Efficient hydrogen generation from noncatalytic alcoholysis of Al/LiBH 4 mixture for fuel cell applications

Aluminum (Al) and lithium borohydride (LiBH 4, LB for short) are highly promising candidates for chemical hydrogen storage. However, the direct utilization of Al–H 2 O reaction faces significant challenges due to the inherent issue of surface passivation, which prevents the ongoing reaction between Al and H 2 O. Additionally, the hydrolysis of LB is constrained to temperatures exceeding 0 °C, and the development of cost-effective catalysts that enable efficient hydrogen release from LB hydrolysis remains a bottleneck in realizing its practical application. Herein, we present an efficient noncatalytic hydrogen generation system utilizing Al and LB mixtures, enabling H 2 production over a broad temperature range using methanol, ethanol, or their mixtures as reaction solvents. Our results demonstrate that the H 2 generation kinetics of Al-LB composites can be precisely tailored by adjusting various parameters, such as LB content, ball-milling time, reaction temperature, and solution composition. In comparison with the traditional Al and its alloy systems, Al-LB composites exhibit remarkable performance in both hydrogen capacity and H 2 kinetics. For instance, the Al-50 % LB composite achieves a hydrogen yield of 2322 mL g −1 H 2 within 5 min (∼80 % fuel conversion). Specifically, with a 70 % LB content, the composite generates over 3100 mL g −1 H 2 within the same time, realizing nearly 90 % fuel conversion. Notably, the apparent activation energy of the Al-30 % LB and Al-50 % LB composites is determined to be 29.1 kJ mol −1 and 13.9 kJ mol −1, much lower than that of Al-based hydrolyzable materials. These findings hold significant importance for the advancement of practical Al-based hydrogen generation systems designed for mobile or portable applications.