La4-xPrxMgNi19（x=0～2．0）贮氢合金的相结构与电化学性能

Phase Structure and Electrochemical Properties of Hydrogen Storage Alloys La4-xPrxMgNi19（x=0～2.0）

系统研究了Pr替代La后对La4-xPrxMgNi19（x=0～2．0）贮氢合金的相结构与电化学性能影响。结构分析表明，合金主要由Pr5Co19、Ce5Co19、CaCu5型物相组成。随着x的增加，合金中A5B19（Pr5Co19＋Ce5Co19）型物相逐渐增多，同时各物相的晶胞参数（a，c）和晶胞体积（V）均呈线性减小。电化学测试表明，随着X的增加，合金活化性能显著降低，合金贮氢量先增加后减少，但合金循环寿命有所提高。合金的高倍率放电性能（且舳）随着X的增加先增加后减少，在x=1．2时有最大值（HRD900=94．77％）。合金的HRD主要由合金表面的电催化活性所控制。

The phase structure and electrochemical properties of La4-xPrxMgNi19（x=0～2.0） alloys have been systematically investigated in this paper. The structure analysis of alloys shows that the alloys are mainly composed of multiphase, such as Pr5co19 phase, CesCo19 phase, and CaCu5 phase. The increase of Pr in the alloys leads to the increase of A5B19 （Pr5co19 ＋Ce5Co19） type phases, at the same time, also the decrease of lattice parameters and cell volume. The electrochemical Study indicates that the maximum discharge capacity of alloy electrodes decreases firstly and then increases, the activation properties decreases, but the cyclic stability of alloys is improved with the increase of Pr content. In addition, the high rate discharge ability （HRD） of alloy electrodes increases firstly and then decrease with increasing x. The alloy with x=1.2 shows the best high rate discharge ability （HRD）. The HRD of alloys is mainly controlled by the charge-transfer activity on the surface.