From biomass to energy storage materials: Mangosteen shells derived carbon doped Co3O4 as supercapacitor electrode materials

Cheese-like mangosteen shell derived activated carbon (MC) with high specific surface area and well-developed pore structure is prepared by one-step alkali activation method. Co₃O₄/MC composite is prepared by growing Co₃O₄ microspheres in MC pores via one-step hydrothermal method. Compared with individual Co₃O₄, Co₃O₄/MC composite exhibits excellent electrochemical property with the specific capacitance up to 324.4 F g⁻¹. The MC skeleton has increased the physical strength of the composite and significantly reduced the charge transfer resistance of Co₃O₄. The asymmetric supercapacitor device Co₃O₄/MC//MC exhibits high specific capacitance of 80 F g⁻¹ in the voltage window of 0∼1.6 V. Under the power density of 4000 W kg⁻¹, the energy density can be as high as 27 Wh kg⁻¹. After 10000 charge/discharge cycles, capacitance retention and coulombic efficiency are around 100%. The asymmetric supercapacitor device is used to light electronic meter and a red light-emitting diode, indicating the potential application in energy storage field.