Precision in Every Layer: Capacitive Sensors for Flawless Battery Film Production
Battery films must be produced with an exact thickness and uniform coating, as even slight deviations can affect the performance and safety of the subsequent energy storage system. Capacitive sensors from Micro-Epsilon enable non-contact, high-resolution and fast detection of layer thicknesses and material properties. This makes them an important part of process monitoring and quality assurance in battery film production.
With the growing global demand for high-performance energy storage systems, the production of battery films is becoming increasingly important. A key development trend is the production of ever thinner films with a higher energy density, improved conductivity and better heat dissipation. However, the reduction in film thickness also places increased demands on the production processes: even the smallest deviations in film thickness or coating homogeneity can significantly impair the performance, service life or safety of a battery.
High accuracy and stability for demanding production processes
This is where capacitive sensors from Micro-Epsilon come into play. With their sub-nanometer resolution and high frequency response in the kHz range, they are ideal for high precision and dynamic measurement tasks in battery film production.
A major advantage is the independence from the ambient conditions. Due to their innovative technology, capacitive sensors from Micro-Epsilon are able to deliver reliable and high precision measurement values even at high temperatures. They are therefore ideal for demanding industrial environments. These sensors also offer excellent temperature stability, so that even fluctuating ambient temperatures are not a problem. This is particularly important as many process steps – such as calendering or coating – are associated with high thermal loads.
Another strength is the combination variety. Each capacitive sensor can be operated with any Micro-Epsilon controller without requiring any complex calibration. The manufacturer offers the world’s most modern product portfolio of capacitive sensors with over 40 standard models.
It is also possible to adapt the sensors to special requirements at any time. Modern interfaces such as Ethernet, EtherCAT and PROFINET ensure quick and easy connection to existing systems. Capacitive sensors can be used not only to measure distance, but also thickness and roller gap, which is why they are used in various process steps in battery film production.
Thickness measurement of coatings before calendering
The combiSENSOR KSB6430 is specially designed for one-sided thickness measurement of electrode coatings. The sensor system detects material thicknesses from 5 µm to 3 mm with sub-micrometer accuracy. The combiSENSOR KSB6430 combines two methods: a capacitive sensor for detecting the distance to the film coating and an eddy current sensor that measures the distance to the chrome-coated steel roller, which serves as a reference target. The difference between the two signals is used to precisely calculate the thickness value of the coating, with mechanical influences being automatically compensated for. The non-contact measurement takes places from one side and directly during the production process. The sensor system is insensitive to dirt and offers high temperature stability. Operation is possible in a temperature range from -10 °C to +180 °C, which also allows operation close to the calender.
Inline thickness measurement of battery films
The capaNCDT 6200 modular multi-channel measuring system is used for the inline thickness measurement of battery films with and without coating. This allows several sensors to be operated simultaneously, which are mounted opposite each other using a compact mounting bracket and precisely aligned on one axis. The controller calculates the exact thickness measurement value of the battery film from the linear distance signals of two sensors arranged opposite each other. Up to six sensors can be attached to one mounting bracket so that up to three simultaneous measurements can be taken at different points. The bracket is extremely temperature-stable at temperatures of up to 100 °C and is therefore specially designed for the requirements of the battery industry. The measurement spot of the sensors is larger than that of optical methods, which is why surface structures and anomalies can be averaged.
Offline thickness measurement of battery films
Another system for high precision thickness measurements is the capaNCDT TFG6220, which is used for quality testing in the form of offline random samples. The TFG6220 is pre-assembled ready for rapid deployment. The thickness is measured by two opposing capacitive sensors whose signals are offset against each other. A measuring insert serves as a flat reference and support surface over which the measuring object is clamped. A vacuum device sucks in the film and thus ensures wrinkle-free support without damaging the object to be measured. In this way, the thickness measurement is highly reproducible. The TFG6220 consists of a measuring bracket including sensors and an external controller unit. The intuitive web interface can be used to make settings, perform measurements and display and output the measured data.
Precise control of the roller gap
Battery films are compacted and smoothed in coating lines using calendering technology. Two adjustable rolls ensure that the material mixture is rolled to the specified thickness. The capaNCDT CSG capacitive flat sensors are used for gap monitoring and control of the calender and coating rollers. These are available in various designs and detect the roller gap with micrometer accuracy. The compact sensors can be integrated into confined installation spaces to measure directly against the rollers or the roller suspension. Direct gap measurement is possible via integration on the roller, for example with a flat sensor just 0.9 mm thick. The sensor measures on both sides and therefore detects two distances. The roller gap is controlled during operation based on the measured values. In addition, the temperature-stable design allows use even at high ambient temperatures. To protect the sensor from dust deposits, an air purge device is integrated. Another option is indirect gap measurement via integration on the shaft using an extremely compact 4 x 3.5 mm capacitive sensor.
Precise measurement of the bearing gap
A second application on calender rolls is the determination of roll wear which is measured indirectly via the change in the bearing gap of the drive shaft. The capaNCDT sensors measure continuously and with high precision. As a result, wear is permanently determined and detected at an early stage, which means that maintenance intervals can be scheduled in a targeted manner. The capacitive sensors can also be used with strong temperature fluctuations and provide a high signal stability.
Conclusion
Capacitive sensors from Micro-Epsilon play an important role in quality control and process monitoring in battery film production. They help to ensure the homogeneity of the films, detect deviations at an early stage and minimize rejects. They therefore make a decisive contribution to increasing the efficiency of battery film production and meeting the high demands placed on modern energy storage systems.
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Captions:
Author:
Michael Kuran – LinkedIn
Battery Industry Manager
MICRO-EPSILON MESSTECHNIK GmbH & Co KG
Königbacher Str. 15 | 94496 Ortenburg | Germany
Phone: +49 8542 168-0
battery@micro-epsilon.com
www.micro-epsilon.com
