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采用X射线衍射、电子探针和电化学测试研究了La2Mg1-xAlxNi7.5Co1.5(x=0.0,0.1,0.3,0.5)合金的相结构和电化学性能。XRD结果和EPMA观察表明,少量的Al替代Mg(x=0.1)不改变La2MgNi7.5Co1.5合金的相组成,合金仍然由LaNi3相和αLa2Ni7相组成,然而La2Mg0.9Al0.1Ni7.5Co1.5合金中LaNi3相的丰度明显下降,αLa2Ni7相的丰度则增加,较多的Al替代Mg改变了La2MgNi7.5Co1.5合金的相组成并导致合金中LaNi3相消失,La2Mg1-xAlxNi7.5Co1.5合金中Al含量的变化对合金中不同相晶胞参数的影响不相同。此外,少量的Al替代Mg(x=0.1)几乎不降低La2MgNi7.5Co1.5合金的贮氢容量和最大电化学放电容量,但随La2Mg1-xAlxNi7.5Co1.5合金中Al含量的增加,合金的贮氢容量、最大电化学放电容量和活化性能不断下降,Al替代Mg能明显提高La2MgNi7.5Co1.5合金的电化学循环稳定性,对提高该合金电极的高倍率放电性能也是有利的。
The phase structure and electrochemical properties of La2Mg1-xAlxNi7.5Co1.5 (x = 0.0,0.1,0.3,0.5) alloys were investigated by X-ray diffraction, electron probe and electrochemical measurements. XRD results and EPMA observations show that a small amount of Al instead of Mg (x = 0.1) does not change the phase composition of La2MgNi7.5Co1.5 alloy, the alloy is still composed of LaNi3 phase and αLa2Ni7 phase, but La2Mg0.9Al0.1Ni7.5Co1.5 alloy The abundance of LaNi3 phase decreased significantly and the abundance of αLa2Ni7 phase increased. The substitution of more Al for Al changed the phase composition of La2MgNi7.5Co1.5 alloy and led to the disappearance of LaNi3 phase in the alloy. La2Mg1-xAlxNi7.5Co1.5 alloy Al content changes in the alloy phase cells of different parameters are not the same. In addition, a small amount of Al instead of Mg (x = 0.1) almost does not reduce the hydrogen storage capacity and maximum electrochemical discharge capacity of La2MgNi7.5Co1.5 alloy, but with the increase of Al content in La2Mg1-xAlxNi7.5Co1.5 alloy, Hydrogen storage capacity, the maximum electrochemical discharge capacity and activation properties continue to decline, Al substitution Mg can significantly improve the electrochemical cycling stability of La2MgNi7.5Co1.5 alloy, to improve the high rate discharge of the alloy electrode performance is also beneficial.