Effects of N₂ mixed gas atomization on electrochemical properties of Mm(Ni,Co,Mn,Al)_5.0 alloy powder

N₂ gas, N₂-Ar mixed gas and Ar gas atomization followed by acid surface treatment was applied to improve electrochemical properties of AB₅ type hydrogen storage alloy powder. The shape of Ar atomized powder was spherical and it changed to be irregular with increasing N₂ content of mixed gas. Irrespective of gas kinds, electrodes of atomized powder showed the same discharge capacity as cast-pulverized powder under auxiliary electrical conductivity by nickel powder addition. Without nickel powder, however, N₂ atomized powder showed the best electrochemical properties as well as gas activation behavior. By the combination process of N₂ gas atomization and acid surface treatment, it was considered that irregular shape of N₂ atomized powder promoted electrical conductivity of electrodes and catalytic nickel concentrated surface layer was formed to increase the hydrogen storage rapidity.