Electrochemical Characterizations of Conducting Redox Polymers : Electron Transport in PEDOT/Quinone Systems

Sammanfattning: Organic electrode materials for rechargeable batteries have caught increasing attention since they can be used in new innovative applications such as flexible electronics and smart fabrics. They can provide safer and more environmentally friendly devices than traditional batteries made from metals. Conducting polymers constitute an interesting class of organic electrode materials that have been thoroughly studied for battery applications. They have high conductivity but are heavy relative to their energy storage ability and will hence form batteries with low weight capacity. Quinones, on the other hand, are low weight molecules that participate in electron transport in both animals and plants. They could provide batteries with high capacity but are easily dissolved in the electrolyte and have low conductivity. These two constituents can be combined into a conducting redox polymer that has both high conductivity and high capacity. In the present work, the conducting polymer PEDOT and the simplest quinone, benzoquinone, are covalently attached and form the conducting redox polymer used for most studies in this thesis. The charge transport mechanism is investigated by in situ conductivity measurements and is found to mainly be governed by band transport. Other properties such as packing, kinetics, mass changes, and spectral changes are also studied. A polymerization technique is also analyzed, that allows for polymerization from a deposited layer. Lastly, two different types of batteries using conducting redox polymers are constructed. The thesis gives insight into the fundamental properties of conducting redox polymers and paves the way for the future of organic electronics.