Causes And Controls of Dark Marks on Lithium Battery Coatings

In response to the causes and control issues raised by friends about the dark marks on lithium battery coatings, this article will deeply explore the reasons for the dark marks appearing after drying of lithium battery coatings for your reference, and discuss the corresponding control methods. Dark marks are a common problem during the coating process of lithium batteries and can affect battery performance and quality. By analyzing all aspects of the coating process, multiple factors such as the viscosity of the slurry, coating speed, heating temperature, and knife edge conditions all affect the occurrence of dark marks to find out the causes; in order to reduce the occurrence of dark marks, it is proposed how to Control these factors to reduce the appearance of dark marks。

I. Introduction

Dark marks are prone to occur during the coating and drying process of lithium batteries, which not only affects the appearance quality of the battery, but may also have a negative impact on the performance of the battery. Below we will discuss the causes and control methods of dark marks after drying of lithium batteries. .

2. Lithium battery coating and drying process

The coating and drying process of lithium batteries includes evenly coating the uniformly stirred slurry on the current collector and drying the organic solvent in the slurry. In this process, coating consistency, slurry viscosity, drying temperature and time are all key factors.

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3. Causes of dark marks

1. Changes in slurry viscosity

The viscosity of the slurry has an important influence on the uniformity of coating. If the slurry viscosity is unstable, it may result in uneven coating thickness, resulting in dark marks.

2. Changes in coating speed

Unstable coating speed will affect the coating effect of the slurry on the current collector. Too fast or too slow speed may lead to the appearance of dark marks.

3. Effect of heating temperature

Insufficient or too high heating temperature will affect the removal of solvent in the slurry and the crystallization of the binder, which will lead to problems such as dark marks and active material peeling.

4. Knife edge condition

Foreign matter on the knife edge or uneven surface will cause uneven thickness on the surface of the pole piece, resulting in linear dark marks.

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4. Control points of dark mark problem

1. Ensure coating consistency

Pay close attention to changes in slurry viscosity and adjust process parameters in a timely manner to ensure the stability of the slurry. It is necessary to pay attention to the changes in the liquid level on the hopper to ensure the stability of the coating speed.

2. Control the drying process

Set the drying temperature and time reasonably to fully remove the solvent in the slurry and avoid binder crystallization caused by excessive temperature. In addition, regularly inspect and maintain the oven equipment to ensure its normal operation.

3. Optimize coating process

To address the problem of difficulty in adjusting the coating thickness, the accuracy and consistency of coating can be improved by improving the design of the coating machine or using more advanced coating technology.

4. Strengthen quality inspection

Conduct three inspections before coating and drying, including inspection of thickness, quality and size. Regularly check the corresponding pulping speed, baking time, gap and other parameters to ensure the stability of the process and the quality of the product.

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5. Conclusion

The occurrence of dark marks after lithium battery coating is dried is mainly related to factors such as slurry viscosity, coating speed, heating temperature, and knife edge conditions. By strictly controlling these factors, the appearance of dark marks can be effectively reduced and the quality and performance of lithium batteries can be improved. Regular quality inspections and equipment maintenance are also important measures to ensure the stability of the coating process.