锂离子电池自放电不良的过程管控措施

Process Control Measures for Poor Self-Discharge of Lithium-Ion Batteries

锂离子电池自放电不良问题作为困扰行业多年的一大难题,也是很多锂离子电池发生安全事故的直接原因。本文结合商品化锂离子电池生产过程中的关键控制点,从原材料端、制程管控以及自放电筛选方式等方面制定改善措施。控制负极石墨中磁性异物含量在0.0001%以下,涂布头洁净度为0.5μm粉尘粒子数小于5000/2.83 L,负极片黏结力提升至0.3 N/25 mm以上,明确叠片、超声波焊接等工序粉尘、金属异物的清洁要求及频次,可有效降低自放电发生的概率。最终自放电筛选结果表明,以上措施实施后,批量生产的锂离子电池自放电不良率降低至0.2%以下。

As a major problem that has plagued the industry for many years,the problem of poor self-discharge of lithium-ion batteries is also the direct cause of many safety accidents of lithium-ion batteries.This paper combines with the key control points in the production process of commercial lithium-ion batteries,formulates improvement measures from the aspects of raw material end,process control and self-discharge screening methods.By controlling the magnetic foreign matter content of the negative electrode graphite to be less than 0.0001%,the coating head cleanliness of 0.5μm dust particles number to be less than 5000/2.83 L,improving the adhesion of the negative electrode sheet to be more than 0.3 N/25 mm,and clarifying the cleaning requirements and frequency of dust and metal foreign matter in the process of lamination and ultrasonic welding,which can effectively reduce the probability of self-discharge.The final self-discharge screening results show that after the implementation of the above measures,the self-discharge defect rate of mass-produced lithium-ion batteries decreases to below 0.2%.