Thermodynamic modeling of the LiCoO2–CoO2 pseudo-binary system

The thermodynamic modeling of the LiCoO2–CoO2 pseudo-binary system, a positive electrode material of Li-ion batteries, was performed using the CALPHAD technique. The O3-LiCoO2 and the O1-CoO2 phases were described using the four-sublattice model with the formula (Li,V a)1/2(Li,V a)1/2(Co)1(O)2, and the three-sublattice model with the formula (Li,V a)1(Co)1(O)2. The H1_3 hybrid phase was treated as a non-stoichiometric compound. The thermodynamic quantities, such as the phase equilibria, formation enthalpies and cell voltage (vs. Li/Li+), were in agreement with data reported in the literature.