Ball mill assisted synthesis of cobalt–iron sulfide/N-doped carbon for high performance asymmetric supercapacitors

• Published in: Journal of applied electrochemistry 2020-11, Vol.50 (11), p.1119-1128
• Main Authors: Karuppannan, Mohanraju, Kim, Youngkwang, Lee, Dohyeon, Sung, Yung-Eun, Kwon, Oh Joong
• Format: Article
• Language: English
• Subjects: Activated carbon; Asymmetry; Ball milling; Capacitance; Capacitors; Carbon; Chemistry; Chemistry and Materials Science; Cobalt; Electrochemical analysis; Electrochemistry; Electrode materials; Electrodes; Electron microscopy; Energy storage; Flux density; Industrial Chemistry/Chemical Engineering; Iron; Iron sulfides; Metal foams; Microscopy; Nickel; Photoelectrons; Physical Chemistry; Raman spectroscopy; Research Article; Spectrum analysis; Sulfides; Supercapacitors; Synthesis; X ray photoelectron spectroscopy
• ISSN: 0021-891X; 1572-8838
• DOI: 10.1007/s10800-020-01466-5

Cobalt–iron sulfides supported on N-doped carbon were synthesized as energy storage material using ball milling followed by carbonization. As-synthesized materials were structurally analyzed by X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy. Furthermore, cobalt–iron sulfides supported on N-doped carbon were coated on Ni foam, and their electrochemical performance was tested in a 3-M KOH electrolyte. The as-fabricated Co–Fe–S-2 electrode registered a specific capacitance of 1252 F g −1 at 1 A g −1 and also showed capacitance retention of 66.4% at 20 A g −1 . In addition, asymmetric supercapacitors (ASC) were fabricated using the as-synthesized electrode materials and it had a voltage window of 0 – 1.6 V. Among them, the activated carbon (AC)//Co–Fe–S-2 ASC device showed maximum specific capacitance of 169.3 F g −1 at 1 A g −1 , and it registered maximum energy density of 59.6 Wh kg −1 at power density of 0.796 kW kg −1 . The AC//Co–Fe–S-2 device delivered a rate capability of 55.6% at 30 A g −1 , and it reveals a capacitance retention of 76.3% over 5000 cycles. Herein we also found that ball-milling-assisted synthesis of Co–Fe–S-2 electrode material is a promising candidate for high-performance ASCs. Graphic abstract