Crystal Structure and Electrochemical Properties of AB3.8-Type Earth Mg Ni-Based Hydrogen Storage Alloys
La0.8-xPrxMg0.2Ni3.8 (x=0,0.15,0.3,0.4) alloys were prepared by induction melting followed by annealing treatment at 1173K for 24 h. Alloys structure and electrochemical properties of different Pr elecment have been studied systematically by X-ray diffraction(XRD) with the Rietveld methold , scanning electron microscope (SEM)and electrochemical experiments. Alloys structure analyses show that all of the alloys mainly consisted of complex phases such as (La,Pr,Mg)5Ni19 phase(Ce5Co19-type,SG:R-3m), (La,Pr,Mg)5Ni19 phase (Pr5Co19-type, SG:P63/mmc)and (La,Pr)Ni5 phase(CaCu5-type,SG:P6/mmm), Pr eletment was benefited to the formation of Pr5Co19-type phase, The (La,Pr,Mg)5Ni19 phase not only exists in high temperature area but also exists in low temperature area.The activation characteristic and maximum discharge capacity got worse with increasing Pr content,At the same time, The Pr5Co19–type phase and Ce5Co19–type phase all had better electrochemical cyclic stability than the PuNi3-type phase in earth–Mg–Ni-based Hydrogen Storage Alloys.The cyclic stability of alloy electrodes was a closely related to the stacking structures consisting of one Laves-type slab (AB2) and three CaCu5-type slabs (AB5) along the c-axis.
Jingtao Han, Zhengyi Jiang and Sihai Jiao
A. Q. Deng et al., "Crystal Structure and Electrochemical Properties of AB3.8-Type Earth Mg Ni-Based Hydrogen Storage Alloys", Advanced Materials Research, Vols. 156-157, pp. 108-112, 2011