International Journal of Energy Research, Vol.45, No.2, 2882-2898, 2021
Improved hydrogen storage performances ofLiAlH(4)+ Mg(BH4)(2)composite withTiF(3)addition
This paper studies on the preparation of the alanate-borohydride combined system, LiAlH4 + Mg(BH4)(2)with diverse molar ratios (1:1, 1:2, and 2:1) using the ball milling technique. The findings show that there is a mutual destabilization between the hydrides where the newly combined system has superior hydrogen storage performances as opposed to the unary components (LiAlH(4)and Mg[BH4](2)). Analysis on the initial decomposition temperature and isothermal de/hydrogenation kinetics has proven that the 2LiAlH(4) + Mg(BH4)(2)system possesses better performance. In an endeavor to ameliorate the performances of the hydrogen storage of 2LiAlH(4) + Mg(BH4)(2), the destabilized system was doped with TiF3. Three major steps of desorption were detected during the heating process in the 2LiAlH(4) + Mg(BH4)(2)system with and without the addition of TiF3, which are correlated to the decomposition of Mg(AlH4)(2), MgH(2)and LiBH4. It is found that 2LiAlH(4) + Mg(BH4)(2) + 5 wt.% TiF(3)has decreased the initial decomposition temperature at about 60 degrees C, which is 55 degrees C lower than the non-catalyzed 2LiAlH(4) + Mg(BH4)(2)system. The isothermal absorption/desorption kinetics of the 2LiAlH(4) + Mg(BH4)(2)system have also been enhanced by the addition of TiF3. The activation energy for Mg(AlH4)(2)-, MgH2-, and LiBH4-relevant decomposition after doped 2LiAlH(4) + Mg(BH4)(2)with TiF(3)are reduced to 36.5, 23.3, and 17.6 kJ mol(-1). Studies on the structural characteristics analysis of the 2LiAlH(4) + Mg(BH4)(2) + TiF(3)sample hint to the fact that the formation of the MgF2, LiF, TiH(2)and Ti-Al species, during desorption, is the main responsible factor for the observed thermodynamics change of the reactions by modifying the dehydrogenation and hydrogenation pathway. The catalytic role played by TiF(3)may have encouraged the interaction between Mg(AlH4)(2), MgH2, and LiBH4, further ameliorate the de/hydrogenation of the 2LiAlH(4) + Mg(BH4)(2) + TiF(3)destabilized system.