Significantly improved de/rehydrogenation properties of lithium borohydride modified with hexagonal boron nitride

The remarkable hydrogen de/absorption properties of lithium borohydride are achieved by mechanically milling LiBH4 with hexagonal boron nitride (h-BN). It is found that the dehydrogenation properties of LiBH4 are improved with increasing the amount of h-BN. The 30 mol% h-BN doped LiBH4 composite starts to release hydrogen from just 180 degrees C, which is 100 degrees C lower than the onset dehydrogenation temperature of ball milled LiBH4. Moreover, the 30 mol% h-BN doped LiBH4 composite can release 12.6 wt% hydrogen in 2 h at 400 degrees C, while only 0.98 wt% H-2 is gained from ball milled LiBH4. The apparent activation energy (Ea) of hydrogen desorption had been reduced from 198.31 kJ mol(-1) for ball milled LiBH4 to 155.8 kJ mol(-1) for 30 mol% h-BN doped LiBH4. In addition, the rehydrogenation of the composite is achieved under 400 degrees C and 10 MPa of H-2. These remarkable results are largely attributed to the lone pair electrons of nitrogen induced destabilization of LiBH4 and their heterogeneous nucleation.