In Situ Generation and Stabilization of Multiple Catalysts by Introducing a Graphene-Supported FeF2/FeOX Additive for Enhancing the Hydrogen Storage of LiBH4

LiBH4 has attracted significant interest due to its high-hydrogen storage capacity (18.5 wt % H2). However, its practical application is severely impeded by the high dehydrogenation temperature, sluggish hydrogen release kinetics, and poor reversibility. In this work, a graphene-supported rodlike FeF2/FeOX additive (FeF2/FeOX@G) is prepared and introduced into LiHB4 by a simple ball-milling. With an optimized LiBH4-to-FeF2/FeOX@G weight ratio of 7:3, the 7LiBH4-3(FeF2/FeOX@G) system starts dehydrogenation at a low temperature of 100 °C below and 8.7 wt % H2 is released upon heating to 400 °C, while 1.1 wt % H2 is released for pristine LiBH4. Moreover, the system releases rapidly 7.0 wt % H2 at 350 °C within 80 min, and a dehydrogenation capacity of 5.5 wt % is reached after 10 reversible hydrogen absorption and desorption cycles. The in situ formed FeB, Li3BO3, and Fe2B during the first dehydrogenation process acted as a synergistic catalysis, effectively improving the reversible hydrogen storage of LiBH4. This work provides insights into the design of unique additives to introduce multiple catalyst synergies to enhance the hydrogen storage performance of LiBH4.