It is widely known that lithium-ion batteries (LIBs) degrade and lose performance during usage. Accurately predicting LIB aging is essential for optimizing design and usage, and enabling second-life applications and recycling.
The main causes of LIBs performance decay are mechanical and electrochemical degradations. During battery operation, lithium ions (de)intercalate into the active material particles constituting the microstructure of electrodes. Areas with higher lithium content deform more than those with lower lithium content, causing differential deformation and diffusion-induced stress. Furthermore, electrochemical side reactions, such as the solid electrolyte interface (SEI) growth, continuously consume lithium ions. These mechanisms lead to capacity fade, resistance increase, and irreversible battery swelling, which is often overlooked in the literature.
This work presents POLIDEMO, an innovative LIB degradation model that addresses the limitations of traditional physics-based models by significantly reducing the simulation time, improving the accuracy in the estimation of the model parameters, and enhancing the representation of the degradation mechanisms. The key strength of POLIDEMO is the prediction of the knee point in the capacity fade curve and the irreversible swelling, which is highly relevant to the mechanical behavior of the battery pack.
The model is general and it is validated using aging tests performed on various LIBs chemistries under different operating conditions. Thus, POLIDEMO is a valuable tool that enhances LIBs lifetime modelling in both academic and industrial contexts.