Modern battery technologies play a central role in numerous fields of application, from electric vehicles and energy storage systems, to mobile devices such as smartphones. With the increasing focus on sustainability and electrification, the importance of batteries continues to grow. A high-precision production process is essential to meet this demand and to keep the quality, performance and cost-effectiveness of batteries at the highest level. State-of-the-art sensor technology from Micro-Epsilon is used to optimize the individual production processes and maximize quality.
Sensor specialist Micro-Epsilon offers high-precision solutions for numerous applications in battery production. These range from individual sensors to complete sensor systems, from inline thickness measurement and precise machine monitoring, to 3D surface inspection. The sensors are used by leading battery manufacturers and automotive groups around the world and impress with their high precision and reliability. The manufacturer offers quality and solutions expertise for both series and OEM applications. The sensor signals can be calculated, evaluated or analyzed using turnkey solutions.
More precision in battery production
Sensors and systems from Micro-Epsilon are used in highly automated processes in all production steps of anodes and cathodes, separators and active material. They measure with high precision during coating, calendering, assembly and even forming. Micro-Epsilon offers numerous solutions for electrode film coating lines in particular. The sensor systems are used for both wet and dry coating processes. Coated copper film can be monitored in the same way as aluminum film. Process-critical parameters are the coating thickness, thickness of the films, web edge position and coil unwinding, as well as the monitoring of the coating application at the edges.
Thickness measurement of battery film
Optical sensors such as capacitive sensors have proven themselves in inline thickness measurement of battery film. These have a larger measuring spot, which means an inhomogeneous structure can be compensated for via the area integration of the sensor. In addition, the capacitive sensors can also be used at high process temperatures of up to 200°C. Thanks to integrated temperature compensation, they deliver stable measurement values in the sub-micrometer range. Capacitive sensor technology was previously used primarily in the semiconductor industry for clean room applications. After further innovative development and adaptation to industry requirements, they now set a new standard in distance and thickness measurement tasks across the entire process chain.
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In addition to capacitive sensors, confocal chromatic sensors, white light interferometers and laser sensors are also used. These are typically used to monitor and control wet coating processes, but are also suitable for dry processes.
Two-sided thickness measurement for electrode coating
With double-sided thickness measurement, two sensors from the optoNCDT 1900 LL series are arranged opposite each other, each one measuring the distance to the battery film. Based on synchronization combined with the precise sensor alignment, high measurement accuracy and measuring rates are achieved. The thickness values can be used to control the coating application and for quality assurance. Its laser-line beam design makes this sensor ideally suitable for inline thickness measurements in battery cell production. The electrode coating is a dried paste (the so-called slurry), which is applied on both sides of an aluminum film (for the cathode) or on a copper film (for the anode). Subsequent drying and calendering forms a partially very porous surface. Specially designed for measurements on rough surfaces, the small laser line is ideal for this application since it compensates for surface irregularities. The thickness values of the coated film obtained in this way are used for quality assurance. Thanks to its high accuracy and very compact size, the optoNCDT 1900 LL is ideal for these measurement tasks. Another advantage is the possibility of solving measurement tasks with laser class 2.
Capacitive distance sensors for roller gap control
State-of-the-art inductive sensors are normally used to monitor and control calender and coating rollers. As the requirements of end customers and plant manufacturers increase, Micro-Epsilon uses capacitive sensors, often in a flat design. These are available in various designs and detect the roller gap with micrometer accuracy. These 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, e.g. with a flat sensor only 0.9 mm thick. The sensor can measure on both sides and therefore detects two distances. Another option is indirect gap measurement via integration on the shaft using an extremely compact 4 x 3.5 mm capacitive sensor. Its robust design and high temperature stability allows the sensor to be used in high ambient temperatures.
