Facile Synthesis and Thermal Stability Enhancement of Sulfurized Polyacrylonitrile for Thermal Battery Cathodes

Although sulfide-polyacrylonitrile (SPAN) is considered a promising cathode material for various battery applications, their application in thermal batteries has not yet been explored. Herein we synthesized carbonized SPAN (c-SPAN) to enhance the thermal stability of SPAN and evaluated its application as a cathode for thermal batteries. The efficiency of c-SPAN materials was demonstrated by comprehensive structural analysis and thermal stability evaluation, including scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman, and thermogravimetric analysis (TGA). The c-SPAN exhibited significantly improved thermal stability compared to conventional PAN, which was attributed to the stable structure resulting from the chemical bonding of sulfur to the PAN-derived turbostratic carbon matrix. In addition, the bond dissociation energy of the C–S bond (272 kJ/mol) was higher than that of the S–S bond (251 kJ/mol), further contributing to the enhanced thermal stability. The thermal stability of c-SPAN was considerably affected by the mixing method and thermal treatments conditions, and maintained stability up to 500°C under optimal conditions. Additionally, a thermal battery incorporating c-SPAN was successfully operated, indicating that the c-SPAN material developed in this study is a viable candidate for thermal battery applications. These results suggest it is one of the promising cathode materials for various thermal battery applications.