Structural Control Of Hierarchical Porous Carbon And Its Composites And Their Electrochemical Performance

As a new style storage energy device, supercapacitor has recently received wide attention due to its higher energy density than ordinary capacitor and power density than secondary battery. Electrode material is an important factor influencing its electrochemical properties. Generally, electrode materials include high specific surface carbon, metal oxide and conducting polymer, but carbon materials are still regarded as the most promising candidates because of their low cost, good conductivity and excellent physicochemical stability. Currently, electrochemical performance of carbon-based materials does not meet the commercial requirements. Therefore, much effort has been devoted to high-performance electrode materials for supercapacitor by controlling the structures of hierarchically porous carbons and their composites. The main work of this thesis is given as follows:1. Hierarchically porous carbons (HPCs) were synthesized by a template method with phenolic resin as carbon source and F127 as a soft template. The obtained HPCs with tunable core sizes of 242-420 nm exhibit large BET surface areas (-900m2 g-1) and large pore volumes (-1.2 cm3 g-1). The electrochemical properties of the HPCs with various core sizes used as supercapacitor electrodes materials were evaluated using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy techniques. The results show the HPCs with the core size of 242 nm possesses the largest specific capacitance (165 F g-1 at the current density of 0.1 A g-1) among the HPCs.2. The HPCs were fabricated by using hollow mesoporous silica sphere as a hard template and phenolic resin ethanol solution (20wt%) as carbon source. The morphology, core size and shell thickness of HPCs can be easily adjusted by controlling the amount of phenolic resin. The electrochemical properties of the HPCs with various amount of carbon source were evaluated. The results showed that the maximum specific capacitance of 256F/g could be obtained for the HPCs-0.5 at a current density of 0.1 A g-13. Hierarchical porous carbon/polyaniline nanowires nanocomposites have been prepared by template-free method in which polyaniline naonowires growing on the surface of HPC to form sea urchin-like composite. The electrochemical properties of the PANI/HPCs used as supercapacitor electrodes materials were evaluated and showed that the composite has a higher specific capacitor than hierarchical porous carbon, up to 452 F g-1 at a current density of 0.1 A g-1...