Mg-Fe-Ni非晶储氢电极材料的微结构和电化学性能

采用XRD、SEM、电化学测试等方法研究了机械球磨合成的Mg-Fe-Ni非晶储氢电极材料的微结构和电化学储氢性能. 结果表明, 镁含量和镍粉添加量对复合物的电化学性能有显著影响. 对于(xMg+Fe)+200% (质量分数, 余同)Ni (x=2、3) 复合物, 随Mg含量增加, 最大放电容量增大. 当x=2、3时复合物的最大放电容量分别为391.9、480.8 mA•h•g^-1. 无镍的(3Mg+Fe)复合物最大放电容量仅为23.8 mA•h•g^-1；对于(3Mg+Fe)+y% Ni (y=0、50、100、200), 随着镍添加量的增加, 球磨120 h合成复合物的最大放电容量先增加后减小,并在y=100时达到最高值519.5 mA•h•g^-1. 微结构分析表明,无镍的Mg-Fe复合物经120 h球磨后仍为Mg和Fe两个单相混合组织, 无新相产生, 而加入镍粉有助于Mg-Fe非晶相的形成, Ni还起到良好的表面电催化作用, 改善了非晶Mg-Fe-Ni复合物的电化学性能.

Microstructure and Electrochemical Properties of Amorphous Mg-Fe-Ni Hydrogen Storage Electrode Material

The amorphous Mg-Fe-Ni composites have been synthesized by mechanical ball-milling. The microstructure and electrochemical properties of the composites were characterized by XRD, SEM and electrochemical testing. The electrochemical properties of the composites vary greatly with the amount of Mg content and Ni introduced. For the (xMg+Fe)+200% (mass fraction) Ni (x=2, 3) composites, it is found that the maximal discharge capacity increases with increasing Mg content in the composites. The maximal discharge capacities of the composites with x=2, 3 were 391.9 mA•h•g^-1 and 480.8 mA•h•g^-1, respectively. The result also indicates that, for the ball-milled (3Mg+Fe)+y% Ni (y=50, 100, 200) composites, with increasing Ni content in the composites, the discharge capacity increases first and then decreases, and reaches a maximum value of 519.5 mA•h•g^-1 as y=100. In contrast, the discharge capacity of nickel-free (3Mg+Fe) composite is just 23.8 mA•h•g^-1. The microstructure analysis shows that the composites are mix structure composed two single phases with Mg and Fe for the nickel-free composite even after being milled for 120 h, but no new phase is formed. The composites milled with the addition of nickel powder could easily form Mg-Fe amorphous structure. Besides, the nickel powder in the composites plays a role of electro-catalysis, hereby the electrochemical properties of the Mg-Fe-Ni composites are effectively improved.