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.
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.