Role of Rare-Earth Alloys in Lithium Borohydride Regeneration from Hydrous Lithium Metaborate

Lithium borohydride (LiBH4) is a promising hydrogen storage material, but the irreversibility of hydrolysis and the high cost of regeneration have severely restrained its commercial applications. Herein, we reported a cost-effective method to regenerate LiBH4 by ball milling hydrous lithium metaborate (LiBO2·2H2O) with low-cost Mg-based alloys, instead of MgH2, under ambient conditions. An effective strategy is developed to improve the regeneration kinetics of LiBH4 by introducing the light rare-earth metals into Mg to facilitate the breakage of B–O and conversion of H+ into H–. A yield of 40% can be achieved for a relatively short ball milling duration (10 h) for the LiBO2·2H2O-CeMg12 system. The optimized regeneration of LiBH4 is believed to be efficient and economical since it utilizes an intrinsic hydrogen source in LiBO2·2H2O and cheap reducing agents. Our finding is expected to enable a wide deployment of LiBH4 for hydrogen storage.