MmB5贮氢合金的结构和性能

近十年未对AB5型合金的研究表明，某些多元取代的LaNi5基合金可作为MH／Ni电池的负极材料，且具有容量大，寿命长等优点[1，2]．LaNi5虽然具有吸放氢量较大、平台氢压平整和压力滞后小等优良性能，但不耐硷腐蚀、吸氢后易粉化，其氢化物的分解氢压较高，故不能作为负板材料．以Co部分地取代Ni可有效地降低氢化物的分解氢压·混合稀土（Mm）取代La，虽容量有所下降，但从原料成本上看是有益的．本工作试图从MmB5多元合金晶体结构的研究，来探讨Mm中La和Ce的相对含量对吸放氢性能和电化学容量的影响．1实验Mllin。合金样品由金属Ni，…

Crystal Structure and Hydrogen Absorption Properties of MmB_5 Alloys

Pressure composition isotherms, crystal structures and electrochemical capacities of MmB5 alloy-hydrogen systems have been investigated, where Mm represents La-rich mischmetals and B5 take a composition of Ni3.8Co0.5Mn0.4Al0.3. All these multicomponent alloys belong to CaCu5-type hexagonal crystal structuxe. The volume of unit cell (or say,the interstitial hole size) becomes larger with increasing of La content and decreasing of Ce content in Mm. The larger interstitial hole leads to a decrease of dissociation pressure of their hydride, hence improves the stability of MmB5H6 and the electrochendcal capacity of the MmB5 alloy. The expansion ratio of the MmB5 for hydrogen absorption was obviously smaner than that of LaNi5 alloy. For MmB5 alloy, especially with high content of La in Mm, a lot of properties for the application in MH/Ni battery, such as against pulverization, long cycle lifetime etc can be promoted.