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.