Improved electrochemical hydrogen storage capacity of Ti45Zr38Ni17 quasicrystal by addition of ZrH2

Abstract

Ti45Zr38Ni17+xZrH2 (x=5, 10, 15 and 20wt%) composite materials are produced by ball milling for 20min. The results of XRD measurement show that the composite materials contain icosahedral quasicrystal phase (I-phase), FCC phase with a Ti2Ni type crystal and C14 Laves phase. After adding ZrH2, the composite materials include not only the individual phases mentioned above, but also the ZrH phase. These composite materials are used as the negative electrode material of the nickel-metal hydride batteries. The electrochemical hydrogen storage characteristics of the material after adding ZrH is investigated. The Ti45Zr38Ni17+xZrH2 (x=5, 10, 15 and 20wt%) composite material has reached the maximum discharge capacity (83.2mAh/g) when x equals 10. This maximum discharge capacity is much higher than that of Ti45Zr38Ni17 alloy without ZrH. After adding ZrH2, the high-rate discharge ability and the cycling stability are enhanced simultaneously. The improvement of the electrochemical properties can be attributed to the synergistic effects of ZrH2, and the synergistic effects in the composite electrodes are probably attributed to the entry of most of hydrogen atoms from weakly bond strength of the Zr-H to the I-phase structure in electrochemical reaction.