A recent study published in the December issue of the Journal of Materials Chemistry A proposes the design of a fluorine battery instead of a lithium battery. Fluorine is a more resourceful alternative material than lithium.
Most batteries now use lithium and cobalt, both of which are rare elements. Researchers in Japan are also developing fluorine ion batteries to replace lithium batteries as car batteries. They say fluorine batteries can run 1000 km on a single charge. It’s just that the current fluorine ion batteries have a short charge/discharge life and break down quickly under the charge and discharge cycles.
This study says that an alternative fluorine ion battery design was used that could solve this problem.
The new design uses a layered ionic compound (electride) system, said Rohan Mishra, an assistant professor of mechanical engineering and materials science at Washington University in St. Louis.
Mishra said ionic compounds are a relatively new material and have been introduced in theory for about 50 years, but it is only in the last 10-15 years that scientists have begun to understand their properties.
In ordinary conducting materials, electrons flow around the crystal like “seawater,” while in ionic compounds, electrons are negative ions that reside in specific interstitial locations within the crystal structure like ions.
We predict that these interstitial electrons can be easily replaced by fluorine ions without significant impact on the crystal structure, enabling charge and discharge cycles,” Mishra said. Fluorine ions are also easy to move and distribute evenly due to the relatively open structural features of layered ionic compounds.”
This study identified this design solution from a large number of candidate materials with the help of quantum mechanical calculations performed by artificial intelligence: introducing fluoride into the interstices of a layered ionic compound composed of dicalcium nitride and yttrium subcarbide.
The use of artificial intelligence to assist in material design is an approach now used in many research fields. Traditional material design requires a time-consuming and costly process of designing, testing in the lab with physical objects, changing materials, and designing again, over and over again. The use of artificial intelligence can dramatically reduce development time by automatically suggesting solutions with better possibilities for researchers from within big data.
Co-investigator Steven Hartman of Los Alamos National Laboratory said that, in theory, adding fluoride ions to conventional electrode materials stores electricity well, but during the charge and discharge process, these electrode materials expand and shrink deformation is severe, making them easy to break or lose conductivity, resulting in a short life.
Therefore, finding a design solution that minimizes deformation during charging and discharging is the key to designing durable fluorine batteries. Hartmann said, “In layered ionic compound materials, we predict that the process of adding and removing fluorine ions has a minimal effect on the deformation of the material structure, so a long lifetime can be achieved.”
Mishra said they are looking for a collaborator to build a prototype battery to their design and start testing.
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