Effects of Quenching Rate on Microstructure and Electrochemical Properties of (Mg_70.6Ni_29.4)₉₂La₈ Alloys

摘要

Amorphous and nanocrystalline (Mg70.6Ni29.4)92La8 alloys were prepared by rapid solidification. Themicrostructure of the as-quenched ribbons and the electrochemical properties of these alloys withdifferent velocity of cooling roll were characterized and measured. The experimental results showedthat the degree of short-range order and the discharge-capacity increased with increasing velocity of cooling roll for (Mg70.6Ni29.4)92La8 alloys. The highest discharge capacity reached 568.5 mAh g for-1 (Mg70.6Ni29.4)92La8 sample with the velocity of 21.8ms . It capacity conservation rate was 79.3%after 10 cycles. It is obvious that Mg2NiH4 phase forms during the charging process. The amorphousbackground concealed by the strong Nipeaks shows much amorphous phase remains. It indicated thatthe amorphous structure was a key factor to achieve high discharge capacity and good cycling stability.