Abstract
Lithium cobalt oxide (LCO) cathode is one of the most commonly used positive active materials for lithium ion batteries (LIBs). However, one reliability issue that limits its applications is the presence of moisture adsorbing on the LCO cathode surface, which may react with the electrolyte and lead to detrimental effects. In this study, a novel LCO thin film cathode is proposed, by adding a layer of high diffusion resistant (003) phase of LCO as the protective coating onto the diffusion favorable (110) phase, in order to simultaneously achieve good electrochemical performance and chemical stability of the LIB. A multi-physics-based finite element model is built to investigate the performance of the cathode and the influences of the design and operation variables, including the layout the two crystal phases, the fraction of each phase and the lithiation C rate. In addition, a Gaussian Process based surrogate model is developed, using the simulated results from the FE model as training data, to efficiently explore the design space of the cathode. It is found that, the 110//003 layout cathode could provide high capacity and good rate performance; meanwhile, the 003//110 design may lead to a largely reduced capacity, especially at high lithiation C rates.
