Preparation And Performance Improvement Of Ordered Mesoporous Carbon Materials For Supercapacitors

Supercapacitors have received widely attention due to the advantages of high power density, fast charge/discharge processes, long cycle life, low cost and environmental friendly. It is well known that the electrode material is the key component for high performance supercapacitor. As a consequence, it is great significant to design high performance electrode materials for the development and application of supercapacitor. At present, carbon materials have been widely used as EDLCs electrode because of their high specific surface areas, chemical stability and excellent electrical conductivity. Ordered mesoporous carbons(OMCs) are one of particularly attractive carbon material due to their inherent structural characteristics that include developed porosity structure and uniform pore size distribution, which can facilitate ion diffusion. In this paper, 3D cubic-ordered mesoporous carbons have been successfully synthesized employing KIT-6 silica as the template. And in order to further enhance the supercapacitive performance of the OMCs, MnO2/OMCs with nanosized MnO2 embedded in ordered mesoporous carbons and boron-doped ordered mesoporous carbons have been prepared, and the results are meaningful. The main work in this paper is as follows:Firstly, 3D cubic-ordered mesoporous carbons are synthesized employing KIT-6 silica as the template, furfuryl alcohol as the carbon source at the temperature ranging from 500 oC to 700 oC, and the effects of carbonization temperatures on structure, electrochemical performance and supercapacitive behaviors of OMCs are further investigated. The results show that the as-prepared OMCs exhibit high specific surface areas and uniform pore size distribution. The OMC-600 possesses ordered mesostruture and excellent electrochemical performance. The OMC-600 electrode obtains the specific capacitance of 256.86 F g-1 and 220.3 F g-1 from at the scan rate is 1 mV s-1 and current density of 1 A g-1, respectively. The OMC-600 supercapacitor displays good cycle stability, and the specific capacitance keeps 90% after 10000 consecutive cycles. Besides, the OMC-600 supercapacitor obtains the energy density of 6.96 Wh kg-1 and 6.53 Wh kg-1 at the power density of 1000 W kg-1 and 5000 W kg-1, respectively.Secondly, the MnO2/ordered mesoporous carbon composites(MnO2/OMCs) are prepared by the redox reaction of KMnO4 with ordered mesoporous carbon CMK-8 synthesized by KIT-6 as the hard template. And the effect of different MnO2 loading amount on the physical and electrochemical performances of MnO2/OMCs are extensively investigated in detail. The results show that MnO2/OMCs can still maintain the ordered mesostructure and the ordered structure is slightly damaged with the increase of MnO2 loading amount. And MnO2/OMC-0.04 electrode shows excellent electrochemical performance, in which the specific capacitance reaches 576.10 F g-1 at the scan rate of 1 mV s-1 and 554.8 F g-1 at the current density of 1 A g-1, respectively. In addition, the coulombic efficiency of MnO2/OMC-0.04 is almost 100% during the whole charge/discharge cycling process, which implies the good reversibility and excellent electrochemical stability of MnO2/OMC-0.04.Finally, in order to further improve the electrochemical performance of ordered mesoporous carbons, the boron-doped ordered mesoporous carbons(BOMCs) with different boron content are prepared and the effects of different boron content on physical and electrochemical performances are extensively investigated in detail. It can be found that the ordered mesoporous structures are maintained after the incorporation of appropriate amount of boron, and the BOMCs exhibit high specific surface areas and narrow pore size distribution. Moreover, the BOMCs exhibit enhanced electrochemical performance compared to the pristine OMC, and the BOMC-0.05 electrode obtains a high specific capacitance of 267.8 F g-1 at the scan rate of 5 mV s-1. At the same time, the symmetrical supercapacitor using BOMC-0.05 as electrode shows a specific capacitance of as high as 69.8 F g-1 and excellent cyclic stability with the specific capacitance retention of 92% even after 10000 consecutive cycles.