Synthesis And Electropolymerization Of C₆₀ Derivatives And Their Applications For Supercapacitors

Supercapacitors, named Electrochemical capacitors（ECs）. As a new-style energy store and conversion devices between traditional capacitors and batteries, supercapacitors possess a significant amount of outstanding properties, such as high power density, long-time cycle life, shot-time for charging, high stability and security. So, it not only attracts intensive attention of the researcher, but becomes a important filed, to which the companies invest huge funds around the world, for the improving technology and the dramatically rising market demand. As one kind of the supercapacitors electrode materials, organic conductin g polymers（CPs） have much potential, because their high conductivity, relatively high specific capacitance, large operating potential and low cost. Electropolymerization is a simple but very important way for the synthesis of organic conjugated polymers, via the way we can control the structure and morphology of the film by control the conditions and the methods of electropolymerization. What’s more, we can gain a high quality and functionally film.Most of the organic conducting polymers just tend to be p-doping, and very little to be n-doping or even p-/n-doping, which limit the enhancement of specific capacitance and operating potential. Therefore, the specific power and specific energy is hard to be improved. Fullerene C₆₀ has become an important material with fascinating optoelectronic properties in organic electronics because of its high electron affinity, three-fold degenerate lowest unoccupied molecular orbital（LUMO）, and 3D electron transporting abilities. And C₆₀ is a typical n-doping material. Based on these considerations, herein, we set the topic “Synthesis and electropolymerizaion of C₆₀ derivatives and their applications for supercapacitors”. Detailed research contents are as follows:Firstly, we designed and synthesized the C₆₀ derivative—2Cz-C₆₀, 4Cz-C₆₀, 6Cz-C₆₀, which were used for further polymerization via the electrochemical-coupling of N-alkyl caazole units to form a linear or cross-linked polymer film—Poly[2Cz-C₆₀], Poly[4Cz-C₆₀] and Poly[6Cz-C₆₀]. And the thickness of the film can be controlled precisely by controlling the cycles of CV. Since their bipolar properties, fast and reversible redox, the organic conducting polymers films show outstanding performance as the supercapacitors electrode materials. Their operating potentials reach up to 3.2V, 2.9V and 2.7V, respectively. The specific capacitances are calculated from the discharge parts of galvanostatic experiment. A maximum capacitance of 306.2, 217 and 205 F g-1 are obtained at current density of 5A g-1 respectively. What’s more, the capacitance could retain as high as 70%, 85% and 86%, respectively.Secondly, we designed our monomer C₆₀Me5 Th, which bears five 3-phenylthiphene groups linked at a C5 geometry to yield a shuttlecock-shape structure. The 3-phenylthiphene group is well established as a highly electroactive unit, which enables effective coupling reaction between its oxidative species（thienyl radical cation） and form highly conjugated polythiophene（PTh） backbones. Herein we report the first demonstration of the controlled and direct electrochemical synthesis of highly electroactive fullerene-based CMP films, which are prepared in large area with high quality, and are compatible with device fabrication. We demonstrate the controlled synthesis of thin films with different thicknesses of nanometer precision. The C₆₀Me5Th-CMP films own superb properties, including their porosities, band gaps, and their functions as supercapacitive materials in energy storage. It with a BET surface area of 695m2 g–1, and the pore size distribution was calculated to be 0.5n m. A maximum capacitance of 463 F g-1 is obtained at current density of 5A g-1. This is among the best values reported on pure conducting polymer based electrodes. The capacitance could retain as high as 63% when the current density increased from 5A g-1 to 50 A g-1...