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

Abstract

Co3O4 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 Co3O4 @C@Ni-Co LDH nanoarrays through the hydrothermal and calcination methods. According to the characterization, the results show the Co3O4 nanocones with single-crystalline structure serve as the stable frameworks and the amorphous carbon coated on the Co3O4 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 Co3O4 @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 Co3O4 @C scaffolds and well-defined Ni-Co LDH nanoneedles. The asymmetric supercapacitors, based on Co3O4 @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 Co3O4 @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 Co3O4 @C@Ni-Co LDH electrodes exhibit outstanding value and extremely promising prospect in practical application.