First principles study of the destabilization of Li amide-imide reaction for hydrogen storage

The theoretical capacity for the combination of both reactions is 10.2 wt.%. The first reaction is, however, highly exothermic with a reaction enthalpy of nearly −145 kJ/mol H2, and thus requires very high temperatures for hydrogen release. This reaction thus cannot be used for reversible hydrogen storage. With the second reaction alone, the weight percent capacity drops to 6.4 wt.%. This is much lower but still remains acceptable. The reaction enthalpy of reaction (2) has been estimated to be −80 kJ/mol H2. This is still high and requires relatively high temperatures for hydrogen release. We present in this paper the results of ab initio electronic structure calculations, and show that this reaction enthalpy can be lowered significantly by the substitution of Cu or Ni at the site of Li, the substitution by Ni being more effective.