Nanocrystalline titanium-type metal hydride electrodes prepared by mechanical alloying

摘要

Mechanical alloying (MA) was employed to produce nanocrystalline TiFe_(1-x)Ni_x alloys (x=0, 0.25, 0.5, 0.75 and 1.0). XRD analysis showed that, after 25h of milling, the starting mixture of the elements had decomposed into an amorphous phase. Following annealing in high purity argon at 750 deg C for 0.5h, XRD confirmed the formation of the CsCl-type structures with crystallite sizes of about 50 nm. These materials were used as negative electrodes for a Ni-MH_x battery. With increasing nickel content in TiFe_(1-x)Ni_x, the material shows an increase in discharge capacity which passes through a maximum for x=0.75. In the nanocrystalline TiFe_(0.25)Ni_(0.75) powder, discharge capacities of up to 155 mA h g~(-1) (at 40 mA g~(-1) discharge current) were measured. The titanium-based hydrogen storage alloys are attractive for secondary batteries, because of inexpensive raw materials.