Modeling NCA/C6-Si battery ageing

Abstract

The rapidly growing demand for energy storage has spurred the development of advanced Li-ion batteries. Physical-based modeling techniques have emerged as a powerful tool to assist the development of battery technologies because of the advantages of relating battery performances to internal physical and (electro)chemical processes. In the present paper, a pseudo-two-dimensional (P2D) based model has been developed for Li-ion batteries with NCA cathodes and C6/Si blended anodes. Coupled with a solid electrolyte interface (SEI) growth model and a loss of active materials (LAM) model, the P2D-based model has been applied to simulate the electrochemical behavior of pristine cells and the degradation of aged cells. For pristine cells, a competing reaction occurs between C6 and Si during (dis)charge, resulting in a sequential (de)lithiation and diverse stress behavior. For aged cells, the SEI growth mainly causes the battery capacity to fade under different cycling conditions. LAM also plays an important role in battery capacity loss. SEI growth is sensitive to the temperature, cycle time, cycle number, and cycle current, while LAM is significantly influenced by temperature and current. During storage, the main factor causing battery capacity losses is the SEI growth, which is affected by the storage time, storage state-of-charge, and temperature.