动力锂离子电池极片的辊压工艺研究

摘要

The uniformity of electrodes thickness is one of the most important factors that affect the capacity,cycle life and safety of lithium ion battery.Aiming at inferior thickness uniformity and narrow rolling width,the finite element models of the two-high mill and the four-high mill are established,and the accuracy of the finite element model is verified by experiments.The four-high mill rolls system model which is equivalent to the two-high mill φ 500×500 in the same rolling condition is also established,and the influence law of the change of working roll diameter,supporting roll diameter,roll length of four-high mill and bending force on the electrodes thickness uniformity is analyzed.The results show that,the four-high mill instead of two-high mill has the feasibility of rolling power lithium ion battery electrodes.With the increase of four-high mill working roll diameter and supporting roll diameter,electrodes thickness uniformity along the width direction is improved.With the increase of four-high mill roll length,electrodes thickness uniformity along the width direction is decreased.With the increase of working roll bending force,electrodes thickness uniformity along the width direction and rolling width are improved,it can improve the problem that electrodes rolling width is too narrow in actual production.%极片的厚度一致性对动力锂离子电池组的容量、循环寿命和安全性等有重要的影响.针对极片在实际辊压中存在厚度一致性差和辊压宽度窄的问题,采用有限元软件建立了二辊辊压机和四辊辊压机的轧辊有限元模型,借助实验的方法验证了所建有限元模型的准确性.得到了相同辊压工艺条件下与二辊辊压机φ500×500等效的四辊辊压机辊系模型;分析了四辊辊压机工作辊辊径、支撑辊辊径、辊身长度及弯辊力的变化对极片厚度一致性的影响规律.研究结果表明:四辊辊压机代替二辊辊压机辊压动力锂离子电池极片具有可行性;随着四辊辊压机工作辊辊径和支承辊辊径的增加,极片沿宽度方向的厚度一致性有所提高;随着四辊辊压机辊身长度的增加,极片沿宽度方向的厚度一致性变差;随着对工作辊施加弯辊力的增加,极片沿宽度方向的厚度一致性提高,同时极片辊压宽度也有所增加,可以改善目前实际生产中极片辊压宽度过窄的问题.