A New Polymorph of Layered LiCoO2

Abstract A new polymorph of layered LiCoO2 was prepared from OP4-LixNayCoO2 by ion exchange. Structural analysis by synchrotron X-ray diffraction revealed that the new polymorph of LiCoO2 is O4-type LiCoO2 whose structure corresponds to intergrowth of O2- and O3-type LiCoO2. It was also confirmed that the O4-type LiCoO2 shows electrochemical activity and different reversible voltage in aprotic lithium cells in comparison to those of O2- and O3-type LiCoO2, which are well-known electrode materials as polymorphs of LiCoO2.