Supercapacitive properties of spray pyrolyzed iron-added manganese oxide powders deposited by electrophoretic deposition technique

Nanocrystalline iron-added manganese oxide powders were prepared by spray pyrolysis (SP) from manganese acetate and iron nitrate solutions at 400 °C. The as-obtained powders were subsequently deposited onto graphite substrates via an electrophoretic deposition technique (EPD). The as-prepared powders were examined by transmission electron microscopy (TEM) and X-ray diffractometry (XRD); the electrochemical properties of the coatings were further examined by cycling voltammetry (CV). Structural investigation by TEM and XRD revealed that the as-deposited coatings exhibited Mn₃O₄ phase with nanocrystalline structure. CV examinations showed that the iron addition significantly improved the electrochemical properties of the Mn-oxide powder coatings. The specific capacitance of as-deposited Mn-oxide coating was increased from 202 F/g to 232 F/g when 2 at.% of iron was added. Even after 1200 cycles of life test, the iron-added coatings exhibited higher cycling efficiency (~ 78% of the initial maximum capacitance) than that unadded one (~ 60% of its maximum value).