复合储氢合金Mg_(1.8)Zr_(0.2)Ni-(1.2–X)Ni-XMgTi_3的结构和电化学性能

Structure and Electrochemical Properties of Composite Hydrogen Storage Alloy Mg_(1.8)Zr_(0.2)Ni-(1.2–X)Ni-XMgTi_3

为改善Mg_2Ni储氢合金的电化学性能,采用机械合金化法(mechanical alloying,MA),分别制备出改性合金Mg_(1.8)ZrNi以及MgTi_3,按一定比例和Ni混合球磨,制备出纳米晶或非晶化的Mg_(1.8)Zr_(0.2)Ni-(1.2–X)Ni-XMgTi_3(X=0.0~0.8)复合储氢合金。结果表明,经部分取代改性和包覆修饰后的复合储氢合金,其表面和内部形成较多的纳米级褶皱、空隙和多相结构缺陷。随着MgTi_3含量增加(X=0.0~0.5),Mg_(1.8)Zr_(0.2)Ni-(1.2–X)Ni-XMgTi_3复合储氢合金初始放电比容量也逐渐增加,当MgTi_3含量为X=0.5时,合金初始放电比容量为973.3 m Ah·g^(-1)。但MgTi_3含量X>0.5时,其初始放电比容量又有所下降。研究表明,添加MgTi_3却不利于复合储氢合金的循环稳定性和高倍率放电性能。通过对Mg_(1.8)Zr_(0.2)Ni-(1.2–X)Ni-XMgTi_3复合储氢合金进行线性极化、阳极极化和交流阻抗测试,进一步研究了系列合金电极的表面电化学反应、电荷转移过程、氢在合金中的扩散情况以及它们的电化学性能。

In order to improve the electrochemical properties of hydrogen storage alloy Mg2Ni, modified alloys Mg1.8Zr0.2Ni-（1.2–X）Ni-XMgTi3 were prepared by mechanical alloying, and then mixed and ball milled with Ni in a certain proportion to prepare an amorphous modified alloy Mg1.8Zr0.2Ni-（1.2–X）Ni-XMgTi3（X=0.0-0.8）. The results show that there are a large number of nanoscale folds, voids and multiphase structural defects on the surface and inside of the composite hydrogen storage alloys after partial substitution modification and coating modification. With the increase of MgTi3 content（X=0.0-0.5）, the initial discharge specific capacity of Mg1.8Zr0.2Ni-（1.2–X）Ni-XMgTi3 gradually increases. When the content of MgTi3 is 0.5, the initial discharge specific capacity is 973.3 m Ah·g-1, but when the content of MgTi3 is greater than 0.5, the initial discharge specific capacity rapidly decreases. The results indicate that the addition of MgTi3 is not beneficial to the cycle stability and high rate discharge performance of the composite hydrogen storage alloy. By testing the linear polarization, anodic polarization and electrochemical impedance spectra of Mg1.8Zr0.2Ni-（1.2–X）Ni-XMgTi3, the surface electrochemical reaction, charge transfer process, hydrogen diffusion in the alloy and the electrochemical performance of modified alloys were further investigated.