloy with the thickness of 6 mm and the activation properties of the alloys with the thickness of 3～6 mm are improved after annealing. It is mainly owing to the great release of intemal stress and the decrease fo the segregation of Mn in the alloys.     

LiNi0.6Co0.1Mn0.3O2正极材料的合成与性能

采用共沉淀-高温固相法制备LiNi0.6Co0.1Mn0.3O2锂离子正极材料,并使用X 射线衍射仪（XRD）和扫描电镜（SEM）技术分别表征其结构和形貌.然后将所得LiNi0.6Co0.1Mn0.3O2正极材料组装成扣式电池,并表征其电化学性能,探讨烧结温度和锂配量对其电化学性能的影响.结果表明：所得LiNi0.6Co0.1Mn0.3O2正极材料的放电比容量随烧结温度的升高而增大,且在900℃时表现出最佳的电化学性能.室温下,1C倍率下,锂配量(n(Li)/n(Ni+ Co+ Mn)=1.09)时,正极材料的首次放电容量为143.7 mAh/g,50次循环后,正极材料的放电比容量仍有141.3 mAh/g,容量保持率为98.3%.     

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.     

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…     

Structure and electrochemical hydrogen storage characteristics of Ce-Mg-Ni-based alloys synthesized by mechanical milling

The substituting Mg with Ni and milling as-cast alloy with Ni were adopted to obtain nanocrystalline/amorphous CeMgnNi+x wt.%Ni(x=100,200) alloys and promote the electrochemical hydrogen storage performances of CeMg_(12)-type alloys.Analyzing the structural features of the alloys provided a mechanism for ameliorating the electrochemical hydrogen storage properties.The electrochemical tests demonstrated that all the alloys just needed one cycle to be activated.Rising Ni proportion had an obvious role on charge-discharge reaction.The discharge capacities of the as-milled(60 h) alloys increased sharply from 182.0 mAh/gfor x=100 alloy to 1010.2 mAh/gfor x=200 alloy at current density of 60 mAh/g.Furthermore,milling time largely determined the performances of electrochemical reaction.The discharge capacity continued to grow along with prolonging milling time,while the cycle stability obviously decreased for x=100 alloy,and first declined and then augmented for the x=200 alloy with milling time extending.In addition,there was an optimal value with milling time varying for the high rate discharge abilities(HRD),which was 80.3%for x=100 alloys and 86.73%for x=200,respectively.     

熔盐法合成LiMn_（1/3）Ni_（1/3）Co_（1/3）O_2及AA电池的电化学性能

以KCl为熔盐,采用熔盐法合成了锂离子电池正极材料LiMn1/3Ni1/3Co1/3O2,扫描电子显微镜（SEM）显示此方法制备产物具有较好的晶形,颗粒较均匀.XRD表征结果显示产物为层状结构,充放电测试结果显示出材料在3.6 V平台附近有较大的可逆容量.在900℃时保温8 h时合成的LiMn1/3Ni1/3Co1/3O2具有较好的电化学性能,制作成AA电池,在2.75～4.2 V之间进行充放电测试,在1 C倍率下放电,LiMn1/3Ni1/3Co1/3O2的初始放电容量可达132.9 mAh/g,循环50多次后容量仍为124.6 mAh/g,容量保持率为93.75﹪.     

具有核壳结构的高电压正极材料Li(Co_(0.9)Ni_(0.05)Mn_(0.05))O_2的制备与表征

以共沉淀法制备的Ni-Mn包覆Co_3O_4前驱体和Li_2CO_3为原料,通过高温固相法制得了具有核壳结构的锂电池正极材料Li(Co_(0.9)Ni_(0.05)Mn_(0.05))O_2.用扫描电镜(SEM)、X射线能谱仪(EDS)、X射线衍射(XRD)和充放电测试表征了样品的形貌、晶体结构和电化学性能.结果表明,所制备的核壳结构Li(Co_(0.9)Ni_(0.05)Mn_(0.05))O_2具有良好的电化学性能,在3.0~4.5 V和3.0~4.6 V,0.2 C下首次放电容量分别达到180.5 m A·h·g~(-1)和201.3 m A·h·g~(-1),在1 C下,循环50周后容量保持率分别为89.3%和63.3%.     

