What are the important detection methods for the thickness of lithium battery separators?

How to detect the thickness of lithium battery separator? As one of the four major raw materials for lithium batteries, separators play a pivotal role in the safety, cycle life, discharge rate and other performance of lithium batteries, but their high technical threshold has discouraged many investors. Even though lithium battery separators are now localized, there are still many technical barriers to overcome. For example: At present, almost all diaphragm thickness measurement equipment in China only has the detection function, and few can achieve the closed-loop control of the diaphragm thickness. The uniformity of the thickness of the lithium battery separator includes the uniformity of the longitudinal thickness and the uniformity of the lateral thickness, but in comparison, the lateral thickness uniformity is more important, and generally must be controlled within 1um. 1. A single frame of X-ray ensures the accuracy of online diaphragm thickness detection. The principle of online diaphragm thickness detection is to convert the attenuation of the radiation after passing through the diaphragm into diaphragm thickness. This means that the accuracy and stability of the detection must be ensured during the detection process. 2. On-line control technology of diaphragm thickness There are two important on-line control technologies for lithium battery diaphragm thickness, one is MD (longitudinal) control and CD (transverse) control; the other is diaphragm online machine vision inspection technology. 1) MD control and CD control The so-called MD control and CD control refer to the closed-loop control of the thickness in the MD direction by controlling the speed of the feeding screw or the traction speed; and the data measurement through the scanning frame, and finally the closed-loop control of the data in the CD direction. . The key technology is the CD banner alignment technology, that is, the inspection data of the scanning frame must be accurately aligned with the position of the full-width die. In addition, the shrinkage factor of the film must be considered. Only the alignment can be controlled. Great. 2) Diaphragm on-line machine vision inspection technology It is known that the key to the lithium battery diaphragm is the identification of pinholes. Energy Storage has introduced pinhole recognition technology for diaphragm detection, which is a technology to distinguish pinholes and bright spots through multi-channel imaging exposure. . In addition to pinhole recognition, it also has other intelligent classification functions, that is, intelligent classification algorithms. Through intelligent classification, comprehensive defect analysis data can be provided to help the company improve equipment and processes, and improve product quality. For the thickness test of the lithium battery separator, a non-contact thickness gauge can also be used. However, although the non-contact thickness gauge has fast measurement speed and no damage to the sample, the non-contact thickness gauge mostly uses optical principles for point measurement, and the diaphragm has a porous structure, so the measurement results fluctuate greatly. , On the contrary, it is more unfavorable for the measurement of thickness uniformity. The function of the lithium battery separator In the structure of the lithium battery, the separator is one of the key inner layer components. The performance of the diaphragm determines the interface structure and internal resistance of the lithium battery, which directly affects the battery's capacity, cycle, and safety performance. A separator with excellent performance has important uses for improving the overall performance of the battery. One is to provide safety guarantees for lithium batteries. The separator material must first have good insulation properties to prevent short-circuiting of the positive and negative electrodes or short-circuits caused by burrs, particles, and dendrites. Therefore, the separator must have a certain degree of tensile and puncture strength, and it is not easy to tear. And basically maintain the dimensional stability under sudden high temperature conditions, and will not shrink and cause large-area short circuit and thermal runaway of the battery. The second is to provide lithium batteries with microporous channels that can realize charge and discharge functions and rate performance. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete it. Previous post: Do you know the harm of lithium battery electrolyte?