Preparation and electrochemical hydrogen storage properties of MWCNTs-doped Ti49Zr26Ni25 alloy containing quasicrystal phase

Abstract Mechanical alloying technique and subsequent annealing were used to prepare the Ti 49 Zr 26 Ni 25 quasicrystal. Composite materials of multi-walled carbon nanotubes (MWCNTs) doped Ti 49 Zr 26 Ni 25 alloys were obtained via ball-milling to improve the hydrogen storage performance of Ti 49 Zr 26 Ni 25 . X-ray diffraction, scanning electron microscopy and transmission electron microscopy were used to analyze the structural properties of the samples. The phase structures of the composite alloys were composed of icosahedral quasicrystal phase and Ti 2 Ni-type phase. Smaller alloy particles were obtained after doping MWCNTs. Moreover, a three-electrode battery system was carried out to test the electrochemical properties. The composites showed higher discharge capacity, stronger HRD, better cyclic stability and lower charge-transfer resistance than the original Ti 49 Zr 26 Ni 25 alloy. In the composite electrodes, the optimal discharge capacity of 254.2 mAh/g and the highest capacity retention of 63.1% were achieved for 5 wt.% additive content of MWCNTs. The electro-catalytic function of MWCNTs, the reduction of particle size and raise of specific surface area for Ti 49 Zr 26 Ni 25 alloy may provide larger electrochemically accessible area and rapid channel for hydrogen transportation, which are crucial for improving the electrochemical performance of the alloy.