In the production process of lithium batteries, coating is a crucial process. Lithium battery coating GAP refers to the size of the gap between the coating roller and the substrate during the coating process. This gap has an important impact on the uniformity and quality of the coating, and controlling the GAP of lithium battery coating is one of the keys to ensure the quality of lithium batteries.
1. Control points of coating GAP
1. Coating speed control
The coating speed affects the size of the coating GAP and needs to be adjusted according to the design of the coater and the characteristics of the slurry to ensure the uniformity of the coating.
2. Adjustment of the gap between the coating roller and the substrate
Precise control of the gap between the coating roller and the substrate to ensure the uniformity of the coating and the accuracy of the thickness.
3. Design of coating rollers
Considering the rheological parameters of the slurry, the runner cavity is calculated and simulated, as well as the flatness and straightness requirements of the upper and lower die lips.
4. Accuracy of the coating equipment
Regular maintenance and calibration are carried out to ensure the stability and reliability of the equipment.
5. Monitoring of the coating process
During the coating process, the coating GAP needs to be monitored in real time so that adjustments can be made in time to ensure the quality of the coating.
Second, the effect of coating GAP
The size of the coating GAP has a direct impact on the uniformity and quality of the coating. If the coating GAP is too large or too small, it can lead to uneven coating, affecting the performance and safety of the battery.
1. Uneven coating
Coating the GAP too much can result in uneven distribution of the slurry across the substrate, which can affect the capacity and consistency of the battery.
2. The thickness is inaccurate
Coating GAP that is too small may result in too thick or too thin coating, affecting the performance and safety of the battery.
3. Bubbles and defects
Air bubbles and defects created during the coating process can affect the performance and safety of the battery.
3. The influence of coating speed on the coating GAP of lithium batteries
In the production of lithium batteries, the coating speed is a critical process parameter that directly affects the size of the coating GAP.
1. Relationship between coating speed and coating GAP
The adjustment of the coating speed can be achieved by varying the relative speed of movement between the coating roller and the doctor. If the coating speed is too fast, the coating roller may not be able to transfer the slurry evenly to the substrate sufficiently, resulting in large gaps between the coating layers, i.e., increased coating GAP. Conversely, if the coating speed is too slow, although the coating GAP can be reduced, it may reduce production efficiency and increase production costs.
2. How to adjust the coating speed
In practice, adjusting the coating speed usually involves programming and adjusting the control system of the coating equipment. For example, the speed of the unwinding, traction and winding motors can be precisely controlled by frequency converters to accommodate different coating speed requirements. In addition, the coating thickness of each coating section can be controlled by adjusting the speed difference between the coating roller and the back roller, as well as the speed and speed curve setting of the back roller avoidance and resetting, and then the coating GAP can be indirectly controlled.
Fourth, the adjustment method of the gap between the coating roller and the substrate
1. Use a feeler gauge
Insert the feeler gauge between the two rollers and rotate the gap adjustment screw, when the feeler gauge has a feeling of contact between the two rollers, can twitch and has a slight resistance, the gap is appropriate.
2. Adjust the handwheel
If the twitching is easy, the gap is too large, so you can slowly turn it counterclockwise until you get a suitable gap. On the contrary, if the resistance is too large or cannot be pumped, it means that the gap is too small, and the handwheel can be rotated to the appropriate gap.
5. Influencing factors of coating roller clearance
1. The fluid consistency of the adhesive
The greater the fluid consistency of the adhesive, the less the thickness of the coating is transferred to the substrate.
2. Liquidity Index
The flow index also has a large influence on the thickness of the coating.
3. Coating roller speed
Increasing the speed of the coating roller will reduce the coating thickness.
6. Adjustment skills for the gap between the coating roller and the substrate
1. Adjust the gap between the left and right ends
When adjusting the gap between the coating roller and the substrate, it is necessary to pay attention to adjusting the gap between the left and right ends of the two rollers, so that the gap at the two ends is equal and the two rollers are parallel, so as to ensure uniform gluing.
2. Wing nuts and adjusting screws
The wing nut on the gearbox can be loosened, the adjusting screw can be turned to equalize the clearance, and then the wing nut can be tightened to maintain the normal position.
7. Precautions
1. Avoid direct contact
During the adjustment process, it should be ensured that there is no direct contact between the coating roller and the substrate so as not to damage the equipment or affect the coating quality.
2. Test run and fine-tuning
After adjustment, a trial run should be carried out to check whether the coating effect meets expectations, and fine-tuning should be carried out if necessary.
3. Maintenance and calibration
Regular maintenance and calibration of the coating equipment to ensure the stability and accuracy of the coating speed.
8. The importance of real-time monitoring
1. Ensure the quality of the coating
Through real-time monitoring, it can ensure that the thickness, uniformity and surface defects of the coating meet the requirements, and avoid battery performance degradation or safety hazards caused by improper coating.
2. Improve production efficiency
Real-time monitoring can help production managers understand the operation status of equipment in time, find abnormalities and faults, and take corresponding measures to repair or adjust in time to ensure the stable operation of the production line.
3. Optimize the production process
Real-time monitoring and data analysis help companies optimize production processes. It collects and analyzes production data, identifies bottlenecks and problems on the production line, and provides recommendations for improvement.
4. Quality traceability and management
Real-time monitoring and data analysis can record and trace data in the production process. It can store and manage information such as operation logs, production data, process parameters and other information of equipment, and provide traceability functions.
9. Summary
In summary, controlling the GAP of lithium battery coating is essential to ensure the quality and performance of the battery. By accurately controlling the coating speed, adjusting the gap between the coating roller and the substrate, optimizing the design of the coating roller, ensuring the accuracy of the coating equipment, and monitoring the coating process in real time, the coating quality can be effectively improved, defects and failures can be reduced, the production efficiency can be improved, and the cost can be reduced. At the same time, real-time monitoring can also help enterprises achieve quality traceability and management, and improve the reliability and safety of products. In the production process of lithium batteries, the control and real-time monitoring of the coating GAP should be highly valued.
Article source: lithium battery technology knowledge platform
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