氮气热处理对CNTs-LaNi5电极电化学性能的影响

研究了碳纳米管(CNTs)氮气热处理后结构的变化, 以及热处理温度对CNTs-LaNi5电极电化学性能的影响. CNTs热处理后, 管壁变薄, 层数变少, 管的外径减小, 更有利于氢气的吸附和脱附. 将碳纳米管与LaNi5储氢合金按质量比1:10混合, 制作成CNTs-LaNi5电极. 800 ℃时CNTs-LaNi5电极的储氢性能最好, 最大容量为519.1 mAh•g-1, 相应的平台电压高达1.19 V. 在500～600 ℃范围内, 随着温度升高, 放电容量有较大幅度的增加; 在600～800 ℃范围内, 随着温度升高, 放电容量有较小幅度的增加; 但到900 ℃时, 放电容量反而下降. 由此可见, CNTs的热处理温度对CNTs-LaNi5电极的电化学储氢性能有着较大的影响. 纯LaNi5电极的放电容量仅为265.6 mAh•g-1, 平台电压仅为0.83 V. 添加了碳纳米管的CNTs-LaNi5电极的电化学活性高于纯LaNi5电极.

Effect of CNTs Treated at Different Temperatures in Nitrogen Ambient on the Electrochemical Properties of CNTs-LaNi5 Electrodes

The structure change of carbon nanotubes (CNTs) after heat treatment and the effect of CNTs treated at different temperatures in nitrogen ambient on the electrochemical properties of CNTs-LaNi5 electrodes were investigated. The thickness of CNTs after heat treatment is thinner, the number of layers is less and the outside diameter is smaller than those unheated of CNTs. So the deposition and release of hydrogen are easier. CNTs-LaNi5 electrodes were prepared by mixing CNTs and LaNi5 alloy in a mass ratio of 1:10. The CNTs-LaNi5 electrodes with CNTs treated at 800 ℃ in nitrogen has the best electrochemical hydrogen storage capacity with a highest capacity of 519.1 mAh•g-1 and a corresponding discharging plateau voltage of 1.19 V. From 500 ℃ to 800 ℃, the higher the temperature of the heat treatment is, the better the electrochemical hydrogen storage property of the electrode will be. However, CNTs-LaNi5 electrodes with CNTs treated at 900 ℃ has a lower capacity. This shows that the temperature of treatment is an important factor that influences electrochemical hydrogen storage performance of CNTs. Pure LaNi5 electrode has a discharge capacity of only 265.6 mAh•g-1 and a discharging plateau voltage of only 0.83 V, which are lower than those of all CNTs-LaNi5 electrodes treated at different temperatures in nitrogen ambient.