A recent computational study has made significant strides in enhancing the safety and performance of future battery technologies. Published in the Journal of Molecular Liquids, the research investigates new compounds that can serve as electrolytes in sodium-ion batteries, a promising alternative to traditional lithium-ion systems. The study was conducted by a collaborative team associated with the Center for Innovation on New Energies (CINE), which includes researchers from the State University of Campinas (UNICAMP), the University of São Paulo (USP), and the Federal University of São Carlos (UFSCar), along with experts from the University of Bonn in Germany.
Sodium-ion batteries offer an environmentally friendly alternative due to sodium’s abundance on Earth. These batteries operate by facilitating the movement of sodium ions between electrodes through the electrolyte during charging and discharging cycles. The most explored electrolytes are ionic liquids, a class of salts that remain liquid at room temperature and are known for their excellent ion conductivity and non-flammability, enhancing battery safety.
Despite their advantages, sodium ions tend to increase the viscosity of these ionic liquids, which can hinder ion mobility and degrade electrolyte performance. To address this challenge, the CINE team explored electrolytes based on two types of ionic liquids: aprotic, which is commonly used in research, and protic, which is less expensive to produce but has not been extensively studied.
The researchers aimed to enhance ion mobility by adding sodium salt to these ionic liquid compounds. Tuanan da Costa Lourenço, a postdoctoral researcher at CINE and the corresponding author of the article, highlighted the core focus of the work: “The main point of this work was to evaluate the effect of increasing the concentration of sodium salt in an electrolyte based on a protic ionic liquid and its analog containing an aprotic ionic liquid.”
To conduct the study, the team utilized molecular dynamics simulations, a computational technique that models the interactions of atoms and molecules. This involved the use of numerous interconnected computers and advanced software to solve complex mathematical equations. The research benefitted from computational resources provided by USP, the National Laboratory for Scientific Computing (LNCC), and the University of Bonn.
The findings revealed that increasing sodium salt concentration alters the organization and interactions of ions within the ionic liquid. Notably, the study demonstrated that the extent of these changes is influenced by the molecular structure of the ions and the type of ionic liquid used. Lourenço stated, “Additionally, we observed that at high sodium salt concentrations, there’s a decrease in the interaction forces between the sodium ion and the electrolyte anion, which can be beneficial for battery performance.”
International collaboration is a hallmark of this research. The Computational Materials Design (CMD) program at CINE, led by Juarez Lopes Ferreira da Silva, aims to identify promising electrolytes for advanced batteries. The project brought together members from USP and the research group of Barbara Kirchner at the University of Bonn, who specializes in modeling complex liquid systems.
Lourenço emphasized the impact of this collaboration, stating, “The collaboration not only made it possible to deepen the discussion and conclusions obtained, but also resulted in the development of new tools, improvements to the models used, and new collaborations.” He dedicated 15 months to this project within Kirchner’s group.
The research team is currently pursuing additional studies to further understand how to modulate ion interactions in ionic liquids, with the goal of optimizing battery performance. This innovative approach could pave the way for the next generation of safe, high-performance batteries, addressing the growing energy storage needs from renewable sources such as solar and wind.
