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在Ar气保护下采用磁悬浮感应熔炼方法,制备无CoLa1.8Ti0.2MgNi9-xAlx(x=0,0.1,0.2,0.3,0.4)合金,系统研究Al取代Ni对合金的结构及贮氢性能的影响。所有合金均包含LaMg2Ni9相,当Al含量x≥0.1,La(Ni,Al)5相取代LaNi5相、LaNi3相消失、LaNi2相出现。测试合金的焓变值与LaNi5合金(–30.6kJ/molH2)相近。Al取代Ni不仅提高合金电极的放电容量,而且改善循环稳定性及电化学动力学性能。La1.8Ti0.2MgNi8.7Al0.3合金贮氢性能较好,30℃下有效吸氢质量分数为1.32%;最大放电容量达到340mAh/g;1400mA/g放电电流密度下高倍率放电性能HRD1400高达79.8%;经100次充放电循环放电容量保持率为60%。
The effects of Al substitution Ni on the structure and hydrogen storage properties of the alloys were investigated systematically by magnetic induction melting under Ar gas protection without CoLa1.8Ti0.2MgNi9-xAlx (x = 0,0.1,0.2,0.3,0.4) alloys . All alloys contain LaMg2Ni9 phase. When the Al content is x≥0.1, the LaNi5 phase is replaced by La (Ni, Al) 5 phase, the LaNi3 phase disappears and the LaNi2 phase appears. The enthalpy change of the test alloy is similar to that of LaNi5 alloy (-30.6kJ / molH2). Al instead of Ni not only improve the discharge capacity of the alloy electrode, but also improve the cycle stability and electrochemical kinetics. The hydrogen storage capacity of La1.8Ti0.2MgNi8.7Al0.3 alloy is better, the effective hydrogen absorption mass fraction is 1.32% at 30 ℃, the maximum discharge capacity is 340mAh / g, and the high rate discharge performance HRD1400 at 1400mA / g discharge current density is as high as 79.8 %; After 100 charge-discharge cycle discharge capacity retention rate of 60%.