Combustion and Electrochemical Decomposition Performance of Hydroxylammonium Nitrate-Based Electrically Controlled Solid Propellant on Metal Electrodes

Hydroxylammonium nitrate-based electrically controlled solid propellant (HAN-ECSP) has garnered significant research interest due to its high energy density and at-will on–off capability. In this study, combustion tests revealed that the ignition delay time and mass combustion rate of the propellant vary depending on the electrode materials (Cu, Ni, Ti, and Ta). To investigate the underlying mechanisms behind these variations, electrochemical properties and decomposition performance were also achieved, which can also quickly evaluate and select electrodes in HAN-ECSP. Among these tested electrodes, Cu exhibited the best performance, with an ignition delay time of 0.77 s. Further electrochemical analysis showed that Cu electrodes provided the highest conductivity (4.05 S/m), lowest overpotential (1.10 V), and highest double-layer capacitance (2.79 × 10⁻⁴ F·m⁻²). Additionally, combustion tests revealed that the Cu electrode led to the highest gas pressures and the highest concentration of H₂ under all applied voltages. These findings suggest that Cu is the most suitable electrode material for HAN-ECSP. Moreover, the composition and concentration of major gases produced during the decomposition of propellant further elucidated its combustion behavior. The results indicate that the ignition delay time is strongly correlated with the concentration of H₂, while the combustion duration is influenced by the concentration of O₂. Overall, this study establishes a clear connection between the electrochemical and decomposition properties of HAN-ECSP and its combustion performance, offering valuable insights into electrode material selection.