MnCo2O4@Co(OH)2-g-C3N4 preparation of composite materials and their performance in supercapacitors.

High performance electrochemical energy storage device is an important means to solve the energy problem. As one of the next generation energy storage components, supercapacitor has received more and more attention in recent years. In this work, we synthesized a self-supporting MnCo₂O₄@Co(OH)₂ core–shell heterostructure (CSHs), this can not only enhance the strength of the material, but also generate abundant electron transport pathways. In addition, we also added flaky carbon nitride (g-C₃N₄) after treatment with nitric acid (HNO₃) to improve the cycle stability and specific capacitance of the material. By adjusting the chemical bath (CBD) time, the loading amount of Co(OH)₂ nanosheets can be controlled, giving full play to the synergy between the materials, so that the prepared composite has greater specific capacitance, higher rate performance and better cycle stability. When the current density is 0.5 A·g⁻¹, the specific capacitance of the composite is about 1932 F·g⁻¹. In the two electrode system, the energy density is 23.2 Wh·kg⁻¹ at a power density of 600 W·kg⁻¹. At a high current density of 10 A·g⁻¹, after 10,000 cycles, the initial capacitance of the composite material maintained 83.3%. [ABSTRACT FROM AUTHOR]