Effect of LiCe(BH4)3Cl with a high Li ion conductivity on the hydrogen storage properties of Li-Mg-N-H system

The effect of LiCe(BH4)(3)Cl on the hydrogen storage properties of Mg(NH2)(2)-2LiH system was studied systematically, which has a high Li ion conductivity. The hydrogen desorption temperatures for Li-Mg-N-H system shift to lower temperatures by 0.05LiCe(BH4)(3)Cl doping with the onset temperature of dehydrogenation decreasing by 40 degrees C and the peak temperature decreasing by 30 degrees C. The Mg(NH2)(2)-2LiH-0.03LiCe(BH4)(3)Cl composite exhibits an improved comprehensive hydrogen storage properties, which can reversibly store about 5.0 wt% hydrogen at 160 degrees C, and released hydrogen as much as 8.6 times faster than that of the Mg(NH2)(2)-2LiH composite at 160 degrees C. The results indicated that the LiCe(BH4)(3)Cl-containing sample exhibited much better cycling properties than that of Mg(NH2)(2)-2LiH sample. XRD and FTIR results show that the structure of LiCe(BH4)(3)Cl does not change before and after hydrogen absorption/desorption, indicating it plays the catalytic effect. The hydrogen desorption activation energy of Mg(NH2)(2)-2LiH doped with 0.03LiCe(BH4)(3)Cl was reduced by 37.5%. The rate-controlling step of desorption shifted from the diffusion to the chemical reaction by the addition of LiCe(BH4)(3)Cl, indicating that the diffusion rates of small ions like H+, Li+ and Mg2+ in Li-Mg-N-H system are significantly enhanced, which could be well explained by the improved ionic conductivity of LiCe(BH4)(3)Cl doped sample. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.