Structure and electrochemical performances of Mg20−xYxNi10 (x = 0–4) alloys prepared by mechanical milling

Abstract

Mg2Ni-type Mg20−xYxNi10 (x = 0, 1, 2, 3 and 4) electrode alloys were fabricated by vacuum induction melting. Subsequently, the as-cast alloys were mechanically milled on a planetary-type ball mill. The effects of milling time and Y content on the microstructures and electrochemical performances of the alloys were investigated in detail. The results show that nanocrystalline and amorphous structure can be successfully obtained through mechanical milling. The substitution of Y for Mg facilitates the glass forming of the Mg2Ni-type alloy and significantly enhances the electrochemical characteristics of the alloy electrodes. Moreover, the discharge capacity of Y-free alloy monotonously grows with the milling time prolonging, while that of the Y-substituted alloys has the maximum values in the same case. The milling time of obtaining the greatest discharge capacity markedly decreases with Y content increasing. The electrochemical kinetics of the alloys, including high rate discharge ability (HRD), diffusion coefficient (D), limiting current density (IL) and charge transfer rate, monotonously increase with milling time extending.