La1-xPrxNi4.2Mn0.3Al0.3Cu0.15Fe0.05电化学性能储氢合金结构及

为改善无钴AB，储氢合金La1-xPrxNi4.2Mn0.3Al0.3Cu0.15Fe0.05的循环性能，采用XRD、SEM等分析方法以及恒电流充放电等电化学测试技术，研究了系列La1-xPrxNi4.2Mn0.3Al0.3Cu0.15Fe0.05（x=0-0．3）合金的结构和电化学储氢性能。结果表明：制备的合金为单一的CaCu，结构，随着Pr替代La含量的增加，晶胞的口轴、C轴和晶胞体积均逐渐减小，c／a值逐渐增大。相应合金的放电容量有所降低，但合金电极的循环稳定性和高倍率放电性能得到明显改善。100个循环后的容量保持率S100分别为47．28％（x=0）、48．22％（乒0．1）、50．79％（x=0．2）和54．47％（x=0.3）。在放电电流为1800mA／g的条件下，合金电极的高倍率性能45．13％（x=0）升高到56．19％（x=0．3）。合金电极的交换电流密度厶随Pr含量的增加而逐渐增大，而合金电极的氢扩散系数DH没有明显变化。

Microstructure and Electrochemical Performance of La1-xPrxNi4.2Mn0.3Al0.3Cu0.15Fe0.05 Hydrogen Storage Alloys

To improve the cycle stability of Co-free hydrogen storage alloy La1-xPrxNi4.2Mn0.3Al0.3Cu0.15Fe0.05, several experiments were performed to study microstructure and electrochemical properties of La1-xPrxNi4.2Mn0.3Al0.3Cu0.15Fe0.05（X=0~0.3） alloys with X-ray diffraction（XRD）, scanning electron microscopy（SEM） and simulated battery test method. Results show that the prepared alloys are all single-phase alloys with a hexagonal CaCu5 structure（LaNi5 phase）. An apparent decrease of lattice parameters （a,c and V） has been observed with the increase of Pr content（x）. While the maximum capacity decreases, the cycle stability and the high rate discharge（HRD） performance are improved. The capacity retention after 100 cycles S,0o increases from 47.28%（x=0） to 48.22%（x= 0.1）, 50.79%（x=0.2） and 54.47%（x=0.3）. Meanwhile, the HRD performance will be improved gradually from 45.13%（x=0） to 56.19%（x=0.3） when the discharge current density is 1800 mA/g. Furthermore, the exchange current density 10 increases obviously with the increase of Pr content, while the variety of hydrogen diffusion coefficient DH is inconspicuous.