Designing and Surface Modification of Hydrogen Strage Alloy Material

由于镍氢电池的清洁性和高能量密度，储氢合金作为负极材料得到了广泛的研究。多种合金设计的可能性是储氢合金的特点之一。这种laes相合金、Mg-Ni体系和Ca-Ni体系合金的能量密度有望高于目前使用的基于稀土体系的储氢合金，因此作为下一代储氢材料具有很大的吸引力。本文对高频熔炼和机械磨削法制备的储氢合金负极的充放电特性进行了研究，结果如下：1) ab_2型laes相合金（A=Zr_<09>Ti_<01>， B=Ni_<055>Co_<0.05>Mn_<0.25>V_<0.1>Cr_<0.05>）经10 mol/dm^3 KOH溶液沸水处理1h后，表面活性显著提高，首次放电容量约为400 mAh g^<-1>。机械研磨使合金颗粒破碎，也有助于提高高速放电性能。2)机械合金MgNi和Ca_2Ni颗粒的放电容量分别为500 mAh g^<-1>和200 mAh g^<-1>。结果表明，MgO粉对MgNi的合金化有明显的促进作用，而石墨粉对MgNi的合金化有明显的抑制作用。3)机械合金Ti_2Ni负极的放电容量为l70mAh g_2。在500℃/ h下热处理后，合金的放电容量达到340 mAh / g_2。发现机械合金化与低温退火相结合是贮氢合金作为负极材料的一种很有前途的方法。

Extensive research on hydrogen storage alloys as a negative electrode material has been carried out, because of the cleanness and high energy density of nickel-hydride battery. The possibility of various alloy designings is one of the feature of hydrogen storage alloy. Such Laves-phase alloys, Mg-Ni system and Ca-Ni system alloys are attractive as a material for the next generation because the energy density is expected to be larger than that of currently used hydrogen storage alloys based on rare earth system. In this study, charge and discharge characteristics ofnegative electrode consisting of more promising hydrogen storage alloys prepared by high frequency melting and mechanical grinding were evaluated, The results are summarized as follows.1)The surface modification of AB_2-type Laves-phase Alloy (A=Zr_<09>Ti_<01>, B=Ni_<055>Co_<0.05>Mn_<0.25>V_<0.1>Cr_<0.05>) with 10 mol/dm^3 KOH solution at boiling temperature for 1h remarkably improved the initialsurface activity leading to the first discharge capacity of ca. 400 mAh g^<-1>. Fragmentation of the alloy particles by mechanical grinding also contributed to an increase in high-rate dischargeability.2)The discharge capacities of mechanically alloyed MgNi and Ca_2Ni particles were found to be 500 mAh g^<-1> and 200 mAh g^<-1>, respectively. It was confirmed that MgO powder accelerated the process of mechanical alloying, but graphite powder strongly inhibited the alloying of MgNi.3)The discharge capacity of mechanically alloyed Ti_2Ni negative electrode was found to be l70mAh g_2. The discharge capacity of the alloy increased to 340 mAh g_2 by heat-treatment at 500ﾟC for lh. The combination of mechanical alloying and low-temperature annealing was found to be promising method for hydrogen storage alloy used for the negative electrode material.