Pramod D. Mhase, Ram A. Pawar, Varsha C. Pujari, Paresh S. More, Gaurav Singh, Darshna Potphode, Mehboobali Pannipara, Abdullah G. Al‐Sehemi, Sunil M. Patange
ABSTRACT A novel M‐type barium–strontium hexaferrite, Ba 0.5 Sr 0.5 Fe 12 O 19 , was synthesized via a sol–gel auto‐combustion route and evaluated as a supercapacitor electrode material. X‐ray diffraction confirmed the formation of a single‐phase hexagonal magnetoplumbite structure with nanoscale crystallinity, supported by FTIR and Raman analyses. XPS results revealed mixed Fe 2+ /Fe 3+ valence states and oxygen vacancies, enhancing redox activity. Optical studies indicated a direct band gap of 2.15 eV, favorable for charge storage. BET analysis showed a mesoporous structure with a surface area of 5.37 m 2 /g and an average pore diameter of 37.77 nm, promoting efficient ion diffusion. Electrochemical measurements in 3 M KOH demonstrated pronounced pseudocapacitive behavior, delivering a specific capacitance of 206 F/g at 5 mV/s and retaining 70% at 100 mV/s. The electrode exhibited excellent cycling stability, maintaining nearly 100% capacitance after 4000 cycles. Nyquist analysis revealed low solution resistance ( R s = 0.488 Ω) and charge‐transfer resistance ( R ct = 0.625 Ω), indicating efficient charge transport. These results highlight Ba 0.5 Sr 0.5 Fe 12 O 19 as a promising and cost‐effective electrode material for advanced supercapacitor applications.