Ultra-high reversible hydrogen storage capacity of Li₃N by graphene wrapping

Li3N was a promising hydrogen storage material due to its extremely high hydrogen storage capacity. However, the poor kinetic properties as well as the cycling performance further limited its commercial application. Herein, graphene interface-enhanced Li3N (Li3N-Gra) was prepared by rolling transfer of microspheres. The onset dehydrogenation temperature of Li3N-8 wt.%Gra was as low as 211°C without any metal-based catalyst, which is 58°C lower than that of blank Li3N. About 4.14 wt.% H2 was released by Li3N-8 wt.% Gra at 300°C within 10 min. Specially, Li3N-8 wt.%Gra has been demonstrated to release 4.12 wt.% H2 at 300°C even after 40 cycles with 98.0% capacity retention. The drastically reduced Li3N particle size, elevated defect concentration, and abundant graphene interfaces together contributed to the improved Li3N-Gra kinetic performance. The stable and abundant graphene interfaces served as structural supports and spatial barriers, which effectively improved the cycling stability of Li3N. The method proposed in this work for obtaining graphene interface-enhanced Li3N by microsphere rolling transfer was expected to be applied to various hydrogen storage materials to improve their hydrogen storage properties.