A Membrane Preparation Method Based on Oil Content Feedback Process

Abstract

A film preparation method based on an oil content feedback process, comprising mixing and heating polyethylene, paraffin oil, silica nanoparticles, and 4,4'-thiobis(6-tert-butyl-m-cresol) in batches, and Extrusion molding, after transverse stretching and longitudinal stretching, and then two-dimensional stretching. After stretching, the film is sent to the oil content analysis device, and the oil removal device is optimized and controlled according to the distribution of oil stains on the oil absorbing material, so as to finally obtain a lithium battery separator with low oil content.

Description

technical field [0001] The invention relates to the technical field of lithium battery diaphragm and its preparation. Background technique [0002] Separator is an important part of lithium battery, which directly determines the performance and safety of lithium battery. Usually the diaphragm is an insulating material with a porous structure. For the separator, it is usually necessary to ensure a certain porosity and opening size, so that ions can migrate smoothly. If it is too high, the strength of the diaphragm will decrease, and if it is too low, the internal resistance will increase. The uniformity of the membrane also affects the electrolyte wetting the membrane, thereby affecting the internal resistance of the battery. Moreover, under abnormal conditions, too much current will cause the temperature to rise to T1, thereby closing the pores of the membrane, thereby stopping ion migration and avoiding further danger. But if the temperature rises too high to T2, it wil...

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Problems solved by technology

But this is time-consuming and labor-intensive, and multi-parameter crossover is difficult to control

At the same time, they did not realize that the consistency of the comprehensive performance of each parameter is of great significance to battery safety and performance improvement.

[0005] However, if a method that can comprehensively characterize each parameter is selected for process control, the control accuracy of the process will be higher, and there is no mention in the prior art of how to use a simple method to realize the process control of this composite parameter

[0006] In addition, grease or other solvents are inevitably used in the preparation process of the film. Although it will be extracted during the process, there may still be a small amount of residue. Whether the grease is extracted cleanly has a great impact on the performance parameters of the film.

If the oil is not extracted, it will directly affect the porosity and air permeability of the separator, and then affect the internal resistance and cycle performance of the battery.

The existing oil content detection method is usually a destructive test, which is not only complicated to operate, but also cannot be applied to the online feedback of the production line, and cannot be directly used to optimize the production process, and can only be used as the test result of the final product

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