LiCoO₂ is one of the most widely commercialized cathode materials for Li-ion batteries. Recently, LiCoO₂ has been revisited to improve its reversible capacity by increasing the upper cut-off voltage to 4.55 V (vs. Li/Li⁺). However, LiCoO₂ suffers from determental Co-dissolution and electrolyte decomposition at high voltages and high temperatures, resulting in poor electrochemical performance.[1,2] In this connection, various coated LiCoO₂ powders have been investigated to reduce these irreversible surface reactions.[3]

Coated LiCoO₂ powders are usually obtained via sol-gel synthesis, dry coating, and atomic layer deposition. These coating techniques are pursuing to uniform coating covering the whole surface of LiCoO₂ powders. However, the full coverage of coating layers interrupts the charge-transfer of Li⁺ ions, resulting in the poor rate capability of LiCoO₂. This implies that we can improve the rate performance of LiCoO₂, if we are able to coat specific facets of LiCoO₂ powders except for the charge-transfer planes.

In this presentation, we introduce, for the first time, a new plane-selective coating of LiCoO₂. For example, we demonstrate that metal oxides coating layers are grown plane-selectively on the LiCoO₂(001) surface. We show synthesis details for the plane-selective coating of LiCoO₂. Scanning transmission electron microscopy (STEM) analysis was carried out with a high-angle annual dark field (HAADF) mode to observe the plane-selective coatings. The electrochemical performance of the plane-selectively coated LiCoO₂ was better than that of the conventionally coated LiCoO₂. Moreover, we discuss the origin of the plane-selective coating of LiCoO₂.

References

[1] B. Xu, D. Qian, Z. Wang, Y. S. Meng, Materials Science and Engineering: R: Reports 2012, 73, 51

[2] W. Li, A. Dolocan, P. Oh, H. Celio, S. Park, J. Cho, A. Manthiram, Nat Commun 2017, 8, 14589

[3] Y.-K. Sun, C. S. Yoon, S.-T. Myung, I. Belharouak, K. Amine, Journal of The Electrochemical Society 2009, 156, A1005