Influence of Fe₃O₄ nanoparticles on pseudocapacitive behavior of the charge storage process

Nano-crystalline Fe₃O₄ powders were added to form manganese oxide/iron oxide composite film electrode in order to combine the excellent capacitance characteristics of manganese oxide and iron oxide. Due to the addition of Fe₃O₄, the crack film formation increases the contact area of electrolyte and electrode and the surface and electronic conductivity of pseudo-capacitors increased. The specific capacitance value can be enhanced by adding iron oxide. The surface of the composite film with Fe₃O₄ added had small holes due to the burnout of organics, and the network of nano-powders formed uniform and fine pores at 300 °C annealing. The EXAFS results to the XRD results, the peaks shift due to the formation of Mn₃O₄ and Mn₂O₃ between 250 and 350 °C. The best results in this study were 316.1 F/g obtained at 1 at.% of manganese oxide/iron oxide composite film electrode after 300 °C annealing. The 1 at.% manganese oxide/iron oxide composite film electrode after 1000 cycles, the highest specific capacitance value was 85.8%. The results showed that manganese oxide/iron oxide composite film electrode have good cycle stability of capacitance.