Process Control Measures for Poor Self-Discharge of Lithium-Ion Batteries
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 batter-ies,formulates improvement measures from the aspects of raw material end,process control and self-dis-charge 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 0.5 μm 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 lamina-tion and ultrasonic welding,which can effectively reduce the probability of self-discharge.The final self-dis-charge 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%.