球磨时间对AB_5/10wt.%CNTs复合储氢合金电化学性能的影响

Effect of Milling Time on the Electrochemical Properties of AB_5/10 wt.% CNTs Composite Hydrogen Storage Alloys

将Mm(NiCoMnAl)5合金与CNTs均匀混合后机械球磨制备Mm(NiCoMnAl)5/10wt.%CNTs复合储氢合金.用X射线衍射(XRD)、扫描电镜(SEM)和电化学测试方法研究复合合金的结构和电化学性能.结果表明:Mm(NiCoMnAl)5/10wt.%CNTs复合合金主要具有CaCu5结构,在其表面键合了众多的CNTs.随球磨时间增大,复合合金中CNTs含量逐渐减少.复合合金的最大放电容量、循环稳定性和高倍率放电性能随球磨时间的增大呈现出先增大后减小的变化规律,其中球磨时间为5h时,最大放电容量达到最大值291.9mAh/g;当球磨时间为3h时,合金电极经60次充放电循环后的容量保持率高达91.2%,且具有最佳的高倍率放电性能.

Mm（ NiCoMnA1）5/10wt. % CNT composite hydrogen storage alloys are prepared by ball milling Mm（NiCoMnA1） 5 with a small amount of CNTs as addition under an atmosphere of high purity ar-gon. Structures and electrochemical properties of the composite alloys are investigated systematically by X-ray diffraction, scanning electron microscope and electrochemical experiments. The results indicate that the composite alloys possess a structure of CaCu5 on whose surface a plenty of CNTs are bonded. The content of CNTs in composite alloys decreases with increasing milling time. The electrochemical studies show that maxi-mum discharge capacity, the capacity retention after 60 cycles and high rate discharge-ability of the compos-ite alloys increase firstly and then decrease with increasing milling time. The alloy milled for 5 h exhibits the best maximum discharge capacity （291.9 mAh/g）. And the alloy milled for 3 h is the best capacity reten-tion after 60 charge-discharge cycles （91.2%） and high rate dischargeability.