Phase Structure and Electrochemical Properties of the AB3.8-Type La-Mg-Ni

Abstract:

The phase structure and electrochemical properties of La0.8-xPrxMg0.2Ni3.8 and La0.8-xPrxMg0.2Ni3.2Al0.2Co0.4 (x=0, 0.15, 0.3, 0.4) hydrogen storage alloys were investigated systematically. The structure analyses show that the alloys are mainly composed of multiphases, such as Pr5Co19 phase, Ce5Co19 phase and CaCu5 phase. The increase of Pr content in the alloys leads to an increase of the A5B19 (Pr5Co19 +Ce5Co19)-type phases; at the same time, both the lattice parameters (a, c) and the cell volume (v) for all phases are also decreased. Al element addition favors the formation of CaCu5-type phase. The electrochemical test indicates that the A5B19-type phase alloy has good electrochemical cycle stability, and the Al and Co elements can improve the electrochemical cycle stability of A5B19-type phase alloys

Key words:hydrogen storage alloy; phase structure; electrochemical properties