First—Principles Studies Of Delithiation Of LiCoO₂for Lithium Ion Batteries

The first-principles PAW pseudopotential method within the generalized gradient approximation(GGA) based on the density functional theory(DFT) is employed to investigate mainly bulk phase LiCoO2behavior of delithium from the following three questions.1. The geometry and electronic structure of the bulk cathode material LiCoO2have been studied by simulate calculations. Firstly we use Vasp program package to optimize its structure in order to get more accurate lattice constant. The research mainly strart from the geometric structure and electronic structure and the structure density of states and partial density of states has been shown. our calculations are in good agreement with experimental datas and other theoretical results. It shows the PAW+GGA method will be justifed.2. Production delithiated LixCoO2:Lio.75Co02、Li0.5Co02and Li0.25Co02have been studies in details. Meanwhile,The total density of states and partial density of states have also been studied in details. The results suggest that structures are stable during lithium deintercalation.3. The first-principle calculations based on the denstiy functional theory also employed to investigate the delithiated LixCoO2with oxygen vacancy have been studied in details. The result show that oxygen vacancy is one important reason to the structural instability. We found that spin flip occurs to the electronic structure of Co-3d close to oxygen vacancies.