Mg_(0.9-x)Ti_(0.1)Pd_xNi(x=0.04～0.1)贮氢合金电极腐蚀行为研究

The Corrosion Behaviors of Mg_(0.9-x)Ti_(0.1)Pd_xNi(x=0.04～0.1)Hydrogen Storage Alloy Electrodes

研究了Pd部分替代Mg对Mg0.9-xTi0.1PdxNi(x=0.04～0.1)贮氢合金腐蚀性能的影响.利用机械合金化方法制备了Mg0.9-xTi0.1PdxNi(x=0.04～0.1)贮氢合金.XRD和TEM分析表明经120h球磨后该合金完全非晶化.循环充放电测试结果表明,Pd的替代有效地延长了Mg0.9-xTi0.1PdxNi(x=0.04～0.1)合金的循环寿命.采用开路电位测量,阳极极化,电化学阻抗和X射线光电子能谱研究了该合金的腐蚀行为.结果表明,随着Pd含量增加,合金腐蚀电位正移,初始腐蚀电流下降,腐蚀电流增加的速度变缓.采用本文提出的等效电路模型较好地拟合了合金的电化学阻抗谱.分析表明,随着Pd含量的增加,合金表面钝化膜厚度和电阻逐渐增大.X射线光电子能谱分析表明,Pd的加入减弱了合金在充放电过程中的氧化程度.当Pd含量达到0.1时,Mg0.9-xTi0.1PdxNi(x=0.04～0.1)合金的耐腐蚀性能最好,其放电容量保持率最高.

The effects of partial substitution of Pd for Mg on the corrosion behaviors of Mg0.9-xTi0.1PdxNi（x=0.04～0.1） hydrogen storage alloys were studied in this paper. The alloys were prepared by mechanical alloying. The alloy structures became amorphous after ball milling 120 h, which was confirmed by XRD and TEM analyses. The cyclic charge-discharge tests showed that the Pd addition prolonged the cycle life of the alloys effectively. The corrosion performances of the alloys were investigated by open circuit potential measurements, anodic polarization, electrochemical impedance spectroscopy, and XPS experiments. The increase of Pd content shifted the alloy corrosion potentials towards more positive values. The initial corrosion currents of the alloys and its increment rates along with cycle number decreased with the increase of Pd content in the alloys. The measured electrochemical impedance spectra were fitted well with the proposed equivalent circuit model. The analyses suggested that the thickness and the resistance of passive film on the surface of alloys increased with the increase of Pd content in the alloys. The results of XPS experiments demonstrated that the addition of Pd in the alloys suppressed the oxidation and enhanced the anti-corrosion capabilities of the alloys. When the Pd content reached 0.1, the corrosion resistant performances of Mg0.9-xTi0.1PdxNi（x=0.04～0.1） alloys are the best and the discharge capacity retention rate is the highest.