球磨CNTs导电剂对AB_5型储氢合金电极电化学性能的影响

Effects of ball-milled CNTs as conductive agent on electrochemical properties of AB_5-type hydrogen storage alloy electrode

采用X射线衍射(XRD)和扫描电镜(SEM)研究不同球磨时间下多壁碳纳米管(CNTs)的微观结构。XRD分析表明:随着球磨时间的延长,CNTs的衍射峰明显变弱,并伴有部分衍射峰消失。SEM结果发现:球磨使细长的CNTs断裂,长度明显变短;随球磨时间的进一步延长,CNTs空心管状结构破损。采用电化学方法测试添加未球磨和球磨不同时间CNTs导电剂的AB5型储氢合金电极的电化学性能。结果表明:随球磨时间的延长,合金电极的最大放电容量、放电性能及循环稳定性均呈现出先提高后减弱的变化规律。当CNTs的球磨时间为2 h时,合金电极的最大放电容量和放电性能达最佳;当CNTs的球磨时间为2.5 h时,合金电极的循环稳定性最佳。

The microstructures of carbon nanotubes （CNTs） after milling for different time were characterized by XRD and SEM. XRD analysis results indicate that the intensity of the diffraction peaks of the milled carbon nanotubes signi？cantly decreases with increasing milling time. In addition, as the milling time increasing, all diffraction peaks gradually weaken and some peaks disappear. SEM observations show that ball milling is a good method to cut long CNTs into short ones. The tubular structure of CNTs is destroyed after milling for a long time. The electrochemical properties of AB5-type alloy electrodes added unmilled and milled CNTs were investigated. The results indicate that the maximum discharge capacities, discharge properties and cycle stabilities of the alloy electrodes improve firstly, and then degenerate with increasing of ball-milling time. The alloy electrode added CNTs milling for 2 h exhibits the best discharge capacity and discharge property. The alloy electrode added CNTs milling for 2.5 h shows the best cycle stability.