N-doped carbon-assisted low-temperature sulfidation: a green strategy for constructing high-performance CoNi2S4/N-doped carbon electrode for supercapacitors
摘要
To construct high-performance CoNi2S4/nitrogen-doped carbon (NC) electrode material with well-retained porous structure, a NC-assisted low-temperature synthetic strategy was proposed here by using inorganic sodium sulfide as the sulfuric agent. The composed NC could not only promote the sulfidation of nickel-cobalt precursor by inhibiting the formation of byproducts under low temperature, but also elevate the overall conductivity of the final composite. Owing to its high sulfidation degree and well-preserved porous structure, the as-prepared CoNi2S4/NC could deliver high specific capacitances of 1580 F g− 1 at 1 A g− 1 and 1268 F g− 1 at 20 A g− 1, as well as remarkable cycling stability of 90.63% capacitance retention after 10,000 cycles. The asymmetric supercapacitor assembled from CoNi2S4/NC positive electrode and g-CN negative electrode could achieve high energy density of 59.68 Wh kg− 1 at 788.43 W kg− 1, and a high capacitance retention of 92.85% after 10,000 cycles. This work proposes an effective low-temperature hydrothermal strategy to synthesize CoNi2S4/NC composites electrode with well-maintained porous structure, high conductivity and remarkable redox activity, which enable its superior capacitive performance in supercapacitors.