A high-performance hydrogen generation system: Hydrolysis of LiBH4-based materials catalyzed by transition metal chlorides

Lithium borohydride (LiBH 4 ) has received much attention due to its high hydrogen density of 18.5 wt%. However, in the hydrolytic process for hydrogen supply, the sluggish kinetics of LiBH 4 and the agglomeration of by-product greatly limit its wide utilization. In this work, transition-metal chlorides (CoCl 2 , NiCl 2 , FeCl 3 ) are firstly adopted to explore the hydrogen liberation behaviors of LiBH 4 . The hydrolysis kinetics can be well-controlled by tuning the concentration of chlorides. Among the above chlorides, CoCl 2 displays much faster reaction kinetics, delivering a hydrogen generation rate ranging from 421 to 41701 mL min −1 g −1 with a maximum conversion of 95.3%, much higher than the value of 225 mL min −1 g −1 H 2 with Pt–LiCoO 2 . The maximum gravimetric hydrogen density may reach 8.7 wt% at H 2 O/LiBH 4  = 2–6 mol/mol. Furthermore, NH 3 is introduced to solve the issue of uncontrollable kinetics of LiBH 4 by forming its ammoniates, where LiBH 4 ·NH 3 catalyzed by CoCl 2 could stably release over 4350 mL g −1 H 2 per unit weight of LiBH 4 within 30 min at 40 °C, with a hydrogen density of ∼7.1 wt% and a hydrogen yield of 97.0%. Our approaches adopting non-noble metal chlorides are efficient and affordable for hydrogen supply to PEMFCs via hydrolysis of LiBH 4 -based materials.