Potassium Silanide (KSiH 3 ): A Reversible Hydrogen Storage Material

KSi silicide can absorb hydrogen to directly form the ternary KSiH 3 hydride. The full structure of α‐KSiD 3 , which has been solved by using neutron powder diffraction (NPD), shows an unusually short SiD 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‐KSiH 3 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 H 2 ) and entropy (≈54 J K −1  mol −1 H 2 ). Owing to its relatively high hydrogen storage capacity and its good thermodynamic values, this KSi/α‐KSiH 3 system is a promising candidate for reversible hydrogen storage.