Revealing the Effect of Solvents on Morphology Control of Lithium Pentazolate Salt

ABSTRACT

Lithium pentazolate (LiN ₅ ) is a novel nitrogen‐rich energetic material that exhibits excellent detonation properties. However, it is difficult to control its crystal morphology after precipitating from a single solvent. Herein, various crystal morphologies were obtained by adjusting the solvents (NMP, DMA, DMF, and EtOH) and antisolvents (DCM, EA) combination. In contrast to the raw material with a cubic morphology, the LiN ₅ crystals derived from DMA‐EA adopt a rod‐like morphology, while the EtOH‐EA and EtOH‐DCM yield tetragonal block‐like and quasi‐ellipsoidal morphologies, respectively. Both cubic and tetragonal block‐like crystals show higher thermal stability (159°C–161°C) than that of rod‐like and quasi‐ellipsoidal counterparts (148°C–150°C). The impact sensitivity (IS) of quasi‐ellipsoidal crystals (IS = 25 J) is superior to that of rod‐like (IS = 8 J) and tetragonal block‐like (IS = 15 J) morphology. Unfortunately, the desired quasi‐ellipsoidal crystals exhibit slightly higher hygroscopicity with a water content of 7.8% under the same conditions. Moreover, XRD analysis shows that the EtOH solvent leads to a significantly enhanced diffraction peak corresponding to the (430) plane of LiN ₅ , whereas the EA antisolvent results in an additional distinct peak assigned to the (432) plane. Our results propose a general strategy for regulating the crystal morphology of LiN ₅ , further revealing the connection between crystal morphology and physical–chemical properties.