For decades, we’ve known about the protective benefits toothpaste has on our teeth. But recently, scientists at the Department of Energy’s Argonne National Laboratory may have discovered a new use for this abundant and unassuming product – protecting next-generation non-lithium-ion batteries against performance decline.
Non-lithium-ion batteries boast an energy storage capacity double that of lithium-ion batteries, meaning they provide greater driving distance for electric vehicles of all sizes and weights. However, non-lithium-ion batteries’ high energy density declines rapidly as they are charged and discharged.
To solve this challenge, scientists began looking at toothpaste – or, more specifically, in toothpaste. What they found was an abundance of sodium fluoride, a compound of fluorine known for its ability to protect teeth from decay. Within this compound, they discovered a fluoride electrolyte, which is a liquid that lithium ions use to move between the cathode and anode to create a charge and discharge.
In lithium metal batteries, it’s common to find the electrolyte is a liquid composed of lithium-containing salt dissolved in a solvent. This electrolyte does not form an adequate protective layer during the first few cycles, meaning battery performance will deplete quickly after the first several uses.
However, when scientists applied the fluoride electrolyte from the toothpaste, they found that it created an impressive protective layer that was able to last for hundreds of cycles. Part of the reason for its success is its ion makeup. This new fluoride solvent combines both positively charged and negatively charged fluorinated components, forming what is known as an ionic liquid.
“Lithium metal batteries with our fluorinated cation electrolyte could considerably boost the electric vehicle industry, and the usefulness of this electrolyte undoubtedly extends to other types of advanced battery systems beyond lithium-ion,” said John Zhang, Group Leader in Argonne’s Chemical Sciences and Engineering division.
This new electrolyte offers several benefits. Because an extremely high yield can be achieved in one step rather than multiple, it has a relatively lower associated cost. The electrolyte also uses much less solvent, which is volatile and releases contaminants, making it more environmentally friendly. The electrolyte is also not flammable, making it a safer option.
“Lithium metal batteries with our fluorinated cation electrolyte could considerably boost the electric vehicle industry,” said Zhang. “And the usefulness of this electrolyte undoubtedly extends to other types of advanced battery systems beyond lithium-ion.”