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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Organometallic Polymer - Graphene Nanocomposites: Promising Battery Materials

Beladi Mousavi, Seyyed Mohsen 27 January 2017 (has links)
Preparation, structural analysis, and electrochemical performance of a new cathodic battery material, consisting of a nanocomposite of poly(vinylferrocene) (PVFc) (Eox: 0.4 V vs. Ag/AgCl) and reduced graphene oxide (rGO), are described. The nanocomposite shows the highest charge-discharge efficiency (at a rate of 100 A g-1) ever reported for any organic / organomatellic battery material. Remarkably, the composite is “thickness scalable” up to 0.21 mAh cm-2 (770 mC cm−2 at 29 μm film thickness) on a flat surface with > 99% coloumbic efficiency, exhibiting a specific capacity density of 114 mAh g−1. The composite material is binder free and the charge storing material (PVFc) accounts for > 88% of the total weight of the cathodic material. The secret behind such a performance is the electrostatic interaction between the redox polymer in its oxidized state (exhibiting positive charge) and the original filler i.e., graphene oxide (GO) with negative surface charge. This self-assembling step is analyzed by zeta potential measurements, and a modeling study confirms the experimentally found heavy polymer loading on the GO (in aqueous solution). The efficient self-assembly led to composites with high ratio of redox polymer / GO where all polymers are in close contact with GO sheets. The stable colloidal solution was casted on the surface of a flat current collector and the insulating GO was electrochemically transformed to conductive reduced graphene oxide (rGO). The GO / rGO transformation was catalyzed by methyl viologen dichloride (MV++) working as a redox shuttle (solublized in the aqueous electrolyte) and thereby accelerating the electron transfer to GO. Complete GO / rGO transformation and the quantitative ion breathing of the composite are found by means of electrochemical quartz crystal microbalance and electrochemical AFM.

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