CoZnB添加量对稀土基储氢合金电化学性能的影响

Effects of CoZnB Addition on Electrochemical Properties of Rare Earth-based Hydrogen Storage Alloys

首先采用化学还原法制备了CoZnB非晶合金,随后用机械球磨法将其引入到稀土基合金La_(0.7) Mg_(0.3)Ni_(3.5)中制备成复合物,考察了CoZnB的添加量对La_(0.7) Mg_(0.3)Ni_(3.5)合金电化学性能的影响。实验结果表明,加入CoZnB非晶合金后,复合物合金电极首次放电即可达到最大放电容量,高倍率放电性能得到了显著改善,电荷转移阻抗和极限电流密度均高于La_(0.7) Mg_(0.3)Ni_(3.5)合金电极。复合物合金电极La_(0.7) Mg_(0.3)Ni_(3.5)-CoZnB(质量比1∶1)的最大放电容量高达487.5mAh/g,800mA/g放电电流密度下的复合物合金电极La_(0.7) Mg_(0.3)Ni_(3.5)-CoZnB(质量比2∶1)的高倍率放电性能(HRD)可达94.8%。

CoZnB amorphous alloy was synthesized via a chemical reduction method and then introduced into a rare earth-based alloy La_（0.7） Mg_（0.3）Ni_（3.5） to form the composites by ball milling.The effect of CoZnB concentration on the electrochemical properties of the La0.7Mg0.3Ni3.5alloy was systematically investigated.The experimental results show that the maximum discharge capacity of the composite electrodes can be achieved at their first charge/discharge cycle and the high rate dischargeability is remarkably improved.Moreover,the charge-transfer reaction resistance and the limiting current density of the composite electrodes are higher than those of the La_（0.7） Mg_（0.3）Ni_（3.5） alloy electrode.The maximum discharge capacity of La_（0.7） Mg_（0.3）Ni_（3.5）-CoZnB（in a weight ratio of 1∶1）has a high value of 487.5mAh/g and the high rate dischargeability（HRD）of La_（0.7） Mg_（0.3）Ni_（3.5）-CoZnB（in a weight ratio of 2∶1）at 800mA/g is 94.8%.