Study on dehydrogenation properties of LiAlH₄ by doping NiTiO₃

Aim at the problem of LiAlH₄ exist excessive hydrogen release temperature and slow hydrogen release kinetics as hydrogen storage material, a modification method that preparing NiTiO₃ and doping it into LiAlH₄through mechanical ball milling was proposed. The effect of NiTiO₃ on dehydrogenation properties of LiAlH₄ were studied by temperature programmed desorption and isothermal desorption experiments, and the results show that the initial hydrogen release temperature of the LiAlH₄ doped with w(NiTiO₃)=6% decreases to 73 ℃, reduced by 120 ℃ compared to pristine LiAlH₄; in isothermal hydrogen release test, the LiAlH₄ of doping 6% NiTiO₃ at 180 ℃ can release w(H₂)=4.70% in 60 min, pristine LiAlH₄ hardly release hydrogen under the same conditions. The results show activation energy of dehydrogenation of w(NiTiO₃)=6% LiAlH₄ decreases to 71.56 kJ/mol for the first step and 122.49 kJ/mol for the second step, indicating for improving the kinetic performance of hydrogen release. Through XRD analysis, ball milling process destroy stability of NiTiO₃ and make it amorphization, while amorphous NiTiO₃ can provide active sites and increase hydrogen diffusion channels for dehydrogenation reaction of LiAlH₄. The experimental results show that the modification method doping NiTiO₃ effectively improve dehydrogenation properties of LiAlH₄.