In-situ fabrication of polyaniline-strontium hexaferrite composites for efficient electrodes in symmetric supercapacitor

In this study, we report the development of a novel nanocomposite comprised of hexagonal disc-shaped strontium hexaferrite (SHF) and polyaniline (PANI) for supercapacitor application. SHF powders are synthesized via a hydrothermal method, and PANI/SHF composites with varying ratios are prepared through in situ polymerization. Microstructural studies confirm the formation of M-type SHF (SrFe₁₂O₁₉) phase with hexagonal disc morphology. The electrochemical performance of PANI/SHF composites with varying compositions is demonstrated in a symmetric two-electrode cell configuration. The specific capacitance of the electrode is enhanced significantly for PANI/SHF composites compared to pristine SHF and PANI. The optimum value of specific capacitance ~ 505 F/g is observed for the electrode with composite having 1:1 SHF-to-PANI ratio at a scan rate of 2 mV/s. The device also demonstrates an energy density of 17.56 Wh/kg and a power density of 126.45 W/kg, along with excellent cycling stability, retaining 83.6% capacitance after 8,000 cycles. The effect of PANI content on enhancing SHF's supercapacitor properties through efficient charge carrier dynamics is systematically investigated. The improved performance is attributed to the synergistic effect of PANI's high conductivity and SHF’s electrochemical stability, highlighting their promise for next-generation supercapacitor electrodes.