Measurement technology for the batteries of tomorrow

In battery production, high precision is essential to meet the high quality and performance requirements. Battery manufacturers are using inline thickness measurement systems, machine monitoring and 3D surface inspection systems to optimise processes and maximise quality, says Glenn Wedgbrow, Business Development Manager at Micro-Epsilon UK.

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 optimise the individual production processes and maximise quality.

various images of sensors in battery process — 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.

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 companies around the world and impress with their high precision and reliability in both series and OEM applications. The sensor signals can be calculated, evaluated and analysed using turnkey solutions.

More precision in battery production

Sensors and systems from Micro-Epsilon are used in highly automated processes in all production stages including anodes and cathodes, separators and active material. They measure with high precision during coating, calendering, assembly and 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 aluminium film. Process-critical parameters are the coating thickness, the 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

Production line with thicknessCONTROL system in position — The thicknessCONTROL Quad measuring system consists of two robust measuring frames, each containing eight confocal sensors.

The thicknessCONTROL measuring system from Micro-Epsilon 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 and results in much greater coverage and detection of thickness variations across the web width. The sensors are based on the confocal chromatic measuring method and are evaluated and synchronised via a multi-channel controller. A patented linearisation of the individual measuring tracks achieves sub-micrometre measurement accuracies.

Capacitive sensors have also proven themselves in the inline thickness measurement of battery film. These have a larger measuring spot, which means inhomogeneous structures 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. Due to integrated temperature compensation, they deliver stable measurement values in the sub-micrometre range.

Measuring the thickness of wet layers

Confocal chromatic sensors from Micro-Epsilon are also capable of monitoring the coating thickness of wet materials. These sensors provide both extremely high resolution and high measuring rates. Installing several sensors next to each other enables concurrent determination of the homogeneity of the coating over the complete strip width.

One-sided thickness measurements of battery electrode coatings

The new combiSENSOR KSB6430 combines an eddy current sensor with a capacitive displacement sensor in a single housing. This unique sensor concept enables high precision one-sided thickness measurements of battery coatings transported over chrome coated steel roller. Due to its robust design and high accuracy, the sensor is suitable for inline thickness measurements in battery film coating processes.

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 with high accuracy. Operating several micrometers enables the concurrent detection of the web width.

Offline thickness measurement of battery films

The new capaNCDT TFG6220 has been developed to determine the film thickness of test coupons from battery film production runs. The dual capacitive sensor system combined with an integrated vacuum bed ensures wrinkle-free support of the delicate material and enables offline thickness measurement with maximum precision for quality inspection and referencing of films.

Capacitive distance sensors for roller gap control

two calendar rollers with capacitive sensor measuring gap — Capacitive flat sensors are used for monitoring and controlling calender and coating rolls. These are available in various designs and detect the roller gap with micrometer accuracy.

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 its capacitive sensors, often in a flat design, to measure the direct roller gap. 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, for example, using a flat 0.9 mm thick sensor. 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 capacitive sensor with dimensions of just 4 x 3.5 mm. Its robust design and high temperature stability enables the sensor to be used in high ambient temperatures.

Measurement of axial roll runout

In order to enable the guide or coating rolls to operate at the highest precision, the axial roll runout is continuously measured. For this purpose, eddy current displacement sensors detect the axial movement of the roll by determining the distance to the roll. In addition to the compact design, the advantage of the eddy current sensors is their resistance to harsh environments: the sensors provide precise measurement results even when oil, dirt, temperatures or pressure act on the sensor. The compact eddyNCDT 3001 sensors also have an integrated controller, which further simplifies integration.

3D surface inspection

Two laser line sensors measure on battery foil — Electrodes must be coated with extreme precision. Laser scanners from Micro-Epsilon inspect the coating profile on the edge.

The scanCONTROL laser line profile sensors enable stable measurement with high resolution and can be used to build 3D visualisation and inspection of coated films and battery pouches. Defects with the smallest geometries, for example, spalling and inclusions, are reliably recognised and output by the sensors.

Coating application on edges

Electrodes must be coated with extreme precision. Any excess coating can build up along the coated edge which can cause issues when the material is being coiled. Therefore, laser scanners from Micro-Epsilon inspect the coating profile on the edge. This is how anomalies of the coating and undulations are detected.

Detection of curved edges after cutting

Films may have curvatures and deformations after longitudinal cutting. In order to detect these deviations reliably, laser profile sensors from Micro-Epsilon are used. Due to their extremely high resolution and insensitivity to reflecting surfaces, these sensors provide stable measurement results.

Position control of battery cells

After the battery cells have been assembled, laser scanners from Micro-Epsilon inspect their completeness and position. These precise profile sensors generate a 3D image that is then compared with the CAD data.

Battery expansion during charging

When the battery is first charged, the battery cell expands. To detect the critical point before rupture and to interrupt the charging process, the battery is installed in a test stand. Laser sensors from Micro-Epsilon check the vertical expansion in several charge and discharge cycles. The compact sensors can also be accommodated in confined spaces and deliver high measurement accuracy.

For more information, please visit www.micro-epsilon.co.uk or call the Micro-Epsilon sales department on +44 (0)151 355 6070 or email info@~@micro-epsilon.co.uk

Further Information

Battery Production

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