Bettencourt, Katherine Valentina da Silva2026-01-072026-01-072025http://hdl.handle.net/10400.5/116516Tese de Mestrado, Química, 2025, Universidade de Lisboa, Faculdade de CiênciasLithium-ion batteries are every day at the palm of our hands in smartphones, laptops, and watches. However, with their growing demand, environmental repercussions have come to light, creating an urgent need for alternative battery chemistries. Sodium-ion batteries are a promising alternative due to their natural abundance and chemical similarity to lithium. Despite this, Li-ion technology cannot be directly applied to Na-ion systems since the larger sodium ions destabilize crystalline matrices during battery cycles, making it necessary to rethink electrode materials. Organic cathode materials have gained attention for sodium-ion batteries, being flexible, sustainable, and cost-effective. Among them, carbonyl compounds and conducting polymers stand out. Yet, their low energy densities limit their use. To address this, the present work intends to combine both materials to give place to a hybrid coating with improved stability that can be further modified to increase the specific capacity of the material. In this work, dopamine (DA) and 3,4-ethylenedioxythiophene (EDOT) were electropolymerized to combine their distinct functionalities into a copolymer with enhanced properties. PDA offers strong surface adhesion and easy chemical modification, while PEDOT is known for its good conductivity and chemical stability. During this study, the electrosynthesis of a PDA/PEDOT copolymer was explored, testing various applied potentials, electrolytes, and monomer proportions to optimize it as a cathode. The extensive physicochemical characterization of the copolymer supported the successful combination of these materials, with the electroactivity of the film showing the typical pseudocapacity of PEDOT and the quinone/catechol redox of PDA. Techniques such as FTIR, Raman, AFM, ellipsometry, and in-situ UV-vis, alongside electrochemical methods, allowed detailed analysis of the film’s composition, morphology, thickness, and optoelectronic properties. When tested as cathode, the copolymer showed greater stability and specific capacities than PEDOT, retaining 96 % capacity after 1500 cycles, highlighting its potential as a platform for next-generation hybrid organic cathodes.application/pdfengPolydopaminePEDOTConducting PolymersElectrocopolymerizationSodium-Ion Batteriesmaster thesis204174163