Desenvolvimento de pseudocapacitores a partir de compósitos de óxidos metálicos e materiais de carbono

Author(s)

Willian Gonçalves Nunes

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia Elétrica e de Computação
• Defense date: 2023-07-31

Examining board members

Hudson Giovani Zanin; Leonardo Moraes da Silva; Fabio Coutinho Antunes; Reinaldo Cesar; Bruno Bitarães Neto Salgado Brandão

• Advisor: Hudson Giovani Zanin

Abstract

The development of electrochemical capacitors (EC's), which reversibly store large amounts of energy and allow its quick release into electrical systems, is of paramount importance in scientific and technological research. Some applications of these devices are in modern electric vehicles [1], solar and wind energy storage systems, among others. In view of the importance of the development and continuous improvement of these auxiliary devices in energy storage, this research focuses on the development of stable EC's that maintain their intrinsic characteristic of high power and mainly seeks the combination of chemical elements capable of improving and consequently increasing significantly increases the energy storage capacity with high cyclability. The EC's studied in this scientific research belong to the class of pseudocapacitors whose main characteristic is to promote superficial redox reactions in the solid state capable of substantially increasing (e.g., up to 3 orders of magnitude) the energy storage of the EC's [2,3]. In this context, in the first part of this research a comparative study of the aging of nanostructured porous carbon electrodes in the presence of organic and aqueous electrolyte is presented. Subsequently, we present nanoparticles of nickel and manganese oxide decorating carbon-based electrodes with an extensive characterization of the materials associated with the study Operando of the device. Following studies of electrodes decorated with metallic oxides, we report characterizations of nickel oxide nanoparticles decorating carbon fiber electrodes. For a more in-depth characterization, we combined Operando Raman and computational characterizations to understand the electrode and electrolyte interface of electrochemical pseudocapacitors (EPC's) devices. After, studies using metal oxides, we decorated carbon electrodes using conductive polymer (e.g., polyaniline). Here we report the degradation of polyaniline at high working stress windows through a combination of theoretical (e.g., computational) and experimental (Operando Raman) analysis. Finally, we carried out studies using spinel (e.g., crystalline structure composed of 3 different metallic oxides such as Aluminum, Cobalt and Manganese) decorating carbon electrodes that provided an increase in the pseudocapacitive working window above (e.g., from 1.0V to 1.4V) for electrolyte in aqueous medium. This increase in the working voltage window (V) becomes expressive for the energy storage (E) of EC’s since the stored energy is directly proportional to the capacitance (C) and proportional to the square of the voltage window (e.g., E = (CV²)/2). The aforementioned studies developed throughout this research published in journals present an extensive ex-situ characterization of the materials, in-situ electrochemical characterizations and analyzes of the Operando devices (AU)

• FAPESP's process: 18/20756-6 - Pseudocapacitors from metal oxides and activated carbon composites
• Grantee: Willian Gonçalves Nunes
• Support Opportunities: Scholarships in Brazil - Doctorate