Cyclo ‐N 9 − : a Novel 5/6 Fused Polynitrogen Anion for High Energy Density Materials (Adv. Sci. 19/2025)

Polynitrogen Anion In article number 2414394, Yuangang Xu, Ming Lu, and co‐workers present a novel 5/6 fused polynitrogen anion, cyclo ‐N 9 − , following the cyclo‐pentazolate anion. Four ionic systems derived from this framework exhibit exceptional energy density and detonation performance, surpassing even CL‐20, making them highly promising candidate energetic materials with significant research value. This research provides valuable theoretical insights into the advancement of polynitrogen species synthesis.