Tailoring the Morphology of LiCoO2: A First Principles Study

Surface energies of several low-index surfaces of layered LiCoO2 are investigated as a function of the external lithium and oxygen chemical potentials by means of First Principles calculations in the generalized gradient approximation (GGA) to density functional theory (DFT), treating on-site electron correlation within the DFT+U framework. We find the set of surfaces contained in the equilibrium shape to be depending on environment. The(0001)and (10 (1) over bar4) surfaces are present for all reasonable values of the Li and O chemical potentials. The (01 (1) over bar2) surface, however, is stable only under oxidizing conditions. The equilibrium shape is sensitive to the equilibration environment because the thermodynamically favorable surface terminations and surface energies of the polar (0001) and (01 (1) over bar2) surfaces are a function of environment. This provides a lever to tailor the crystal shape according to application requirements (e.g., as active material in lithium-ion batteries).