Theoretical modeling of experimental isotherms for hydrogen storage in La0.9Ce0.1Ni5 alloy

Abstract

This research reports the results of an experimental and numerical analysis of the La_0.9Ce_0.1Ni₅ alloy's hydrogen absorption and desorption isotherms at three distinct temperatures (T = 313 K, 333 K, and 353 K). We first determined the morphological and structural properties, as well as the hydrogen storage isotherms, of the intermetallic La_0.9Ce_0.1Ni₅ experimentally. The experimental isotherms were then compared to a mathematical model based on statistical physical theory. Due to the good agreement between the experimental isotherms and the proposed model, the insertion and release of hydrogen atoms (n_α, n_β), geometric densities of receptor sites (N_αm, N_βm), and absorption-desorption energies (P_α, P_β) were determined. Moreover, thermodynamic functions like enthalpy, entropy, Gibbs free energy, and internal energy were calculated using these parameters. The findings demonstrated that the intermetallic compound's CaCu₅ structure promotes the formation of stable metal hydrides through attractive interactions, ensuring that hydrogen atoms are securely trapped in the metal lattice, thereby enhancing the material's hydrogen storage capacity.