Pulsed laser deposited CoFe ₂O ₄ thin films as supercapacitor electrodes

Abstract

The influence of the substrate temperature on pulsed laser deposited (PLD) CoFe ₂O ₄ thin films for supercapacitor electrodes was thoroughly investigated. X-ray diffractometry and Raman spectroscopic analyses confirmed the formation of CoFe ₂O ₄ phase for films deposited at a substrate temperature of 450 °C. Topography and surface smoothness was measured using atomic force microscopy. We observed that the films deposited at room temperature showed improved electrochemical performance and supercapacitive properties compared to those of films deposited at 450 °C. Specific capacitances of about 777.4 F g ⁻¹ and 258.5 F g ⁻¹ were obtained for electrodes deposited at RT and 450 °C, respectively, at 0.5 mA cm ⁻² current density. The CoFe ₂O ₄ films deposited at room temperature exhibited an excellent power density (3277 W kg ⁻¹) and energy density (17 W h kg ⁻¹). Using electrochemical impedance spectroscopy, the series resistance and charge transfer resistance were found to be 1.1 Ω and 1.5 Ω, respectively. The cyclic stability was increased up to 125% after 1500 cycles due to the increasing electroactive surface of CoFe ₂O ₄ along with the fast electron and ion transport at the surface.

Abstract

Cobalt ferrite thin films were grown by PLD at different temperatures as an electrode material for supercapacitors. The films deposited at room temperature exhibited the best power density (3277 W kg ⁻¹) and energy density (17 W h kg ⁻¹) values.