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用感应熔炼法制备了La0.5Pr0.2Nd0.1Mg0.2(Ni0.85-xCo0.15Alx)3.5(x=0.01~0.04)合金,并在氩气气氛下,用900℃退火处理。XRD分析表明,合金有两个主相:La2Ni7相和LaNi5相,晶轴比c/a随着Al含量的增大而增大。电化学测试表明,放电容量随着Al含量的增大而减小,由x=0.01时的394.6mAh/g下降到x=0.04时的380.6mAh/g,充放电循环衰减速率由x=0.01时的–0.32mAh/(g·cycle)降为x=0.04时的–0.20mAh/(g·cycle),合金的倍率性能随着Al含量的增大而降低,当放电电流密度为1200mA/g时,高倍率性能由x=0.01时的61%降为x=0.04的35%。研究表明,当x≤0.02时不仅保持了合金的高容量,而且明显改善了合金的循环性能。
The La0.5Pr0.2Nd0.1Mg0.2 (Ni0.85-xCo0.15Alx) 3.5 (x = 0.01-0.04) alloy was prepared by induction melting method and annealed at 900 ℃ under an argon atmosphere. XRD analysis shows that the alloy has two main phases: La2Ni7 phase and LaNi5 phase, and the ratio of crystal axis c / a increases with the increase of Al content. Electrochemical tests showed that the discharge capacity decreased with the increase of Al content from 394.6mAh / g at x = 0.01 to 380.6mAh / g at x = 0.04. The decay rate of charge-discharge cycle from x = 0.01 -0.32mAh / (g · cycle) to -0.20mAh / (g · cycle) when x = 0.04. The rate performance of the alloy decreases with the increase of Al content. When the discharge current density is 1200mA / g , The high-rate performance is reduced from 61% at x = 0.01 to 35% at x = 0.04. The research shows that when x≤0.02, not only the high capacity of the alloy is maintained, but also the cycling performance of the alloy is obviously improved.