Screening of Electrolytes Based on Deep Eutectic Solvents via Computational Techniques.

• Grant number: 24/23708-3
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: May 01, 2025
• End date: January 31, 2030
• Field of knowledge: Physical Sciences and Mathematics - Physics - Atomic and Molecular Physics
• Principal Investigator: Juarez Lopes Ferreira da Silva
• Grantee: Luana Schneider Moreira
• Host Institution: Instituto de Química de São Carlos (IQSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Company: Universidade de São Paulo (USP). Instituto de Química de São Carlos (IQSC)
• Associated research grant: 17/11631-2 - CINE: computational materials design based on atomistic simulations, meso-scale, multi-physics, and artificial intelligence for energy applications, AP.PCPE

Abstract

Batteries store a significant amount of energy in a small space, provide energy rapidly when needed, and can undergo multiple charge and discharge cycles with minimal capacity loss. These devices are essential for renewable energy storage, as renewable energy depends on unpredictable natural resources and is crucial to addressing the growing environmental crisis caused by carbon dioxide emissions. Among existing batteries, lithium-ion batteries are extremely popular, however, lithium is unevenly distributed across the globe and scarce in the Earth's crust. In contrast, sodium is abundantly available, making sodium-ion batteries a lower-cost alternative that is less vulnerable to raw material supply risks.The development of suitable materials for the anode, cathode, and electrolyte is essential for the practical feasibility of sodium-ion batteries. Among these components, the electrolyte plays a substantial role by transporting ions between the electrodes. A promising approach to making these batteries more sustainable and cost-effective lies in the use of electrolytes based on deep eutectic solvents (DESs), a mixture of two or three components that form associations through hydrogen bonds, reducing the melting point compared to the pure substances. Similar to ionic liquids (ILs), DESs possess high thermal stability and low volatility, however, they are generally cheaper, biodegradable, non-toxic, and easier to prepare than ILs.To find the best electrolyte for sodium-ion batteries, several questions must be analyzed and answered, such as: Why does increasing the salt concentration in DESs generally lead to greater electrochemical stability but lower ionic conductivity and higher viscosity? How does temperature affect the electrochemical stability window -- an essential question for determining the viability of the electrolyte under different operating conditions --? How do different hydrogen bond donors and acceptors, at varying molar ratios, and the incorporation of additives into the electrolyte affect conductivity? What is the impact of residual water on the stability and performance of hygroscopic electrolytes? Which electrolyte has the lowest flammability?To understand these phenomena and find answers, computational methods such as Molecular Dynamics and Density Functional Theory have proven to be powerful tools for studying DESs. Molecular dynamics is a widely used technique in electrolyte studies, as it allows for the characterization of structural, transport, and energetic properties at the atomic level, facilitating correlation with experimental data. In this PhD project, we will use the computational approach recently published by the QTNano group to study electrolytes, which combines the OPLS force field with periodic density functional theory (DFT) calculations. Essentially, the atomic charges used in the calculation of Coulomb interactions will be determined via DFT for the systems in the bulk phase, while the other parameters will be obtained directly from the OPLS force field, enabling a better description of the structural and transport properties of electrolytes.