热处理温度对LaNi3.8Al1Mn0.2合金储氢性能的影响

对热处理(1173K, 1223K, 1273K, 1323K)前后LaNi3.8Al1.0Mn0.2合金的研究表明,热处理前后合金均由一个主相,三种第二相组成。热处理后第二相后变小,分布更加弥散,第二相中LaNi2变为LaNi相,晶胞参数和晶胞体积增加,活化性能变差,但吸放氢平台压降低,吸放氢平台的斜率和滞后变小,合金的吸氢速度显著变快,吸放氢焓变和吉布斯自由能的绝对值增大,而吸氢量未见明显变化。随着热处理温度的升高,晶胞参数和晶胞体积先增大后减小,吸放氢平台压先降低后升高,斜率先增大后减小,滞后先减小后增大,而焓变和自由能的绝对值先增加后减小,在1223K分别达到最大和最小值,而热处理温度的升高使活化性能和动力学性能略有提升。     

Electrochemical characteristics of an amorphous Mg0.9V0.1Ni alloy prepared by mechanical alloying

Electrochemical characteristics of an amorphous MgNi alloy with Mg partially substituted by V were investigated. A Mg_0.9V_0.1Ni alloy prepared by mechanical alloying (MA) exhibited much better cycle life than MgNi alloy. It was found that the partial substitution of Mg in MgNi with V could suppress the formation of Mg(OH)₂ on the alloy surface during the charge–discharge cycling in alkaline solution. This may have unveiled an important factor to improve cycle life of the Mg-based alloy for use in nickel–hydrogen batteries.     

Fabrication characteristics and hydrogenation behavior of hydrogen storage alloys for sealed Ni−MH batteries

Hydrogen storage alloys based on LmNi_4.2Co_0.2Mn_0.3Al_0.3 were fabricated to study the equilibrium hydrogen pressure and electrochemical performance. The surface morphology and structure of the alloys were analyzed by SEM and XRD, and then the hydrogenation behaviors of all alloys were evaluated by PCT and electrochemical half-cell. We studied the hydrogenation behavior of the Lm-based alloy with changes in composition elements such as Mn, Al, and Co and investigated the optimal design for Lm-based alloy in a sealed battery system. As a result of studying the hydrogenation characterization of alloys with the substitution elements, hydrogen storage alloys such as LmNi_3.75Co_0.15Mn_0.5Al_0.3 and LmNi_3.5Co_0.5Mn_0.5Al_0.5 were obtained to correspond with the characteristics of a sealed battery with a higher capacity, long life cycle, lower internal pressure, and lower battery cost. The capacity preservation rate of LmNi_3.5Co_0.5Mn_0.5Al_0.5 was greatly improved to 92.7% (255 mAh/g) at 60 cycles, indicating a low equilibrium hydrogen pressure of 0.03 atm in PCT devices.     

铸态及快淬态无钴AB5型贮氢合金的循环稳定性

对AB5型LaxMm1-x(NiMnSiAlFe)49(x=0,0.45,0.75,1.00,摩尔分数)贮氢合金进行了快淬处理,研究了La含量及快淬工艺对合金微观结构及电化学循环稳定性的影响.结果表明:La含量的增加对铸态合金的循环稳定性没有明显影响,但使快淬态合金的循环稳定性下降,且快淬处理能显著提高合金的循环稳定性.当La替代量从0增加到1.00时,经300次充放循环后,铸态合金的容量保持率(Rh)从59.2%增加到59.8%;16 m/s淬速快淬态合金的容量保持率从83.9%下降到65.0%.对于x=0.45的合金,当淬速从0(铸态被定义为淬速等于0)增加到28 m/s时,容量保持率从59.8%增加到75.8%.     

Activation of hydrogen storage materials in the Li–Mg–N–H system: Effect on storage properties

We investigate the thermodynamics, kinetics, and capacity of the hydrogen storage reaction: Li₂Mg(NH)₂ + 2H₂  Mg(NH₂)₂ + 2LiH. Starting with LiNH₂ and MgH₂, two distinct procedures have been previously proposed for activating samples to induce the reversible storage reaction. We clarify here the impact of these two activation procedures on the resulting capacity for the Li–Mg–N–H reaction. Additionally, we measure the temperature-dependent kinetic absorption data for this hydrogen storage system. Finally, our experiments confirm the previously reported formation enthalpy (ΔH), hydrogen capacity, and pressure–composition–isotherm (PCI) data, and suggest that this system represents a kinetically (but not thermodynamically) limited system for vehicular on-board storage applications.