Process-reliable distinction of black tones in battery production
The production of lithium-ion batteries requires maximum precision. In this ultra-modern manufacturing process, carrier films are combined with an anode and a cathode to form an energy cell. The anode consists of a copper film coated with a graphite layer in deep black. The cathode has an aluminum film with a deep black lithium metal oxide coating. The two shades of black can hardly be distinguished from each other. However, this is of great importance to ensure the proper functioning and reliability of the batteries. The colorSENSOR CFO200 color measuring system in conjunction with the innovative CFS2-M11 circular sensor reliably solves this measurement task and makes it possible to distinguish fine color nuances. The measurement takes place in real-time, with high precision and high speed.
2D/3D sensors and dimensional measurement technology for electrode and battery production
3D sensors from Micro-Epsilon are used for assembly monitoring and for 3D inspection of coated films. 3D laser scanners are used for continuous belt inspection, while 3D snapshot sensors are used for stop-&-go measurements with extremely high precision. The 3D sensors from Micro-Epsilon allow stable measurement with high resolution and detect flaws on the smallest of shapes, such as spalling and inclusions. Optical micrometers that reliably check sheet travel are used to monitor the edges of strips.
3D monitoring of the coating application on the belt edges
Electrodes must be coated with extreme precision. Therefore, laser scanners from Micro-Epsilon inspect the coating profile on the edge. This is how anomalies of the coating and undulations are detected. These 3D laser scanners are characterized by high dynamics, absolute precision and their compact size. With the scanCONTROL 3000 and the new scanCONTROL 3002 series, Micro-Epsilon offers a comprehensive portfolio with numerous measurement areas. The sensors are based on the latest GigE Vision and GenICam standards and can therefore be integrated in a wide range of image processing environments. The powerful 3DInspect software is available for parameter setting, evaluation and output.
Web edge control of electrode film
During the production of battery cells, electrode and separator films must be guided reliably. Optical optoCONTROL micrometers detect the required edge position for web edge control. Operating several micrometers enables the concurrent detection of the web width. Due to their high measuring rate, optoCONTROL micrometers are also suitable for monitoring dynamic production processes.
Inline systems for measuring the strip thickness of separator films and transparent plastics
The thicknessGAUGE sensor system is used for inline thickness measurement of strip materials. Equipped with a white light interferometer, it detects thin coatings from 10 µm on plastic films with sub-micrometer accuracy. Several models with different sensor types, measuring ranges and measuring widths are available from Micro-Epsilon for precise thickness measurement. Depending on the requirements of the measurement task, these systems use two optical or electromagnetic distance sensors to measure the strip thickness of cell material, films and coatings with micrometer accuracy.
Measuring system for high precision inline thickness measurement of battery film
The thicknessCONTROL measuring system is used for high-precision inline thickness measurement of coated battery film and impresses with long-term stable measurements. It consists of one or two robust measuring frames, each of which can be equipped with up to four thickness measuring tracks according to customer requirements. This allows up to eight thickness measurement channels in one measuring system. The sensors are based on the confocal chromatic measuring method and are evaluated and synchronized via a multi-channel controller. A patented linearization of the individual measuring tracks achieves measuring accuracies in submicrometers.
Conclusion:
The use of Micro-Epsilon sensors and sensor systems in battery production increases efficiency and quality and conserves resources. Micro-Epsilon develops, produces and distributes a globally unique range of sensors, measuring systems and customer-specific solutions. The company offers both sensor and system expertise with in-depth application know-how from a single source. The wide range of products is based on different measuring principles and is tailored to the high requirements of battery production. It is ideal for monitoring production processes in battery cell manufacturing. Various measuring methods are available for measuring the thickness of the battery film, which are optimized for the respective process steps.
Author:
Michael Kuran
Key Account Manager / Battery Industry Expert
MICRO-EPSILON MESSTECHNIK GmbH & Co. KG
Koenigbacher Str. 15, 94496 Ortenburg/Germany
Phone: +49 8542 168 0, Fax: +49 8542 168 90
www.micro-epsilon.com
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