Potassium silanide (KSiH3): a reversible hydrogen storage material

KSi silicide can absorb hydrogen to directly form the ternary KSiH₃ hydride. The full structure of α‐KSiD₃, which has been solved by using neutron powder diffraction (NPD), shows an unusually short Si? D lengths of 1.47 Å. Through a combination of density functional theory (DFT) calculations and experimental methods, the thermodynamic and structural properties of the KSi/α‐KSiH₃ system are determined. This system is able to store 4.3 wt % of hydrogen reversibly within a good P–T window; a 0.1 M Pa hydrogen equilibrium pressure can be obtained at around 414 K. The DFT calculations and the measurements of hydrogen equilibrium pressures at different temperatures give similar values for the dehydrogenation enthalpy (≈23 kJ mol^?1 H₂) and entropy (≈54 J K^?1 mol^?1 H₂). Owing to its relatively high hydrogen storage capacity and its good thermodynamic values, this KSi/α‐KSiH₃ system is a promising candidate for reversible hydrogen storage.