Hygroscopicity of Ammonium‐Based Energetic Ionic Salts: Mechanisms and Mitigation Strategies

ABSTRACT

Ammonium‐based energetic salts, including ammonium dinitramide (ADN), ammonium perchlorate (AP), and ammonium nitrate (AN), are promising candidates for next‐generation high‐energy materials due to their high energy density and environmentally benign decomposition. However, their severe hygroscopicity limits practical application, leading to energy degradation, increased sensitivity, and compromised storage stability. This review elucidates the multiscale mechanisms governing the moisture uptake of these salts, bridging molecular interactions and crystallographic properties. We emphasize the synergistic effects of polar functional groups and crystal defects, which facilitate strong hydrogen bonding and capillary condensation. Furthermore, we demonstrate that ion type, impurity content, and environmental fluctuations dictate the critical relative humidity (RH). To mitigate hygroscopicity, we systematically discuss a tripartite optimization strategy encompassing molecular design, crystal engineering, and interfacial modification. We highlight recent technological advances, including the incorporation of sterically hindered ions, cocrystallization, spherical crystallization, and core–shell encapsulation. Additionally, we evaluate the integration of computational modeling and machine learning (ML) as pathways for accelerated predictive design and process optimization. Finally, this work identifies existing research gaps and provides theoretical insights to guide the development of safe, high‐performance, and moisture‐resistant energetic materials.