Verification and kinetics analysis on the synthesis of LiBH4 from LiH + MgB2

•The efficient and fast synthesis method of LiBH4 was presented.•The formation kinetics of LiBH4 from LiH-MgB2 is nucleation/growth controlled.•The formation of LiBH4 is may be heterogeneous nucleation and one-direction growth.

In the present work, the efficient and fast synthesis method of LiBH4 using LiH + MgB2 as starting material was experimentally verified. It was found that the conversion of LiH + MgB2 into LiBH4 + MgH2 was rapidly completed in ∼15 min under 7 MPa H2 at 673 K. Meanwhile, LiBH4 was successfully separated from MgH2 using MTBE (methyl tert-butyl ether) as solvent. Kinetics analysis results not only suggested that the rate limiting step during formation process of LiBH4 from LiH + MgB2 is nucleation/growth controlled but also indicated that the formation process of LiBH4 is probably controlled by heterogeneous nucleation and one-direction growth. Our kinetics analysis result provides a plausible explanation for the significantly kinetic enhancement of transition metal halides or oxides in the Li-Mg-B-H hydrogen storage system.