A research group, utilizing inexpensive elements, has demonstrated the feasibility of synthetic electrode materials for lithium-ion batteries (LIBs). If explored further, this method could reduce the industry’s dependence on rare metals such as cobalt and nickel.
Details of their results were published in the American Chemical Society journal ACS Applied Energy Materials on April 11, 2022.
Rare metals are widely used because they form a crystal structure suitable for the key component of LIB – the cathode material. In these materials, lithium is extracted/inserted easily and is reversible.
Scientists have long been looking for ways to incorporate other inexpensive elements into the crystal structure. However, just as a certain amount of salt dissolves in water, the solubility of other elements is also limited.
The research group, led by professor Tetsu Ichitsubo of Tohoku University’s Institute of Materials Research (IMR), used a different strategy. Utilizing the energy gain from ‘configuration entropy’ — the disordered state of the material — they expanded the solubility of the constituent elements, synthesizing electrode materials of new compositions: LiCr1/4Mn1/4Co1/4Ni1/4O2 and LiCr1/5Mn1/5Fe1/5Co1/5Ni1/ 5O2. This significantly reduces the use of cobalt and nickel.
“Our approach unlocks the potential of other unused elements and will allow us to simultaneously optimize multiple electrode properties thanks to the flexible material design,” said Ichitsubo.
Materials synthesized by the new method can also increase the safety of LIB. Tomoya Kawaguchi, assistant professor at IMR and corresponding author of the paper states, “Increasing the entropy of the configuration also theoretically improves the stabilization of the electrode material, contributing to the safety of the entire battery.”
Ichitsubo and his group also clarified the degradation mechanisms that affect battery cycles with this new material. This will serve as a guideline for developing new high-performance materials using a high-entropy strategy.
While the cyclability and capacity are not matched by current conventional LIBs, the ability to synthesize new electrode materials opens further avenues for LIB research.
Materials provided by Tohoku University. Note: Content can be edited for style and length.
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