锂电池极片辊压过程力学行为与结构
Mechanical behavior and structure of lithium-ion battery electrode calendering process
谢欣兵 1杨凯悦 1杜晓钟2
作者信息
- 1. 太原科技大学机械工程学院,山西 太原 030024
- 2. 太原科技大学机械工程学院,山西 太原 030024;太原科技大学能源与材料工程学院,山西 太原 030024
- 折叠
摘要
辊压是锂离子电池极片制备过程中的关键步骤,其结果将会影响电池的一致性和安全性.极片作为一种由集流体(金属)和涂层(非金属)组成的复合材料,无疑增加了辊压变形机理的复杂性.本研究采用离散元(DEM)模型表征锂电池正极片涂层部分,对极片辊压过程进行了数值模拟;制备了锂电池正极片,并完成了不同程度压下的辊压实验.辊压数值模拟结果与实验观测结果展现了较好的一致性,验证了模型的准确性,分析了整个辊压过程极片的形貌演变,揭示了辊压变形的实质,获得了辊压过程涂层与集流体结合界面处的载荷,并对界面结合处进行了深入分析.结果表明:DEM模型模拟可以获得极片微结构演化过程和真实力学行为;随着辊压压下量的不断增加,集流体所受最大应力呈线性上升趋势;涂层部分活性颗粒间紧密度明显增加是辊压变形的根本原因;部分涂层活性颗粒嵌入集流体表面,使集流体产生明显的塑性变形,并伴有应力集中现象.为进一步探索极片辊压过程提供了研究思路和有价值的见解.
Abstract
Calendering is a crucial step in the electrode preparation process for lithium-ion batteries,significantly impacting the battery's consistency and safety.Given that the electrode is a composite material comprising a current collector(metal)and a coating(nonmetal),the complexity of the calendering deformation mechanism is heightened.In this study,we employed the discrete element method(DEM)model to characterize the coating component of the cathode electrode in a lithium battery,simulating the electrode calendering process numerically.Cathode electrodes were prepared,and experiments with varying calendering degrees were conducted.The congruence between the numerical simulations and experimental outcomes validates the model's accuracy.This research delves into the electrode's morphological evolution throughout the calendering process,unveiling the fundamental nature of calendering deformation.It also quantifies the load at the interface between the coating and the current collector during calendering,providing an in-depth interface analysis.The findings indicate that the DEM model can effectively simulate the microstructural evolution and actual mechanical behavior of the electrode.As the rolling reduction increases,the maximum stress on the current collector exhibits a linear rising trend.The enhanced compactness among the active particles in the coating is identified as the primary cause of calendering deformation.Some active particles in the coating become embedded in the current collector's surface,causing noticeable plastic deformation and stress concentration.This investigation offers innovative research perspectives and valuable insights for further exploration of the electrode calendering process.
关键词
锂电池/极片辊压/离散元法Key words
lithium-ion battery/electrode calendaring/discrete element method引用本文复制引用
基金项目
山西省自然科学基金(202103021224273)
山西省国家留学基金(2021137)
出版年
2024
国家科技期刊平台
NSTL
万方数据