Electrode Characteristics of MmNi_5－type Alloys for Nickel－metal HydrideBatteries

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Se掺杂介孔二氧化锰的合成及电化学性能研究

以介孔硅SBA-15为模板,硝酸锰作锰源,采用液相浸渍法,合成了介孔二氧化锰;在合成的过程中掺入硒粉,制备硒掺杂的介孔二氧化锰。采用XRD、SEM、TEM和BET等分析手段对样品的形貌和结构进行表征。结果表明:所合成的介孔二氧化锰与SBA-15具有相似的形貌和有序介孔结构;掺杂硒后,介孔二氧化锰的形貌和结构都没有明显的变化。为了研究样品的电化学性能,在9 mol/L KOH溶液中,250 mA/g的电流密度下放电。结果表明:介孔二氧化锰的放电容量达到344.26 mAh/g,比EMD增加119.7%。掺杂硒后,介孔二氧化锰的放电容量增大了,当掺硒量为5%时,介孔二氧化锰的放电容量最大,达到430.25 mAh/g,比EMD增加174.6%。     

包覆碳对LiFePO4正极材料性能的影响

采用二步固相法在750℃、24h的条件下合成了纯相的和包覆碳的LiFePO4锂离子正极材料,研究了包覆碳对材料性能的影响,并结合XRD、SEM和充放电测试等手段对合成材料的结构、形貌和电化学性能进行了分析。实验结果表明：LiFePO4／C正极材料具有更小的粒径和更紧密的颗粒分布,其中包覆碳为5％的材料电化学性能最好,首次放电比容量有129．6mAh／g,分别以0．2mA和1．0mA的电流充放电循环10次后其比容量保持在120．7mAh／g和92．0mAh／g,保持率分别达100．9％和95．2％。     

铌掺杂对镍基正极材料LiNi0.8Co0.1Mn0.1O2电化学性能影响

解决镍基正极材料LiNi_0.8Co_0.1Mn_0.1O₂的电化学循环稳定性和高温循环性能是其产业化推广应用的关键。研究了掺杂铌改性高镍正极材料,优化材料的电化学性能,提升循环稳定性。首先以硫酸盐为原料,在N₂保护气氛下,采用共沉淀法合成三元球形Ni_0.8Co_0.1Mn_0.1（OH）₂前驱体,通过高温固相反应与LiOH·H₂O,Nb₂O₅合成Li（Ni_0.8Co_0.1Mn_0.1）_1-xNb_xO₂（x=0,0.01,0.02,0.03）系列正极材料。X射线衍射结果表明,Nb5+离子可少量进入正极材料晶格,并在正极材料表面形成化学稳定性好的Li₃NbO₄。当x=0.02时,在室温25 ℃,电压2.75~4.2 V,0.2 C倍率下首次放电比容量为172.9 mAh/g,100次循环后容量保持率为97.47%,在50 ℃,0.5 C倍率下循环20次容量基本不变,平均放电比容量为183.7 mAh/g,且该样品具有较好的倍率性能。      

La0.8Mg0.2(Ni2.7Co0.6Al0.1Mn0.1)x贮氢合金的电化学性能分析

采用恒电位法、EIS分析及双电极系统对La0.8Mg0.2(Ni2.7Co0.6Al0.1Mn0.1)x(x=0.9～1.10)系列合金进行电化学性能分析。结果表明,x=1.05的合金具有较好的自放电性能(CR=97.3%),而x=1.10的合金有较高的电化学容量(369 mAh.g-1)。合金电极的电化学阻抗谱(EIS)表明,随着化学计量比x的增大,合金电极的电荷迁移电阻先减小后增大,动力学性能先增强后减弱。线性极化测试表明,随着化学计量比x的增大,合金电极表面的电化学反应速率先增大后减小。通过合金电极阳极电流对时间响应的半对数曲线计算的氢扩散系数D随着化学计量比x的增大先增大后降低,说明合金内部的氢扩散能力先增强后降低。     

镍氢电池负极用低成本储氢合金的研究

研究了ABS型储氢合金在低Co含量条件下，随B组元替代元素Co，Al，Si等含量的变化对合金电化学性能的影响规律，同时研究了A组元中不同La／Ce比对合金电化学性能的影响情况。结果表明，随合金中Co含量的降低，合金的活化性能和放电容量得以改善，但合金的循环寿命下降也比较明显；在试验范围内，随Al元素的加入，合金的循环寿命得以改善，但材料的放电容量和活化性能均有所下降；随合金La／Ce比的降低，合金的放电容量略有下降，但其循环寿命和放电电压平台有较大提高。