Researchers develop LiMn2O4 cathode material with both high power rate performance and long cycle life
A research team from Korea Advanced Institute of Science and Technology (KAIST), Korea Electronics Technology Institute (KETI), and Tokyo Institute of Technology has developed a truncated octahedral structure for LiMn2O4 that enables both high power rate performance and long cycle life in a Li-ion cathode material.
Spinel-structured lithium manganese oxide (LiMn2O4) cathodes have been successfully commercialized for various lithium battery applications and are among the strongest candidates for emerging large-scale applications. Despite its various advantages including high power capability, however, LiMn2O4 chronically suffers from limited cycle life, originating from well-known Mn dissolution.
An ironical feature with the Mn dissolution is that the surface orientations supporting Li diffusion and thus the power performance are especially vulnerable to the Mn dissolution, making both high power and long lifetime very difficult to achieve simultaneously.—Kim et al.
|Rate capability tests measured at various C-rates for discharge. Credit: ACS, Kim et al. Click to enlarge.|
In a paper in the ACS journal Nano Letters, the team reports the development of a truncated octahedral structure in which most surfaces are aligned to the crystalline orientations with minimal Mn dissolution, while a small portion of the structure is truncated along the orientations to support Li diffusion and thus facilitate high discharge rate capabilities.
When compared to control structures with much smaller dimensions, the truncated octahedral structure exhibited better performance in both discharge rate performance and cycle life.
...a series of results implicate that key electrochemical properties of LiMn2O4 are considerably dependent on its surface orientation. Our design concept of truncating a small portion of surfaces to support Li diffusion while leaving most remaining surfaces aligned along the crystalline orientations with minimal Mn dissolution enables excellent rate performance and cycle life simultaneously. The results suggest an ideal electrode structure of LiMn2O4, which is one of the most viable options for emerging large-scale battery cathodes.—Kim et al.
Joo-Seong Kim, KyungSu Kim, Woosuk Cho, Weon Ho Shin, Ryoji Kanno, and Jang Wook Choi (2012) A Truncated Manganese Spinel Cathode for Excellent Power and Lifetime in Lithium-Ion Batteries. Nano Letters doi: 10.1021/nl303619s