Hydrogen sorption kinetics and suppression of NH3 emission of LiH-sandwiched LiNH2-LiH-TiF4-MWCNTs pellets upon cycling.

NH 3 emission during decomposition of LiNH 2 -LiH composite reduces hydrogen storage capacity and poisons fuel cell catalysts. The idea of sandwiching LiNH 2 -LiH pellet with LiH layers (10–30 wt%), reacting with NH 3 and transforming into H 2 is proposed. The LiH-sandwiched LiNH 2 -LiH pellets show no sign of NH 3 release with the hydrogen capacitates of 3.5–4.0 wt% H 2 during the 1st cycle. Upon cycling (the 2nd-6th cycles), decomposition of LiH-sandwiched LiNH 2 -LiH pellet with the low amount of LiH layer (10 wt%) shows NH 3 signal, while that with 30 wt% LiH layers liberates only hydrogen with the storage capacities of 2.3–2.6 wt% H 2. Effective dehydrogenation and reversibility of the 30 wt% LiH-sandwiched LiNH 2 -LiH pellet are explained by not only sufficient content and mechanical stability of LiH layers but also the formation of the new active phases (LiH 1−x F x and Li 2 NH 1−y F y). • New idea of sandwiching LiNH 2 -LiH composite with LiH layers. • Excellent suppression of NH 3 release upon de/rehydrogenation cycles. • Significantly improved de/rehydrogenation kinetics and reversible H 2 capacities. • Detailed reaction mechanisms upon hydrogen exchange reaction. • Formation of new catalytic and reversible phases of LiH 1-x F x and Li 2 NH 1-y F y. [ABSTRACT FROM AUTHOR]