Nanocomposite Electrode Materials Prepared from Pinus roxburghii and Hematite for Application in Supercapacitors

Abstract

Wood-based nanocomposite electrode materials were synthesized for application in supercapacitors by mixing nanostructured hematite (Fe2O3) with highly porous activated carbon (AC) produced from the wood-waste of Pinus roxburghii. The AC was characterized using various instrumental techniques and the results showed admirable electrochemical properties, such as high surface area and reasonable porosity. Firstly, AC was tested as an electrode material for supercapacitors and it showed a specific capacitance of 59.02 Fg–1 at a current density of 1 Ag–1, cycle life of 84.2% after 1,000 cycles (at a current density of 3 Ag–1), and energy density of 5.1 Wh/kg at a power density of 135 Wkg–1. However, when the AC was composited with different ratios of Fe2O3 (1:1, 2:1, and 1:2), there was an overall improvement in its electrochemical performance. Among the 3 ratios, 2:1 (AC:Fe2O3) had the best specific capacitance of 102.42 Fg–1 at 1 Ag–1, cycle life of 94.4% capacitance after 1,000 cycles (at a current density of 3 Ag–1), and energy density of 8.34 Wh/kg at a power density of 395.15 Wkg–1 in 6 M KOH electrolyte in a 3-electrode experimental setup with a high working voltage of 1.55 V. Furthermore, when Fe2O3 was doubled, 1:2 (AC:Fe2O3), the electrochemical capacitive performance of the electrode twisted and deteriorated due to either the accumulation of Fe2O3 particles within the composite or higher bulk resistance value of pure Fe2O3.