Synthesis and Electrode Characteristics of Mg(2-x)AlxNi Alloys by Combustion Synthesis

Abstract

The Mg-based hydrogen storage alloy Mg 2- x Al x Ni( x =0.1-0.5) was synthesized by combustion synthesis. XRD indicates that a new phase with the cubic Ti 2 Ni structure appears in the product, and SEM shows that there are a large number of defects on the alloy surface. The effect of partial substitution of Al for Mg on the electrochemical performances of Mg 2 Ni was investigated. The results show that Al addition affects its electrode characteristics strongly. The electrochemical capacity and cycle lives of Al-containing alloys increase strongly compared to the Al-free alloy. This is attributed to the structure of a new phase (Mg 3 AlNi 2 ), and the formation of the protect layer of Al 2 O 3 . In addition, the results reveal that mechanical grinding is beneficial to improve activation behavior and the maximum electrode capacity, but can not improve the cyclic stability due to breaking of Al 2 O 3 protect layer.