Characteristic of a new Mg-Ni hydrogen storage system: Mg2-xNi1-yTixMny (0< x < 1, 0 < y < 1) alloys

Mg-based hydrogen storage alloys Mg2-xNi1-yTixMny (0 <x <1, 0 <y <1) have b een successfully synthesized using a diffusion method (DM). The structure o f these alloys has been examined by X-ray diffraction. A new phase was foun d in the alloys. Multi-Rietveld analysis showed that the new phase has a cu bic crystal structure and its chemical formula is A,BC,, in which A stands for Mg, C stands for Ni and B stands for some microstructure of Ti and Mn. Further studies reveal that the new phase has excellent gas-solid reaction properties and electrochemical capacities. In the solid-gas reaction the de sorption capacity of the alloy was about 355.26 ml H-2 (S.T.P) g(-1) alloy. Its discharge capacity also reached values as high as 335.8 mAh g(-1) (50 mA g(-1), -0.5 V vs. Hg/HgO electrode). Some possible reasons for the excel lent performances have been suggested. (C) 2001 Elsevier Science B.V. All r ights reserved.