Electrochemical properties of Ti_45-xZr _30+xNi₂₅ (x = -4, 0, 4) quasicrystal and amorphous electrodes produced by mechanical alloying

The effect of substitution of Zr for Ti on the discharge performance of electrodes consisted of Ti_45-xZr_{30+ x}Ni₂₅ (x = -4, 0, 4) powders produced by mechanical alloying (MA) and subsequent annealing was investigated by a three-electrode cell at room temperature. All the powders after MA were amorphous, but a subsequent annealing caused the formation of the icosahedral (i) quasicrystal phase with a Ti₂Ni type crystal phase as the second phase. The discharge capacities for both the amorphous and the i-phase electrodes decreased with increasing amount of Zr substituted for Ti. The maximum discharge capacity achieved was about 130 mA h/g from a (Ti₄₉Zr₂₆Ni ₂₅) i-phase electrode at the first discharge process. The discharge capacities of the amorphous electrodes were lower than those of the i-phase ones if the composition levels were alike.