We therefore construct a Ti-rich doped CoO2 model system, where 1/3 of Co ions in one TM layer are substituted by Ti ions and each Ti ion is surrounded by six Co ions (Figure ), to investigate the Ti dopant's impact on the kinetic barriers of the Co migrations and the correlated oxygen dimer formation. The reason for choosing the Ti dopant is that the most common valence state of the Ti ion is 4+, matching the Co ions' valence state in the CoO2 system, the magnetic moments of Co ions thus would not be affected upon introducing Ti dopants into the model. We employ DFT+U calculations combined with the CI-NEB method to compute the barriers of the key steps involving Co migrations and oxygen dimer formation (computational details can be found in SI).