Researchers at the Georgia Institute of Technology are trying to counter the rise in the price of lithium-ion batteries with a new battery design, and are starting at the point that is largely responsible for said development: the increasing global demand for the metals cobalt and nickel in the battery production industry. The research team has now developed a cathode and electrolyte system that replaces expensive metals and traditional liquid electrolytes with cheaper transition metal fluorides and a solid polymer electrolyte.
In summary, the research team produced a new type of cathode from iron fluoride active material and a solid polymer electrolyte nanocomposite. Iron fluorides have more than twice the lithium capacity of conventional cobalt- or nickel-based cathodes. In addition, iron is many times cheaper than the metals traditionally used.
The researchers discovered that the solid electrolyte could be a key factor for an improved battery performance. In the newly published study, the researchers explain that in earlier attempts to use metal fluorides, it was assumed that metal ions migrated to the surface of the cathode and eventually dissolved in the liquid electrolyte, resulting in a loss of capacity, especially at elevated temperatures. However, the researchers observed that there is no such dissolution at the connection between the solid electrolyte and the cathode, and the solid electrolyte remains remarkably stable, which prevents the assumed degradation.
Gleb Yushin, professor at Georgia Tech's School of Materials Science and Engineering stated: “Cathodes made from iron fluoride have enormous potential because of their high capacity, low material costs and very broad availability of iron. But the volume changes during cycling as well as parasitic side reactions with liquid electrolytes and other degradation issues have limited their use previously. Using a solid electrolyte with elastic properties solves many of these problems.”
The study was first published in Nature Materials on 9 September and was funded by the Army Research Office.
Source: Georgia Institute of Technology | www.news.gatech.edu
Image: Georgia Institute of Technology/Allison Carter | www.news.gatech.edu
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