镧取代对镁基贮氢合金的影响及其电化学性能研究

Effect of Substituting La for Mg and Electrochemical Characteristics of Mg-Based Hydrogen Storage Alloys

用机械球磨法(MA)合成了Mg0.9LaxAl0.1-xNi(x=0.015,0.02,0.025,0.03)系列合金。充放电性能测试表明金属Mg被La取代后,合金放电容量的衰减变缓,最高放电容量为418.64 mAh.g-1,30周以后仍能达到161.41 mAh.g-1。XRD结构分析表明,在球磨初期仍为晶态,随着球磨时间的增加,逐渐变为非晶态,此时放电容量达到最大。循环伏安和交流阻抗测试结果表明当La的取代含量为0.025时电化学容量最高,循环可逆性好且电极表面电子转移电阻即电化学反应电阻最小。

The Mg0.9LaxAl0.1-xNi（x = 0.015, 0.02, 0. 025, 0.03） were synthesized by MA, with partial substitution of La for Mg, in order to slower deterioration of discharge capacity. The results show that the maximum discharge capacity gets to 418.64 mAh·g^-1 by the La partial substituting, the discharging plateau becomes little gently, the discharge capacity still get to 161.41 mAh·g^-1 and deterioration becomes slower with circulation improved. The X-ray diffraction indicates that alloys still are crystal initially and become amorphous with increase of milling time, meanwhile, discharge capacity gets its maximum. The electrochemical characteristics of alloys were also studied by means of cyclic vohammogram and AC impedance spectra.