Photo courtesy of James Courtney Effect of halide additives on the hydrogen desorption of lithium amide. Rosalind Davies Hydrogen and Fuel Cells Doctoral Training Centre University of Birmingham, UK H2FC SUPERGEN Researcher Conference, 16th December 2014
[email protected] Outline □ Introduction and Background □ Amide Iodides □ Amide Bromides □ Amide Chlorides □ Amide Fluorides □ Conclusions Introduction to the LiNH2 system This stage requires high temperatures for reversibility Li3N + 2H2 Li2NH + LiH + H2 LiNH2 + 2LiH This stage alone has a gravimetric storage 1 capacity of 6.5 wt.% H2 1Chen, P., et.al., Nature, 2002, 420, 6193 Reaction of lithium halides with LiNH2 forms amide halides LiNH2 + LiCl + LiI + LiBr 3 3 5 Li4(NH2)3Cl Li7(NH2)6Br Li3(NH2)2I 4 Li2NH2Br 3Anderson, P., A., A., et. al., Faraday Discussions, 2011, 151 4Barlage, H., and Jacobs, H., Z. Anorg. Allg. Chem., 1994, 620, 479. 5Matsuo, M., et al., Chem. Mater., 2010, 22, 2702. Adding halides lowers the desorption temperature Lithium amide halide + LiH Temperature programmed desorption Suppression of ammonia release Formation of lithium imide halides, and systems can be rehydrogenated Anderson, P., A., et. al., Faraday Discussions, 2011, 151 Gravimetric effects Adding halides is gravimetrically unfavourable: Li (NH ) Cl 4 2 3 Li7(NH2)6Br Li (NH ) I 3 2 2 this work investigates the lower halide doping limits. Reaction of LiI with 3 LiNH2 12 hours at 150°C 5 Li3(NH2)2I Double-layered hexagonal structure a = 7.09109(5) Å, c= 11.50958(10) Å 5Matsuo, M., et al., Chem. Mater.,