Thermodynamic modeling of the LiCoO2–CoO2 pseudo-binary system

Abstract The thermodynamic modeling of the LiCoO 2 –CoO 2 pseudo-binary system, a positive electrode material of Li-ion batteries, was performed using the CALPHAD technique. The O3-LiCoO 2 and the O1-CoO 2 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.