11 ways machine vision is used in electric vehicle battery production

Here at IVS our vision system solutions are utilised for the inspection of electric vehicle battery production. We thought it would be interesting in this post to drill down a little more of how machine vision is used in this fast-developing industry sector.

How are electric vehicle batteries made?

Carbon or graphite, a metal oxide, and lithium salt are all used to make lithium-ion batteries for electric vehicles. Positive and negative electrodes are made up of these elements, which when mixed with electrolyte form an electric current that allows the battery to work to power a car. It’s also the same type of battery that’s used in common devices like cell phones and computers, but on a far larger scale.

The materials used to make EV batteries come from many different countries and sources. Subterranean ponds are the most common source of lithium. The ponds liquid is drained out and left to dry in the sun. The Andes Mountains, which span through Chile, Argentina, and Bolivia, provides a large portion of the lithium used in electric car batteries. There are additional rock-mined deposits in China and the United States. The cobalt used in electric vehicle battery production mostly comes from mines in the Democratic Republic of Congo. Nickel is largely gathered in Indonesia and the Philippines. Lithium is converted to lithium carbonate, which is subsequently processed at a battery plant. The batteries are assembled at the production factory and then installed in an electric vehicle with zero emissions.

EV’s employ a pack, which is made up of thousands of separate Li-ion cells that work together, rather than a single battery like a phone. Electricity is utilised to make chemical changes inside the car’s batteries while it is charging. These adjustments are reversed when it’s on the road to generate electricity.

So how is machine vision used in a battery plant?

Machine vision is used in the complete electric vehicle (ev) manufacturing cycle, providing quality and consistency to the production across all areas. But getting the quality right on battery production for electric vehicles is critical for safety, life cycle and achieving greater energy density – and to prevent degradation and to minimise waste. Therefore, machine vision provides the eyes on quality in electrical vehicle manufacturing, providing 100% inspection, around the clock. From work we have done we can drill down on the 11 critical areas that machine vision is used in electric vehicle battery production for in-line quality control.

1. Coating quality inspection. During the initial coating process, linescan vision inspection is used to check for defects such as scratches, dents, dints, craters, bubbles, inclusions and holes on electrode sheets.

2. End face profile measurements. The end profiles can be continually monitored to quality assess the black electrode coating process and raise alarms in case of faults identified.

3. Coating width measurement. The anode and cathode coating has to be extremely consistent and to measurement specification. Therefore, surface inspection combined with gauging width and edge profiles helps to build up an inspection profile for the continuous coated product.

4. Electrode tab position and surface verification. During vacuum drying, a separator and electrode are brought together in cell construction. Cathode and anode cells are wrapped, rolled, or stacked together. The folded cells have lead tabs attached to them. When the cells have been loaded with electrolytes, vacuum-sealed, and dried, the procedure is complete. This process is monitored by vision inspection for anomalies and out of tolerance product. Critical to quality (CTQ) parameters are assessed in real-time.

5. Battery module defect detection. Each battery module will generally contain a number of cells (typically twelves). The modules are joined together and a cooling fluid pipe is attached. Checks for verification for module integrity, assembly characteristics and component verification are all completed using machine vision.

6. Stacking alignment and height. As modules and battery slices are built up into a complete battery pack, vision sensors measure the profile of the slice displacement and positioning to provide accurate feedback control for precision stacking.

7. Tab inspection. The tabs on the edge of each slice and subsequent modules are checked for debris, chips and cracks. Any small burr, edge deviation or dent can cause issues for the final assembled battery unit.

8. Connector Inspection. The main entry and exit to the battery module is via a high-voltage connector. The battery is charged through this connection, and electricity is delivered to the electric motor. Inspection of the main characteristics of the connector assembly are critical to provide a final check for edge deviations, male/female connector profiles and no cracks or dents in the connector profile.

9. Pouch surface inspection. Automated cosmetic inspection for inclusions, surface debris, scratches, dents and dints ensures that the lithium-ion cells are checked prior to becoming an EV battery.

10. Code reading. Codes on the battery modules need to be read for traceability and to track each element through the production process, allowing the manufacturing to trace where an EV cell is finally installed, from the individual production plant, down to the individual vehicle.

11. Final assembly verification. The final battery pack is checked for completeness to specification, all necessary assembly parts are available and verification of optical character recognition of codes for full traceability of the pack when sent to the customer for installation into the electric vehicle (EV).

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