Thermodynamic Modeling of the Ni–H System

A new
thermodynamic assessment of the Ni–H system has been
carried out, providing a complete description valid up to 6 ×
109 Pa of this system at the center of hydrogen storage
issues. The study includes the hydride formation reaction and the
presence of a miscibility gap in the fcc interstitial solid solution
of hydrogen in nickel. In addition to a complete literature review,
first-principles calculations were carried out and combined with other
modeling approaches. The cluster expansion method allowed us to describe
the energetic interactions between atoms leading to the miscibility
gap in the fcc solid solution. Besides, the compressibility at high
pressure was characterized for each phase including the condensed
phases. For this purpose, a specific high-pressure model was assessed
with the contribution of quasi-harmonic phonon calculations. The obtained
consistent model allows us to characterize entirely the thermochemical
behavior of the Ni–H system.