Formation of graphitic tubules from ordered mesoporous carbon and their effect on supercapacitive energy storage

Abstract

Mesoporous carbon materials with controlled pore and wall structures have promising applications in energy storage. In this work, we prepare a series of ordered mesoporous carbons (OMCs) by adjusting the pyrolysis temperature via a soft templating and catalytic graphitization approach. The structure of graphitic tubules formed in the pyrolysis process from the hexagonally ordered OMCs is investigated using electron tomography. It is observed that the long axis of the tubules is parallel to the mesochannels, i.e. along the [001] direction. The structural parameters and electrochemical properties of the OMCs are comprehensively characterized. From our systematic study it is concluded that in order to prepare OMCs with high capacitance, good retention and excellent cyclability, an optimised synthesis condition is adjusted at which graphitisation is maximised while the formation of graphitic tubules is inhibited. OMC synthesized at an optimum temperature of 800 °C provided a high specific gravimetric capacitance of 182 F g−1 at the current load of 0.025 A g−1 in 1 M H2SO4 and retained 74% capacitance at a high current load of 5 A g−1, whilst also providing a stable cycling performance up to 10 000 cycles at this strenuous load. Our work has shed new light on the designed synthesis of OMCs with improved performance as supercapacitors for energy storage applications.