Multi-scale swelling behaviors and mechanisms of graphite electrode-based lithium-ion battery at various charging rates

The swelling of lithium-ion batteries is a crucial mechanical behavior that can have a significant impact on battery safety and performance, and it also serves as an indicator of the battery's state of charge and overall condition. With the development of fast charging technology, the range of battery charging rates (C-rates) has increased. In recent studies, some experimental results have shown that the C-rate clearly affects the swelling behavior of LIBs. However, the existing models ignore the impact of the C-rate due to a lack of mechanism analysis. To bridge this gap, we developed a multi-scale model to reveal the distinct multi-scale swelling behaviors and mechanisms at various C-rates based on graphite electrode-based LIBs. First, we conducted experiments on the swelling displacement and swelling force of pouch-type batteries at various C-rates. Then, a multi-scale model is developed to reveal the underlying mechanisms responsible for the differences in the behavior of battery swelling at various C-rates. Finally, a simplified model for lithium intercalation swelling at various C-rates is established. The results of this study contribute to the understanding of the swelling behavior of graphite electrode lithium-ion batteries and to the design, application, and safety performance monitoring of these batteries.