Mg2Ni alloy for metal hydride electrodes

A study was made of the effects of ball-milling Mg2Ni alloy with nickel powder, and chemically coating it with nickel on the alloy properties. Three types of alloys, nickel mixed, nickel ball-milled and nickel coated Mg2Ni alloy, were used as the active material of metal hydride electrodes. The ball-milling of the alloy with nickel powder results in an amorphous or nanocrystaline phase. Chemical coating of the alloy with nickel was carried out at 25 degrees C. The alloy particles were pulverised by the colliding process during the ball-milling and possibly by a hydrogen decrepitation mechanism during the coating process. Electrochemical measurements show that the electrode fabricated from the nickel mixed Mg2Ni alloy was very difficult to charge and discharge at room temperature, while the characteristics of the electrode prepared by nickel ball-milling or nickel coating were greatly improved because of the changed phase structure and surface behaviour. (C) 1998 Kluwer Academic Publishers.