Ti2Ni alloy: a potential candidate for hydrogen storage in nickel/metal hydride secondary batteries

An amorphous Ti2Ni alloy, prepared by mechanical milling of a crystalline Ti2Ni alloy, was heat-treated at several temperatures. The crystalline behavior of the amorphous alloy was studied, relative to a multi-stage crystallization mode, using X-ray diffraction, differential scanning calorimetry, and electron diffraction. X-Ray photoelectron spectroscopy was performed to analyze the surface structure of the alloys. The alloy that was heat-treated at 693 K, with a non-equilibrium bulk structure and a protective surface layer, has a high discharge capacity and good cycling stability. The issue of severe capacity loss of Ti2Ni-based alloys, which has caused problems for many years, has been significantly improved.