First-principles studies of K₁ _− _xM_xMgH₃ (M = Li, Na, Rb, or Cs) perovskite hydrides for hydrogen storage

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<P><B>Abstract</B></P> <P>The structural stability and hydrogen release properties of M-doped KMgH<SUB>3</SUB> (M = Li, Na, Rb, or Cs) were examined using density functional theory (DFT) calculations. The reaction enthalpies (ΔH) of the four possible dehydrogenation reaction pathways were calculated using the doped structures with different phases ( P m 3 ¯ m , P<I>nma</I>, and R3<I>c</I>). The most favorable reaction pathway among these four pathways was found. Among the dopants investigated, the most promising dopant for this reaction was Li. In addition, the application of pressure was found to be useful for tuning the reaction enthalpies of the dehydrogenation reactions. Overall, the results present an efficient means of designing new promising perovskite-type hydrides for hydrogen storage.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Perovskite-type KMgH<SUB>3</SUB> is a promising candidate for hydrogen storage. </LI> <LI> The most favorable reaction pathway of dehydrogenation reactions was examined. </LI> <LI> Li was the most useful and effective dopant to release hydrogen. </LI> <LI> Pressure can be usefully employed for tuning the reaction enthalpies of dehydrogenation reactions. </LI> </UL> </P>