Computational model developed at CINE enables sodium ion batteries optimization
Lithium-ion batteries are currently the favorites of the industry. Well consolidated and disseminated in the market, this technology makes it possible to manufacture lightweight devices with high energy density. However, other technologies emerge as alternatives, or even substitutes, mainly because they promise lower costs and more sustainability. One of the most promising in this regard is the sodium ion technology. These batteries are very similar in structure and operation to lithium, but they are based on sodium – a more abundant element, better distributed geographically and which can be extracted by cleaner and simpler processes than lithium.
However, the sodium ion technology still needs to be optimized and, for this, one of the main challenges is to understand in detail the transport mechanisms of the sodium ions, which travel through the battery electrolyte in the charging and discharging processes. Such understanding can be achieved through atomistic computational studies, which have been very little used so far for this purpose, due to the large amount of time they need to meet the required level of detail.
Recently, a team of CINE members and collaborators developed simplified computational models that enable the precise study of these mechanisms in ionic liquids – materials with potential for use in sodium ion battery electrolytes.
The models developed by these researchers are of the ‘coarse-grained’ type, which is characterized by replacing a set of atoms of a given molecule by simplified interaction sites. “This reduces the long calculation/simulation times of atomistic models, which allows simulating representative systems of thousands of atoms and for long simulation times”, explains Rafael Maglia de Souza, one of the authors of the study.
From the application of these coarse-grained models, the team was able to describe phenomena that are very relevant to the performance of batteries, such as the formation of sodium and ionic liquid aggregates, and their impact on the transport of sodium ions. The study results can be used to develop better sodium ion batteries. “This new understanding allows us to optimize the conditions of the electrolyte (such as the concentration of sodium present in the ionic liquid) aiming at better battery performance”, says Rafael, who started the study during his doctorate at FFCLRP-USP, under the guidance of Professor Luis Gustavo Dias, and completed it as a postdoctoral fellow at IQ-USP. During his doctorate, he did a research internship at The University of Western Ontario (Canada) where he received guidance from Professor Mikko Karttunen, who is also a co-author of the research. The study simulations were performed using Brazilian (HPC-USP) and Canadian (ComputeCanada) computational resources.
Paper: Development of coarse-grained force field to investigate sodium-ion transport mechanisms in cyanoborate-based ionic liquid. Rafael Maglia de Souza, Tuanan C. Lourenço, Leonardo José Amaral de Siqueira, Mikko Karttunen, Juarez L. F. Da Silva, Luis Gustavo Dias. Journal of Molecular Liquids. Volume 338, 15 September 2021, 116648. https://doi.org/10.1016/j.molliq.2021.116648
Authors who are or were members of CINE: Rafael Maglia de Souza (postdoc, FFCLRP- USP), Tuanan C. Lourenço (postdoc, IQSC-USP), Leonardo José Amaral de Siqueira (Professor at UNIFESP Diadema) , Juarez L. F. Da Silva (Professor at IQSC-USP), Luis Gustavo Dias (Professor at FFCLRP-USP).