Enhanced hydrogen storage properties of 1.1MgH2–2LiNH2–0.1LiBH4 system with LaNi5-based alloy hydrides addition

摘要

Significant improvements in the hydrogen sorption properties of the Li–Mg–N–H system have been achieved by adding a small amount of LiBH _(4) . Herein, the hydrogen storage properties of the 1.1MgH _(2) –2LiNH _(2) –0.1LiBH _(4) system are further enhanced by addition of LaNi _(5) -based (LaNi _(3.8) Al _(0.75) Mn _(0.45) , LaNi _(4.5) Mn _(0.5) , LaNi _(4) Co) alloy hydrides. The refinement of the Li–Mg–B–N–H particles and the metathesis reaction are facilitated by adding LaNi _(5) -based alloy hydrides during the ball milling process. The addition of LaNi _(5) -based alloy hydrides can enhance the hydrogen sorption kinetics, reduce the dehydrogenation temperature and promote a more thorough dehydrogenation of the Li–Mg–B–N–H system. The LaNi _(5) -based alloy hydrides are involved in hydrogen de/hydrogenation reaction. Among the three alloys, LaNi _(4.5) Mn _(0.5) makes the most obvious improvement on the reaction kinetics, and the dehydrogenation peak temperature is reduced by 12 °C, while the activation energy is reduced by 11% with 10 wt% LaNi _(4.5) Mn _(0.5) addition. The weakening of the N–H bond and the homogeneous distribution of the LaNi _(5) -based alloy hydrides in the Li–Mg–B–N–H composite have important roles in the reduction of the desorption barrier and the kinetics enhancement.