【摘要】 采用二步熔炼法制备了Mm(NiCoMnAl)5/5%(质量分数)Mg2Ni复合储氢合金,并对其在不同温度(1023、1123和1223K)下进行退火热处理10h。用X射线衍射(XRD)、扫描显微镜(SEM)和电化学测试方法研究了退火温度对合金结构和电化学性能的影响。结果表明,铸态Mm(NiCoMnAl)5/5%(质量分数)Mg2Ni复合合金由LaNi5相和少量的Mg2Ni相组成,而退火态合金由LaNi5相和(La,Mg)Ni3新相组成。合金的最大放电容量和高倍率放电性能随退火温度的升高呈现出先增强后减弱的变化规律,其中退火温度为1023K时,合金电极的上述性能均达到最佳。合金的容量保持率随退火温度的升高而单调地增大,60次充放电循环后容量保持率从铸态合金的86.6%增大到退火合金(1223K)的92.4%。更多还原

【Abstract】 Mm( NiCoMnAl) 5/5wt% Mg2 Ni composite hydrogen storage alloys were prepared by two-step remelting and then annealed at 1023,1123 and 1223K for 10h. The effect of annealing temperature on the microstructure and electrochemical properties of Mm( NiCoMnAl)5/5wt% Mg2 Ni were investigated by means of X-ray diffraction( XRD),scanning electron microscope( SEM),and electrochemical measurements. The results showed that the as-cast composite alloy was composed of the LaNi5 phase and a small amount of the Mg2 Ni phase. However,the annealed alloys consisted of the LaNi5 phase and a( La,Mg) Ni3 new phase. The maximum discharge capacity and high rate dischargeability of the alloys increased firstly and then decreased with increasing annealing temperature. The alloy annealed at 1023K exhibited the best the maximum discharge capacity and high rate dischargeability. The capacity retention increased monotonically with the increase of annealing temperature,and the capacity retention of the alloy increased from 86. 6%( as-cast) to 92. 4%( annealed at 1223K) after 60 charge-discharge cycles.更多还原