The Sieverts data for hydrogen desorption by (LiNH2+2LiH)@(6-nm PC) (Figure , right) show that it releases hydrogen much faster than the bulk material. The mechanism of hydrogen desorption by nanoconfined (LiNH2+2LiH) has been investigated using a porous carbon host with 3-nm pores. The phase fraction calculations informed from the energetics predicted by DFT calculations indicate that internal nanoscale phase boundaries influence the thermodynamics, leading to a single-step reaction in which the intermediate imide phase (Li2NH) is destabilized. The reaction is fully reversible, showing that nanoconfinement can alter the reaction pathway, in this case avoiding the hydrogen-trapping imide intermediate. The higher loading we achieved for (LiNH2+2LiH)@(6-nm PC) increases the capacity to 5.4 wt%. Arrhenius parameters for H2 desorption required for system modeling were obtained by fitting to Equation (1) (Fig. , Table , and Table ). The activation energy for hydrogen release from (LiNH2+2LiH)@(6-nm PC) is 139 kJ/molH2, (the activation energy for the 3-nm material was not reported by Wood et al. ), which interestingly is similar to the value Pinkerton reported for pure bulk LiNH2. However, compared with the bulk material the preexponential factor (A) for (LiNH2+2LiH)@(6-nm PC)