Graphical abstract. Credit: ACS Applied Energy Materials (2022). DOI: 10.1021/acsaem.1c03968
A research team has proved the capability of producing electrode materials for lithium-ion batteries by exploiting cheap components (LIBs). If this approach is investigated further, it has the potential to lessen industrial dependency on rare metals such as cobalt and nickel.
Rare metals are commonly employed in LIBs because they have a crystal structure that is suited for the cathode materials, which are the essential component of the device. Lithium can be readily and reversibly removed from and introduced into these materials.
Scientists have been looking for methods to add other low-cost elements into the crystal structure for a long time. In spite of this, just as only a certain quantity of salt can dissolve into water, the solubility of other elements is also restricted.
Professor Tetsu Ichitsubo, director of Tohoku University’s Institute for Materials Study (IMR), led a team of researchers that took a fresh approach to their research problem. Using the energy gain from “configurational entropy,” or a material’s state of randomness, they were able to increase the solubility of the constituent elements, resulting in the creation of new composition electrode materials, such as LiCr1/4Mn1/4Co1/4Ni1/4O2 and LiCr1/5Mn1/5Fe1/5Co1/5Ni1/5O2 and LiCr1/5Mn1/5Fe1/5Co1/5N This resulted in a considerable reduction in the consumption of cobalt and nickel.
In addition, “our technique opens the potential of additional hitherto untapped components and will enable us to improve several electrode characteristics at the same time, due to our flexible material designs,” adds Ichitsubo.
The materials produced by the new approach may also have the potential to increase the safety of LIBs. “Increasing configurational entropy also theoretically increases the stability of the electrode material, adding to the overall safety of the battery,” says Tomoya Kawaguchi, associate professor at IMR and corresponding author of the work.
Using these novel materials, Ichitsubo and his team were able to better understand the degradation mechanisms that impact the battery cycle. When employing the high-entropy technique to design unique high-performance materials, the results of this study will serve as a guideline.
While the cyclability and capacity of the novel electrode materials did not equal those of traditional LIBs at this time, the ability to synthesis new electrode materials opens up new paths for study into LIBs in the future.
Further information: Tomoya Kawaguchi et al, Influences of Enhanced Entropy in Layered Rocksalt Oxide Cathodes for Lithium-Ion Batteries, ACS Applied Energy Materials (2022). DOI: 10.1021/acsaem.1c03968