Production of lithium-ion batteries

Today’s automotive market is dynamically changing. Car manufacturers are firmly focused on developing electromobility, and the sight of an “electric” on the road no longer surprises anyone. Without a doubt, one of the most important parts of an electric car is its battery – it is the one that stores the energy with which the vehicle can be put into motion. However, before the battery is in your car, it must first go through a rather complicated and demanding manufacturing process.

Types of batteries that electric vehicles have

However, first a few words of theory. Currently, the most popular choice in electric vehicles are lithium-ion batteries, due to the fact that they allow you to cover more miles on a single charge compared to other types of batteries. These types of batteries are made up of any number of cells connected in series to form so-called modules. The individual members, or cells, of the battery store energy and consist of a separator and two electrodes (positive and negative) separated from each other by electrolyte. They can take a cylindrical shape or a flatter form….

Longevity of lithium-ion batteries – manufacturing batteries for electric cars is an extremely difficult affair

In order for a battery to serve us for as long as possible, the process by which it is manufactured and put together is very important. We need to be sure that the dimensions of each part and entire components are within the specified tolerances, and that the final product is made in such a way that it is completely safe and achieves maximum duty cycle time.

Vision systems, which are increasingly being used during the various stages of electric vehicle battery production, can assist us in this.

Production of lithium-ion batteries – steps in the production of batteries for electric vehicles. How are batteries manufactured?

Single cell design and control

A major challenge in constructing a cell is to properly assemble all the materials together so that the electrolyte is evenly coated on the surfaces of the copper and aluminum foils to facilitate current flow. Moreover, the foils should not touch each other, so the metal surface, separator and coating must be checked for any surface or edge defects, as well as uniform shape and thickness.

Using a vision system for this purpose, or more precisely, a 3D scanner, ensures accurate measurement of the width of the separator and electrode dimensions. It also makes it possible to quickly determine the edge profile of coated electrode sheets. The scanner can also measure the distances between tabs on the cell sheet to ensure that the required dimensional tolerances are always maintained.

• Cell assembly

During cell assembly, the separator and electrode are joined together, and the combined cell (along with the anode and cathode) is rolled, rolled or stacked. The stacked cells are then placed in a metal housing and sealed by welding.

In this case, the vision system can be used to scan sheets of cells and check that they are stacked correctly. With built-in tools to detect the position of the parts in question, the scanner is also able to check the correct position of the completed weld. Before the welding process takes place, however, the device can also check the surface and then measure the gap between the battery cell and its metal housing. It is also an excellent tool for checking the quality of the welds made. It checks them for the correct height and various types of cracks and lint.

• Quality control of the cell surface

After assembly, the battery cells are thoroughly inspected for surface quality, degree of flatness and its potential damage, such as cracks or edge defects. In the case of cylindrical batteries, he also inspects their quality for dents, scratches and dirt. It is also important to check the sealing of the lithium-ion battery, damage to which can be effectively detected by the vision scanner.

• Combining cells into modules

At this stage, the cells are combined into modules containing several to a dozen cells connected in series. The modules are welded together to form battery packs. Both at the stage of creating modules and whole sets, all components must be checked for correct assembly and the quality of the final welds.

A vision system in the form of a laser scanner works well in cell manufacturing because it can handle highly reflective surfaces, such as welds are. It quickly identifies their defects, such as cracks, lint, offsets or air holes. It also “spots” excessive changes in weld surface roughness and discoloration.

• Final battery installation

Batteries are mounted in cars in such a way that they are least likely to be damaged. In electric vehicles, there is usually a plate under the floorboard to which the lithium-ion battery module is glued. The application of the adhesive layer in this area must also be strictly controlled, both for correct dimensions and for the quality of the bonding surface.

At this stage, inspection using vision systems makes it possible to take measurements of width, height, offset and continuity checks at specific points along the glue path.

Summary

Trends in the electric car battery market are constantly changing. And although electric car manufacturers are outdoing themselves with concepts for new batteries, one thing is certain. Regardless of their characteristics, such as capacity, type of cell or electrolyte, what matters most is getting a well-made and fully operational product. Optimized quality control using vision systems makes it possible to quickly detect defective raw material, thereby reducing costs and increasing the safety and durability of the battery. Vision systems are indispensable in the production of batteries for electric cars. It is not without reason that Europe’s largest car battery production center is reaching for them.