Abstract

Thermochemical ammonia sorption offers high heat‐storage density and low cyclic heat loss over long periods, making it a promising new approach for building heating. The sorption/desorption behavior of the sorbent material underpins the performance of a sorption heat‐storage cycle, and the material's intrinsic properties have a profound impact on system output. Previous studies have demonstrated that ternary composite sorbents can significantly enhance the conversion ratio of reactive salts toward NH<inf>3</inf> sorption. However, the underlying promotion mechanism at the electronic‐structure level has not yet been elucidated. In this work, density functional theory was employed to optimize the molecular configurations of the ternary composite sorbent, and wavefunction‐based analyses were used to investigate its electronic‐level sorption behavior. The results reveal that the sorption kinetics of SrCl<inf>2</inf> with NH<inf>3</inf> are governed by a nucleophilic–electrophilic reaction. The incorporation of ENG and carbon-coated nanometals modifies the sorbent's wavefunction, thereby reshaping its surface electrostatic potential and enhancing sorption kinetics. Thermodynamic calculations coupled with atomic localization analyses indicate that for the ternary composite sorbent, the adsorption kinetics are significantly improved while the overall heat-storage density of the system does not decrease. This study provides a mechanistic explanation of how ternary composite sorbents promote NH<inf>3</inf> sorption at the microscopic level, offering valuable guidance for the practical, large-scale application of ammonia–based sorption heat‐storage systems.