Sulphur-doped Co3O4 nanowires as an advanced negative electrode for high-energy asymmetric supercapacitors

Abstract

Negative electrode materials with high capacitance performance are highly desired for asymmetric supercapacitors (ASCs). In this work, a novel kind of sulphur-doped Co₃O₄ (S-Co₃O₄) negative electrode material with enhanced electrochemical properties was developed by doping sulphur into Co₃O₄. The S-Co₃O₄ nanowires grown on carbon cloth by a hydrothermal method achieved an areal capacitance of 0.55 F cm⁻² at 10 mV s⁻¹ in a 5 M LiCl solution, which is more than 11 times that of the untreated Co₃O₄ electrode. Moreover, the S-Co₃O₄ electrode has an excellent long-term cycling stability with more than 92% capacitance retention after 10 000 cycles. In addition, a high-performance flexible supercapacitor (ASC) was also prepared with S-Co₃O₄ nanowires as a negative electrode and MnO₂ as a positive electrode. A maximum energy density of 0.86 mW h cm⁻³ and a maximum power density of 0.79 W cm⁻³ were achieved for the as-fabricated ASC device.