Host-guest Inclusion Complexes Derived Heteroatom-doped Carbon Materials For Electrochemical Supercapacitors

Supercapacitors, also named electrochemical capacitors, which bridge the gap between batteries and traditional capacitors, are new and hot energy storage devices. Due to their short charging time, high power density, and long cycling life, supercapacitors have been widely used in the area of electronics, transportation, telecommunications, energy storage systems and so on.The performance of supercapacitors is closely related to the electrode materials. A lot of work has been done to prepare a high-performance electrode material. Due to their high conductivity, excellent chemical stability and large surface area, carbon materials become ideal candidates used as the electrode materials for electrical double layer capacitors(EDLCs). To further improve the specific capacitance and energy density of supercapacitor, the development of novel carbon precursor and new synthetic methods for preparing heteroatom doped carbon material, which have a stable graphite framework, high specific surface area, controllable space structure and reasonable pore size distribution, is a challenge in the field. In order to solve the problems encountered in the fabrication of carbon materials, β-cyclodextrin(β-CD), has been selected as carbon precursor to prepare heteroatom-doped and high specific surface area of carbon materials for electrochemical supercapacitors in this study. The main contents and conclusions are summed up as follows:(1) We prepared heteroatom-doped carbon materials derived from host-guest inclusion complexes based on β-CD. The host compound, β-CD acted as the carbon precursor, while a series of heteroatom-containing small molecules, such as p-aminoazobenzene, amantadine, 1-dodecylimidazole, and multiple heteroatom containing(nitrogen, sulfur, boron and fluorine et. al.) ionic liquids were selected as the guest molecule without complicated organic synthesis, which provided both the carbon and heteroatom sources. Inclusion of these guest molecules into the cavity of host not only implanted the carbon frameworks with heteroatoms, but also highly improved the carbonization yield. A nitrogen-doped porous carbon material derived from inclusion complexes exhibited a high performance as supercapacitors electrode with a high specific capacitance(348 F g-1) at a current density of 1 A g-1 in 6 M KOH aqueous solution and good cycling stability over 5000 cycles, demonstrating its potential application in energy storage. This work provides an easy and efficient method for large-scale preparation of heteroatom doped CMs.(2) To further optimize the structure and properties of carbon materials, a new procedure for preparing Fe/N co-doped carbon materials was designed. The carbon materials were prepared via hydrothermal carbonization of host-guest inclusion complexes of β-CD(served as carbon precursor) and ferrocene(Fc), which acts as Fe source and pore-forming agent, and are applied to supercapacitor. NH4 Cl was used as pore-forming agent and nitrogen source. More in depth studies about the relationship between the structure or heteroatom content of carbon materials and energy storage capability was realized through investigation of the performance of carbon material derived at different temperatures as supercapacitor electrode. This work provides theoretical guidance for the design of new non-precious metals and heteroatom co-doped porous carbon material.