Mechanical and electronic properties of perovskite hydrides LiCaH$$_{\mathrm {{3}}}$$ and NaCaH$$_{\mathrm {{3}}}$$ for hydrogen storage applications

Abstract

New methods and materials for storing hydrogen efficiently and safely have been studied intensively recently since hydrogen is being a great energy carrier for future green energy usage. One of these material groups is lightweight perovskite hydrides. The current study deals with LiCaH3 and NaCaH3 perovskite hydrides with regards to structural, elastic, electronic, mechanical stability, and hydrogen storage properties. All computations have been done using first principles calculations. Both perovskite hydrides are found to be mechanically stable and ductile in nature. Electronic band structures of hydrides depict indirect band gaps for both perovskite hydrides, indicating that they are non-metallic. LiCaH3 and NaCaH3 have band gaps as 2.37 eV and 2.23 eV, respectively. The gravimetric hydrogen density of LiCaH3 is found to be 5.7 wt% and 4.38 wt% for NaCaH3which are reasonable in line with the goal that is set by US Energy Department which is 4.5 wt%.