Design Of Ordered Mesoporous Carbon-based Composites And Study The Performances Of Asymmetric Supercapacitors

With the utilization of green and sustainable clean energy,it is particularly significant to develop a convenient and efficient energy storage and conversion device.At present,the main energy storage systems are batteries and supercapacitors.The latter has a greater operating temperature range,longer cycle life,better environmental friendliness,and higher power density than the former.However,supercapacitors suffer from lower energy density.In this research,novel carbon-based electrode materials are designed and prepared to enhance the specific capacity and energy density of supercapacitors.（1）The hierarchical ordered mesoporous carbon is designed for supercapacitor electrode.The synergistic effect of the mesoporous channels and the external cation（K⁺）framework endows SBA-C-K-N excellent electrochemical properties,such as good specific capacitance of 134.4 F g^-1 at 0.5 A g^-1,superior chemical stability（retain 97.3%of initial capacitance）.Comprehensive characterization analysis confirmed that the external cation（K⁺）frame can enhance specific capacitance and reduce impedance.（2）The ordered mesoporous carbon decorated with nano-flowers assembled by Ni Co S nano-sheets is achieved by a facile oil method and hydrothermal sulfuration.The OH^-in host layers and CO₃^2-guest ions of Ni Co Al LDH precursor are replaced by S^2-during the sulfuration etching,resulting in the destruction of the lamellar structure.Meanwhile,the element Al is difficult to form stable sulfide and dissolve in solution.NiCoS@SBA-C electrode shows good electrochemical performances,such as superior specific capacitance of 1757 Fg^-1 at 1 Ag^-1,excellent rate capacity(maintain 79.68%of origin capacitance at 20 Ag^-1).The asymmetric supercapacitor assembled by NiCoS@SBA-C and SBA-C electrodes delivers the energy density of 38.8 Wh kg^-1 at800 Wkg^-1 and demonstrates remarkable electrochemical stability(retain 97.8%after5000 cycles at 5 A g^-1).（3）The ultrathin MnO₂ nano-sheets are grown on the surface of SBA-C through a self-limit redox reaction between KMnO₄ solution and carbon.Subsequently,Fe OOH nano-needles are derived from MnO₂ by substitution reaction between Fe and Mn.Both MnO₂@SBA-C and Fe OOH@SBA-C electrodes show good specific capacitance of219.7 and 240.6 Fg^-1 at 1 and 2 Ag^-1,respectively.The asymmetric supercapacitor assembled by MnO₂@SBA-C and FeOOH@SBA-C electrodes elivers the energy density of 39.4 and 14.2 Wh kg^-1 at the power density of 500 and 8000 W kg^-1,respectively.Based on the above research,we can actually enhance comprehensive electrochemical performances of the asymmetric supercapacitor electrode based on the ordered mesoporous carbon material,and accelerate the industrialization of the ordered mesoporous carbon material as the supercapacitor electrode.