Improved electrochemical hydrogen storage properties of Ti49Zr26Ni25 quasicrystal alloy by doping with Pd and MWCNTs

Abstract

Ti49Zr26Ni25 quasicrystal was fabricated via mechanical alloying and subsequent annealing. The mixtures containing different amounts of Pd and MWCNTs were doped into the Ti49Zr26Ni25 alloy by ball-milling method. The icosahedral quasicrystal and Ti2Ni-type phases were the main phase compositions for the composite alloys. The composite alloy combined the large specific surface area and high conductivity of MWCNTs in conjunction with the excellent electrocatalysis ability of Pd, thus improving the discharge capacity and cycle stability of the matrix alloy. The Ti49Zr26Ni25 + MWCNTs + Pd electrode possessed a maximum discharge capacity of 281.6 mAh/g, outstandingly higher than those for Ti49Zr26Ni25 (206.1 mAh/g), Ti49Zr26Ni25 + MWCNTs (248.4 mAh/g) and Ti49Zr26Ni25 + Pd (259.3 mAh/g). The cycle stability and high-rate dischargeability were also enhanced. Furthermore, the studies on electrochemical reaction kinetics demonstrated that doping of Pd and MWCNTs accelerated the charge-transfer process, the two active materials played synergistic effect in enhancing the electrochemical activity and reaction kinetics for the Ti49Zr26Ni25 electrode.