Reactive destabilization and bidirectional catalyzation for reversible hydrogen storage of LiBH4 by novel waxberry-like nano-additive assembled from ultrafine Fe3O4 particles

•A novel waxberry-like Fe3O4 (w-Fe3O4) is developed as multifunctional additive.•The w-Fe3O4 strongly destabilized LiBH4, leading to dehydrogenation below 100 °C.•In situ formed FeB/Fe2B as catalytic nucleation sites for (de)hydrogenation of LiBH4.•A capacity retention of 70% is achieved after 10 cycles for LiBH4 with 30wt% w-Fe3O4.•The bidirectional catalytic mechanism of FeB/Fe2B as e− transfer medium is revealed.