Structure and electrochemical properties of (La1−xDyx)0.8Mg0.2Ni3.4Al0.1 (x = 0.0–0.20) hydrogen storage alloys

Abstract The structure and electrochemical characteristics of (La 1− x Dy x ) 0.8 Mg 0.2 Ni 3.4 Al 0.1 ( x  = 0–0.20) hydrogen storage alloys have been investigated. Dysprosium was adopted as a partial substitution element for lanthanum in order to improve electrochemical properties. The XRD, SEM and EDX results showed that the alloys were composed of (La, Mg) 2 Ni 7 , LaNi 5 and (La, Mg)Ni 2 phases. The introduction of Dy promoted the formation of (La, Mg) 2 Ni 7 phase which possesses high hydrogen storage capacity, and controlling dysprosium content at 0.05 can obtain the maximum (La, Mg) 2 Ni 7 phase abundance in the alloys. The maximum discharge capacity was heightened from 382.5 to 390.2 mAh/g, which was ascribed to (La, Mg) 2 Ni 7 phase abundance increasing from 54.8% to a maximum (60.5%). Also, the biggest discharge capacity retention remained 82.7% after 100 cycles at discharge current density of 300 mA/g.