In recent years, lithium-ion batteries have saturated the electronics market due to their widespread use in cell phones, laptop computers, and tablets. As a result, developers have spent billions of dollars to maximize their potential use.
But high costs, slow recharging rates, and limited lifetimes often restrict the utility of these batteries, which are also used for applications such as electric vehicles or to store electricity from wind or solar power. While scientists are working to resolve these deficiencies, only a few have focused on a key interaction that influences battery behavior—how lithium ions move from one electrode to the other.
Researchers at Lawrence Berkeley National Laboratory (Berkeley, California) and the University of California-Berkeley, however, have taken up the challenge. Using experiments and theoretical calculations, the researchers have shown that the lithium ion’s journey involves more intimate contact with electrolyte molecules than previously thought.
The findings suggest that computational models need to be refined to account for the higher number of electrolyte molecules surrounding the lithium ion (its solvation structure) when representing the lithium ion-electrolyte interaction.
The improved modeling of the lithium ion solvation structure could allow lithium-ion batteries to take on new applications, the researchers say.
Using liquid microjets to measure x-ray absorption spectra—interpreted using first-principles theory calculations—the researchers determined that the lithium ion has a solvation number of 4.5, which varies from the expected tetrahedral structure.
This suggests that future computational models should expand beyond the current tetrahedral model to improve upon the electrolytes within the battery. The improvement of the battery based on these findings could also be another step towards making the batteries even more useful for large-scale applications.
This work was supported by the U.S. Department of Energy’s Office of Science (Washington, DC), within its basic energy services office and the chemical sciences, geosciences, and biosciences division.
Resources at the Advanced Light Source (Berkeley, California), Molecular Foundry (Berkeley, California), and the U.S. National Energy Research Scientific Computing Center (Berkeley, California) were also used.
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