Electronic phase diagram of Li${}_x$CoO${}_2$ has been reexamined using potentiostatically de-intercalated single-crystal samples. Stable phases of $x\sim 0.87$, 0.72, 0.53, 0.50, 0.43, and 0.33 were found and isolated for physical property studies. A-type and chain-type antiferromagnetic orderings have been suggested from magnetic susceptibility measurement results in $x\sim 0.87$ and 0.50 below approximately 10 and 200 K, respectively, similar to those found in Na${}_x$CoO${}_2$ system. There is no Li vacancy superlattice ordering observed at room temperature for the electronically stable phase Li${}_{0.72}$CoO${}_2$ as revealed by synchrotron x-ray Laue diffraction. The peculiar magnetic anomaly near $\sim$175 K as often found in powder samples of $x\sim 0.46$–0.78 cannot be isolated through this single-crystal potentiostatic method, which supports the previously proposed explanation to be a surface stabilized phase of significant thermal hysteresis and aging character.

• Received 5 August 2011

DOI:https://doi.org/10.1103/PhysRevB.85.035120