| 摘要 |
PURPOSE:To increase capacity and to prolong service life by controlled-cooling a hydrogen occluding alloy for a rare earth type Ni-hydrogen battery having a specific composition from a molten state to solidify it and then performing annealing in specific conditions. CONSTITUTION:The hydrogen occluding alloy for Ni-hydrogen battery has a composition represented by formula LmaabNicCodMneAlf. In formula, Lm means mixed rare earth metals containing >70wt.% La, A is at least one among Zr Mo and 0.97<=a<=1.02, 0.01<=b<=.04, 0.98<=a+b<=1.03, c>=3.5, 0.50<=d<=0.90, 0.50<=e<=0.40, 0.20<=f<=0.60, and c+d+e+f=5.0 are satisfied. The alloy having this composition is melt-refined and solidified from molten state at >=500 deg.C/sec cooling rate. Subsequently, annealing is done in vacuum or in an inert gaseous atmosphere at 600-900 deg.C for 2-5hr. By this method, the hydrogen occluding alloy having high capacity (>=300mAh/g) and long service life (capable of holding a capacity >=80% the initial capacity at 300 cycles) can be obtained. |
