Electrochemical properties of Ti45−xZr30+xNi25 (x=−4, 0, 4) quasicrystal and amorphous electrodes produced by mechanical alloying

Abstract

• All the Ti 45−x Zr 30+x Ni 25 powders ( x = −4 to 4) after mechanical alloying were amorphous. • Subsequent annealing formed the icosahedral quasicrystal phase with a Ti 2 Ni phase. • The maximum discharge capacity was about 90 mA h/g for (Ti 49 Zr 26 Ni 25 ) amorphous. • The maximum discharge capacity was about 130 mA h/g for (Ti 49 Zr 26 Ni 25 ) quasicrystal. • The amorphous partially converted to a hydride, but the quasicrystal remained stable. The effect of substitution of Zr for Ti on the discharge performance of electrodes consisted of Ti 45− x Zr 30+ x Ni 25 ( 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 Ti 2 Ni 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 (Ti 49 Zr 26 Ni 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.