A novel all-nitrogen molecular crystal as promising high-energy density material

In the decades-long search for energy-dense materials capable of greater energy output, many studies have focused on nitrogen rich compounds, which have the advantages of relative stability at ambient conditions, high-energy output when broken down, and a clean gas product (N₂) that is inert, non-toxic, and a non-contributor to the greenhouse effect. The most stable form of nitrogen under ambient condition is N₂ molecular crystal, because of its exceedingly stable triple bond in nature. Besides N₂, there is not any report of other all nitrogen molecular crystals either at ambient condition or under high pressure, except a recently reported N₈ crystal. Here, using ab initio calculations combined with an intelligence structure-searching, we report the discovery of a thermodynamically stable nitrogen molecular crystal, which has perfect packing and more energetic stability at lower pressure range, compared with the N₈ crystal. While decompose at ambient pressure, this all nitrogen molecular crystal can release great amount of energy (~2.90 kJ/g).