The study on the electrochemical performance of mechanically alloyed Mg–Ti–Ni-based ternary and quaternary hydrogen storage electrode alloys

In this paper, ternary Mg50−xTixNi50 (x=5,10,15) and quaternary Mg35Ti10M5Ni50 (M=Y,Al,Zr) magnesium-based hydrogen storage electrodes prepared by means of mechanical alloying (MA) were investigated. Through X-ray diffractometer (XRD) and scanning electron microscope (SEM) investigation, the phase structure transformation and morphology of Mg35Ti15Ni50 during MA process were examined. The effects of Ti content on discharge capacity, the cycling life and high rate dischargeability of the ternary Mg–Ti–Ni electrode alloys were studied in the discharge tests. It was found that as the Ti content increased the cycling stability of Mg50−xTixNi50 alloys improved but the discharge capacity and high rate discharge-ability both decreased. The MA quaternary Mg35Ti10M5Ni50 (M=Y,Al,Zr) alloys had significantly longer cycling life but lower discharge capacity than the ternary alloy Mg35Ti15Ni50. Surface coating of alloy particles with Ni was also tested for improving the cycling stability of the ternary alloys and found beneficial for cycling stability and bad for discharge capacity