The thermal decomposition of ammonium perchlorate and HTPB-CSP combustion is promoted by the “litchi” core-shell structure of MnCo2O4.5

This study systematically investigates the relationship between the solvent used, the crystal morphology of MnCo₂O_4.5, and its thermocatalytic activity using the solvent thermal method. By tweaking the urea content in the solvothermal process and the ethanol/glycol ratio in the reaction solvents, the shape and size of the MnCo₂O_4.5 precursor were controlled by altering the crystal growth direction and rate. The MnCo₂O_4.5 material with “litchi” core-shell structure with maximum specific surface area and abundant pore structure is prepared when the addition amount of urea is 27 mmol and the solvent is ethanol/glycol (20:40 mL). This material reduces the high thermal decomposition temperature (T_HTD) of ammonium perchlorate (AP) from 473.48 °C to 274.86 °C and increases the exothermic amount from 888.26 J g⁻¹ to 1654.03 J g⁻¹. Compared to pure AP (296.8 kJ mol⁻¹), the activation energy (E_a) of AP + 2.0 wt% MnCo₂O_4.5 catalytic material decreases to 61.1 kJ mol⁻¹. Applying the “litchi” core-shell structured MnCo₂O_4.5 to the hydroxyl-terminated polybutadiene composite solid propellant (HTPB-CSP) enhances combustion intensity, reducing the time to peak combustion from 390 ms for pure AP to 265 ms and ignition delay from 35 ms to 21 ms. The experimental results indicate that the “litchi” MnCo₂O_4.5 boosts AP thermal decomposition and improves HTPB-CSP combustion.