Atomic scale modelling of organic electrode materials

• Autor(a) principal: Fernandes, Marcela Lopes
• Data de Publicação: 2023
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://www.teses.usp.br/teses/disponiveis/43/43134/tde-19102023-232737/
• topic: algoritmo genético; baterias orgânicas; DFT; DFT; genetic algorithm; lithium; lítio; organic batteries

Due to several environmental issues related to the high consumption of energy, the search for higher energy storage and environmentally friendly devices was necessary. The Li-ion batteries are commercially used and known for its great efficiency. However, most commercially used batteries are all inorganic. Hence, some compounds found in these batteries are harmful to the environment and hardly recyclable. In this sense, organic lithium batteries have showed to be a good alternative to the well known batteries. There are many challenges that need to be overcome for the commercially use of an organic battery. These issues are intrinsically connected to the electrochemical properties of the electrode. In this master thesis, we analyzed and simulated, at atomic level, the changes in the organic electrode properties by changing the \"spectator cation\" in the material structure. In order to predict the crystalline structure of the materials, we performed the genetic algorithm, USPEX, interchanged with calculations in the framework of Density Functional Theory (DFT) performed by VASP software. Furthermore, the voltage, the density of states (DOS) and the partial charge related to each lithiation step was calculated. The electrode is composed by the ligand DHT (terephthalate), lithium ions and the spectator cations (Mg+2, Na+, Ca+2). The calculated voltages for the materials MgLi2DHT, Na2Li2DHT and CaLi2DHT, were respectively 3,59 V, 2,96 V and 2,98 V. The density of states (DOS) shows the material\'s reaction to receiving an electron. On the other hand, the Bader charge analysis shows the charge difference for each part of the material when compared to the other ions. Our obtained results agree with previous experimental results. Successfully, we simulated the voltage rise for the battery material with the magnesium ion, and we obtained a greater understanding of the structure and electronic properties for the studied organic electrodes.