First-principles study of intrinsic defects, dopants and dopant-defect complexes in LiBH4

A first-principles study was reported based on density functional theory of hydrogen vacancy, metal dopants, metal dopant-vacancy complex in LiBH4, a promising material for hydrogen storage. The formation of H vacancy and metal doping in LiBH4 is difficult, and their concentrations are low. The presence of one kind of defect is helpful to the formation of other kind of defect. Based on the analysis of electronic structure, the improvement of the dehydrogenating kinetics of LiBH4 by metal catalysts is due to the weaker bonding of B—H and the new metal-like system, which makes H atom diffuse easily; H vacancy accounts for a trace amount of BH3 release during the decomposing process of LiBH4; metal dopant weakens the strength of B—H bonds, which reduces the dehydriding temperature of LiBH4. The roles of metal and vacancy in the metal dopant-vacancy complex can be added in LiBH4 system.