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Nanocellulose in conductive materials Lauri Matikainen
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Introduction Conductivity Utilization Ionic solutions Plasmas Superconductors Quantity: σ (sigma), Unit: S/cm (Siemens – Reciprocal to resistance and Ohm) Capacitance C = ϵ 0 ϵ r A/d, Unit: F (Faraday) Describes the capacity to conserve electricity
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Capacitors Supercapacitor Conventional capacitor 1.Power source 2.Collector 3.Polarized electrode 4.Hemholz double layer 5.Electrolyte having positive and negative ions (uncharged) 6.Separator Target in this study: To enhance the electrostatic attraction of electrodes
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Background Typical material of an electrode: Active carbon, graphene, carbon nanotube, etc. Suggested material of an electrode: Cellulose nanocrystals/Polypyrrole – CNC/PPy Comparable properties: Flexible, lightweight, “wearable” The properties follow the PPy/OH relation (Polypyrrole to CNC OH-groups) The OH-groups were introduced to CNC by TEMPO-oxidation
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Results Figure 1: Optimal PPy/OH ratio = 16:1 The one-dimensional structure of CNC contributes to the conductivity Figure 2: The relation of weight% to temperature between the following combinations: TempoCNC, PPyCNC, and Pure PPy Figure 3: PPy-CNC blend used as a series circuit
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Capacitance comparison Substance Specific capacitance (F/g) CNC/PPy 248 Active carbon 100 Graphene (theoretical) 550 Single-walled nanotubes (SWNT) 180 Multi-walled nanotubes (MWNT) 102
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Conclusion CNC/polypyrrole blend is a convenient alternative to enhance the performance of supercapacitors CNC is made conductive by TEMPO oxidation, which adds carboxylate groups possessing a surface charge By grafting, polypyrrole end groups can be added to CNC, which improves its advantages Being flexible, lightweight and wearable, CNC/PPy systems are a competitive alternative for carbon derivatives to be used as electrodes in the future
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References 1. Pearson International Edition: Wolfson Essential University Physics, Volume 2. 2. Wu, X. et. al. : Cost-effective and Scalable Chemical Synthesis of Conductive Cellulose Nanocrystals for High-performance Supercapacitors. Electrochimica Acta, 2014. 3. Lecture slides: Cellulose Physical Aspects. Orlando Rojas, 2015.
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