An AB₂X₅-type oxidizer by multi-ionic assembly for high-energy solid propellants

Solid propellants are a crucial power source for modern aerospace, whose energy enhancement primarily relies on breakthroughs in oxidizer performance. However, the key energy parameters of oxidizers are interdependent. Improvements in oxygen balance and enthalpy of formation lead to a decrease in hydrogen content. Addressing this limitation, this study synthesized a novel AB₂X₅-type oxidizer, (CH₃NH₃⁺)(NH₃CH₂CH₂NH₃²⁺)₂(ClO₄⁻)₅ (named EMP), via a multi-ion assembly strategy. EMP achieves synergistic optimization of oxygen balance (OB_CO: 11%), enthalpy of formation (−187.5 kJ·mol⁻¹), and hydrogen content (4.01%), while also being characterized by simple synthesis, high density (1.859 g·cm⁻³), high decomposition temperature (330.7 °C), and low hygroscopicity (critical humidity: 78% RH at 25 °C). Theoretical predictions indicate that in HTPB-based solid propellants, EMP as an oxidizer can increase the theoretical specific impulse to 279.9 s, significantly outperforming ammonium perchlorate (AP, 263.7 s). The experiment further confirmed that partially replacing AP by EMP (around 20 wt%) in traditional AP-based propellants can enhance the burning rate (from 4.68 to 5.31 mm·s⁻¹) and effectively reduce the average molecular weight of combustion products, demonstrating the enhanced energy release efficiency and energy conversion efficiency of the propellant. This work not only validates the application potential of EMP as a high-performance oxidizer but also provides novel insights and experimental evidence for the molecular design and performance regulation of next-generation solid propellant oxidizers.