Synthesis of the carbon-optimized integrated cobalt-based electrode for high cycle performance supercapacitors

Co ₃O ₄ and nickel–cobalt layered double hydroxide (Ni-Co LDH) have been extensively studied as a typical cobalt-based pseudocapacitive materials. To further improve their electrochemical performance, the cobalt-based materials and carbon were integrated to prepare hierarchical Co ₃O ₄ @C@Ni-Co LDH nanoarrays through the hydrothermal and calcination methods. According to the characterization, the results show the Co ₃O ₄ nanocones with single-crystalline structure serve as the stable frameworks and the amorphous carbon coated on the Co ₃O ₄ nanocones improves the conductivity and the structural stability significantly. Moreover, numerous active sites of Redox reactions, provided by the Ni-Co LDH, improve specific capacitance of electrode. Based on performance measurements, it was illustrated that the integrated Co ₃O ₄ @C@Ni-Co LDH electrodes possessed the outstanding performance of specific capacitance (1755 F/g at 1 A/g) with remarkable cycling stability (specific capacitance remained at 90.47% after 5000 cycles at the current density of 10 A/g) because of the synergetic effects of high activity and conductivity Co ₃O ₄ @C scaffolds and well-defined Ni-Co LDH nanoneedles. The asymmetric supercapacitors, based on Co ₃O ₄ @C@Ni-Co LDH // active carbon, showed an extraordinary cyclic stability with the retention rate of specific capacitance is 94.47% after 16000 cycles. Furthermore, prepared devices showed the excellent energy density with 33.02 Wh/kg with the power density was 398.85 W/kg. The excellent electrochemical properties of Co ₃O ₄ @C@Ni-Co LDH electrodes indicate that the multi-component integrated materials have great theoretical significance for the study of high-performance electrode materials, and also reflect that the Co ₃O ₄ @C@Ni-Co LDH electrodes exhibit outstanding value and extremely promising prospect in practical application.