LaNi_(3.15-x)Mn_xCo_(0.25)Al_(0.1)储氢合金结构及电化学性能

为了研究Mn替代Ni对AB3.5型储氢合金结构及电化学性能的影响,采用电弧炉熔炼制备LaNi3.15-xMnxCo0.25Al0.1合金。采用XRD、SEM等材料分析方法以及恒电流充放电等电化学测试技术,研究LaNi3.15-xMnxCo0.25Al0.1(0≤x≤0.3)合金的结构和电化学储氢性能。结果表明:LaNi3.15-xMnxCo0.25Al0.1(0≤x≤0.3)合金由多相组合形成,合金的主相为LaNi5和La2Ni7;随着Mn替代Ni含量的增加,LaNi5相中a轴和c轴以及晶胞体积增加;合金电极的最大放电容量有所升高,由x=0的238mA·h/g逐渐增加到x=0.3的277.1mA·h/g;高倍率性能随着Mn含量的增加先升高后降低,在x=0.2时合金的高倍率性能最佳。

Microstructure and electrode performance of LaNi3.15-xMnxCo0.25 Al0.1 hydrogen storage alloys

Mn was used for partial substitution Ni in order to improve the structure and electrochemical properties of the hy-drogen storage LaNi3.15-xMnxCo0.25Al0.1（0≤x≤0.3）,LaNi3.15-xMnxCo0.25Al0.1（0≤x≤0.3）alloys were prepared by mag-netic levitation melting.A series of experiments were performed to study microstructure and electrode properties of La-Ni3.15-xMnxCo0.25 Al0.1 （0≤x≤0.3）alloys with X-ray diffraction （XRD）and scanning electron microscopy （SEM）.The XRD spectroscopy shows that all the composites are mainly composed of La2 Ni7 phase and LaNi5 phase.The apparent in-crease of lattice parameters （a,c and V）has been observed with the increase of Mn content.With the increase of Mn con-tent,the maximum discharge capacity increases from 238 mA·h/g （x=0）to 277 mA·h/g（x=0.3）.The discharge ca-pacity increases firstly and then decreases with the increase of Mn content.The performance of alloys is best when x=0.2.