engleski

Nanoporous Polymers as Electrodes in Supercapacitors

Nanoporous conducting polymers have shown superior ability to store ionic charge in comparison to the high surface area carbons, which are at present used in supercapacitors (1). As for supercapacitors, they are unique energy storage devices presenting high technological interest due basically to their high power density and long durability. The mechanism of energy storage in these devices divides them in two main groups: electrochemical double layer capacitors and redox supercapacitors. In the former, energy storage arises mainly from the separation of electronic and ionic charge at the interface between high specific area electrode materials and the electrolyte. In the latter, faradaic reactions take place at the electrode materials at characteristic potentials and give rise to what is known as pseudocapacitance. The amount of electrical energy accumulated in a supercapacitor is proportional to the capacitance. The value of capacitance is connected with the nature of the interface electrode-electrolyte. The higher the specific surface area, the higher will be the capacitance arising from the increased ability for charge accumulation at the interface. However, this surface must be accessible for the ions of the electrolyte, so, in addition of high specific surface area, the dimension of pores of electrode material should be adapted to the size of solvated anions and cations in the electrolyte. In order to replace toxic and carcinogen monomers, we have used harmless, cheaper and commercially easily available polymers in our preparation. We have prepared: 1. Porous polymer by co-dissolution of polystyrene and malachite green in common solvent. After removal of dye compound by dissolution, rinsing with alcohol was performed. Films were characterized by Field Emission Microscope SEM Zeiss Supra 35 VP. 2. Porous polymer by dissolution of the chosen polymer with suspension of calcium carbonate in a common solvent and subsequent evaporation in normal atmosphere for two days. Films were characterized by Optical Microscope Zeiss Aksiovert 35. The advantages gained by use of the new nanoporous materials in supercapacitors are in their ability to store a higher concentration of ionic charge carriers than in state-of-the-art electrodes. Another distinct advantage with the use of the new electrode materials is that they may be used without incorporation of liquid electrolytes. An all-solid state supercapacitor will be operable over a much wider range of temperatures than that with a device containing liquid electrolyte. There is also the added advantage that a higher voltage can be applied for charging an all solid- state capacitor without fear of electrolytic decomposition. Reference 1) A. Gilmour, M. Gardner, A.Turković, I.Cendoya, M.Gaberšek, Supercapacitors for High Energy Density Electrical Storage, SHEDES, 17th , No

nanoporous polmers; supercapacitors

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