La_(0.7)Zr_(0.1)Mg_(0.2)Ni_(3.4-x)Co_xFe_(0.1)合金的制备与电化学性能研究

Preparation and Electrochemical Properties of La_(0.7)Zr_(0.1)Mg_(0.2)Ni_(3.4-x)Co_xFe_(0.1) Alloy

在氩气保护下采用电磁感应熔炼制备La0.7Zr0.1Mg0.2Ni3.4-xCoxFe0.1(x=0.15,0.25,0.35,0.45)合金,研究合金的相结构,以及Co元素部分取代Ni元素对合金的气态储氢性能和电化学性能的影响。结果表明,合金主要由LaNi5、LaNi2以及La2MgNi9相组成。合金电极的最大放电容量分别为346.7mAh/g(x=0.15)、320.3mAh/g(x=0.25)、363.0mAh/g(x=0.35)和313.3mAh/g(x=0.45),经过65个充放电循环后,合金电极的容量保持率从63.0%(x=0.15)增加到80.2%(x=0.35),然后再下降到75.0%(x=0.45)。La0.7Zr0.1Mg0.2Ni3.15Co0.25Fe0.1合金具有较高的高倍率放电性能(HRD1200%=67.3)和较大的极限电流密度(IL=386.8 mA/g),显示出其良好的电化学动力学性能。

La0.7Zr0.1Mg0.2Ni3.4-xCoxFe0.1（x=0.15,0.25,0.35,0.45） alloys were prepared by electromagnetic induction melting under Ar atmosphere.The results showed that the alloys were mainly composed of LaNi5,LaNi2 and La2MgNi9 phases.The electrochemical measurements showed that the maximum discharge capacity of the alloy electrodes were 346.7mAh/g（x=0.15）,320.3mAh/g（x=0.25）,363.0mAh/g（x=0.35） and 313.3mAh/g（x=0.45）,respectively.The cyclic capacity retention rate C65/Cmax of alloy electrodes first increased to 80.2%（x=0.35） from 63.0%（x=0.15）,and then decreased to 75.0%（x=0.45）.For La0.7Zr0.1Mg0.2Ni3.15Co0.25Fe0.1 alloy,the high rate dischargeability was 67.3% and the limiting current density was 386.8mA/g.These results indicated that the electrochemical kinetics and performance of La0.7Zr0.1Mg0.2Ni3.15Co0.25Fe0.1 alloy were better among La0.7Zr0.1Mg0.2Ni3.4-xCoxFe0.1（x=0.15,0.25,0.35,0.45） alloys.