CNTs添加对MmMn0.4Co0.7Al0.3Ni3.4贮氢合金负极性能的影响

对商用MmMn0．4Co0．7Al0．3Ni3．4贮氢合金中添加多壁碳纳米管（CNTs）、Ni的电化学性能进行了研究，结果表明，CNTs的加入可以提高电极的放电容量和初始活化性能，合金中添加CNTs、CNTs＋Ni的电极完全活化只需11个循环，其最大放电容量分别为255、271mAh／g．而添加Ni的电极则需24个循环才达到最大容量（245mAh／g）；合金中添加CNTs、CNTs＋Ni的电极具有更高的放电平台和更好的高倍率放电性能（HRD），在1000mAh／g放电电流下，添加CNTs、CNTs＋Ni、Ni以及未添加电极的HRD值依次为80．5％、83．9％、66．9％和62．4％，线性极化和电化学阻抗测试表明，CNTs的加入可有效减少欧姆电阻、提高电极表面的电荷迁移速率，更有利于在大电流下进行放电。

Effects of Addition of Carbon Nanotubes on Properties of MmMn0.4Co0.7Al0.3Ni3.4 Hydrogen Storage Electrode

The electrochemical properties of MmMn0.4Co0.7Al0.3Ni3.4 hydrogen storage electrode with CNTs and Ni additives were invesitigated. The results show that the addition of CNTs in the alloys improves the discharge capacity and initially activation performance. The alloy electrodes with CNTs, CNTs+Ni additives can be completely activated after 11 charge-discharge cycles with maximum capacity of 255.1 and 270.5 mAh/g, respectively. However, activation process of the electrode containing Ni powder needs 24 cycles and the maximum capacity is 245.0 mAh/g accordingly. And also, the addition of CNTs, CNTs+Ni in the alloys modifies the high-rate dis-chargeability(HRD) performance and reveals the higher discharge voltage. The HRD of electrodes with CNTs, CNTs+Ni, Ni and without any additives are 80.5%, 83.9%, 66.9% and 62.4% at the discharge current of 1000 mAh/g, respectively. From their kinetics analysis of linear polarization curve and electrochemical impedance spectroscopy, the addition of CNTs in the alloys decreases the ohmic resistance and improves the rate of charge transfer reaction on the surface, and contributes to the discharge under the high current conditions.