Abstract

Mg2Ni has drawn attention due to its high reaction rates, good reversibility, and possibility to be applied as a negative electrode in the Ni-MH (metal hydride) batteries. Mg2Ni samples were prepared by sintering under Ar in a stainless-steel crucible at 823K. Johnson-Mehl equation for nucleation and growth mechanism was applied to the behaviors of hydriding and dehydriding reactions of Mg2Ni. At 571K under 30bar H2, the activation of the Mg2Ni sample was completed at the number of cycles of three (n=3). At n=3, hydrided fractions of the sample were 0.51 (1.92wt% H) at 0.50min and 0.90 (3.38wt% H) at 2.00min. Reverse temperature dependences of the initial hydriding rate and the quantity of hydrogen absorbed for 60min appeared from 571K to 620K. Hydriding and dehydriding reactions progressed by the nucleation and growth mechanism and could be expressed by the Johnson-Mehl equation.

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