关键词: 电动汽车, 动力电池, 电化学模型, 负极析锂

Abstract: Fast charging is an inevitable demand for the rapid development of lithium-ion batteries. However, during the fast charging process, when lithium ions fails to intercalate promptly into the graphite anode, it is easy to experience “lithium plating”, which seriously affects its durability and safety. Lithium plating online detection is a necessary means to improve the safety of fast charging batteries. Therefore, this paper selects 5 solid liquid particle points to characterize the potential distribution and simplify the P2D electrochemical model based on the porous electrode theory of batteries. The diffusion process of lithium ions in the solid phase particles and liquid phase inside the battery is discretized and solved separately. Lithium plating is evaluated based on the potential difference between the solid and liquid phases on the negative electrode surface. Qualitative analysis of lithium plating is carried out through scanning electron microscopy microscopic morphology observation and energy spectrum analysis. It is proposed to use the product of the peak appearance time and peak height of the relaxation voltage differential curve after charging as the validation parameter for indirect quantitative verification of the estimated lithium evolution amount. The model validation results under different temperature and magnification conditions indicate that the estimation error of the validation parameters for lithium plating in this model is less than 15%, which can achieve rapid plating of lithium evolution in lithium-ion batteries.

Key words: electric vehicle（EV）, lithium battery, electrochemical model, lithium plating