Researchers from China and the US have developed a cobalt-free, Li- and Mn-rich (LMR) Li-ion battery cathode with negligible voltage decay. The new development overcomes the persistent challenge of voltage decay with LMR layered oxides and could lead to significantly higher energy storage capacity. A paper on their work is published in the journal Nature Energy.

LMR layered oxides are a promising class of cathodes for LiBs due to their high capacity and low cost. However, a long-standing problem of voltage decay hinders their application.

The researchers’ approach focused on stabilizing the honeycomb structure at the atomic level. By incorporating additional transition metal ions into the cathode material, the team reinforced the honeycomb structure, resulting in a negligible voltage decay of only 0.02 mV per cycle, the first time that LMR cathode material with such a low level of voltage decay has been reported.

The material has a composite structure consisting of layered LiTMO₂ and various stacked Li₂MnO₃ components, where transition metal (TM) ions that reside in the Li layers of Li₂MnO₃ form caps to strengthen the stability of the honeycomb structure. This capped-honeycomb structure is persistent after high-voltage cycling and prevents TM migration and oxygen loss as shown by experimental and computational results.

—Luo et al.

Through advanced atomic-scale measurements and calculations, the team found that these interlayer transition metal ions act as a cap above or below the honeycomb structure, preventing cation migration and maintaining stability. The structure remained intact even at high cut-off voltages and throughout cycling, ensuring the batteries’ structural integrity.

These findings are promising for various applications, from powering electric vehicles to portable electronics. The next step involves scaling up the manufacturing process for large-scale battery production.

Resources

• Luo, D., Zhu, H., Xia, Y. et al. (2023) “A Li-rich layered oxide cathode with negligible voltage decay.” Nat Energy doi: 10.1038/s41560-023-01289-6