Lithium-Ion-Battery

The battery industry is developing faster and more dynamically than ever before. With the increasing importance of electromobility and stationary data storage, pressure is growing on the industry to rapidly advance the development of lithium-ion batteries. Longer distances and higher performance are just as much a benchmark as increasing battery life and reducing production costs.
The solution to meet the benchmark requirements is extended industrial production. Industrial production enables parallel cost degression and quality improvement in terms of economies of scale, automation and technical innovation as well as resource and energy efficiency.

Electrode production and cell assembly in the Li-Ion battery industry

When processing the material webs to produce lithium-ion batteries, absolute precision is necessary for a safe and high-quality product. Only a qualitatively perfect lithium-ion battery can meet the high demands of the end product, especially for e-mobility.

One challenge is the exact guidance and positioning of the material webs in the individual processing steps, as different webs must be correctly controlled and measured in relation to each other. BST solves this task by utilizing its broad product portfolio, which includes inspection and web guiding systems.

On the one hand, inspection systems can perform various measuring tasks, but on the other hand, their measurement data can also be passed on to the web guiding systems and thus optimize their control results. The networking of the BST systems via the PROSolutions  visualization and operating platform offers customers a comprehensive solution which ranges from the provision of production quality relevant data to combined web guiding systems with intelligent sensor technology.

Process steps of battery production

Our products and solutions are represented in the following process steps:

Coating

The carrier foil (copper or aluminium) is usually coated via a slotted nozzle (slurry). Coating is done either continuously or intermittently on 1 to 3 webs.

The top and bottom sides of the film are coated either sequentially (2 process steps in the same line), one after the other on both sides (1 process step in one line) or simultaneously in the air flotation dryer process (1 process step in one line). After the drying process, the material is rolled up again.

Our solutions for quality assurance in coating include web guiding, top to bottom layer position control and surface and edge inspection for all relevant coating options.

Calendering

When calendaring, the copper or aluminium foil coated on both sides is compacted by a rotating pair of rolls. For this purpose, the material rolled up in the coating line is unrolled on the calendar and rolled up again after calendaring.

This is where customers want to make full use of the machine speeds! However, they are then faced with the challenge of ensuring that everything runs in a controlled manner - from unwinding the material to guiding it through the production process and winding it up.

BST eltromat offers a comprehensive web guiding system with different actuators, control devices and sensors, which covers the most diverse requirements. Thus, processes can be stabilized, waste can be minimized, and downtimes can be reduced.

Slitting

The large calendared parent roll is now processed to the slitting line. Here, a slitting process (video: Battery Slitting) cuts the material web in longitudinal direction with rotating knives into several smaller webs (longitudinal cut). The individual daughter rolls are separately rewound after the slitting process.

In order to fully utilize the machine speeds and at the same time ensure that all daughter rolls are wound up perfectly, BST web guiding systems are used. In addition, the slit width of the individual webs can be monitored with a width measurement based on the web itself or the slurry and can also be controlled via the PROSolutions  visualization and operating platform.

Separating

The separation of the individual components is necessary to produce battery cells. Here, the anodes or cathodes are cut out of the daughter rolls in a continuous process using punching or laser cutting. This leaves the so-called tabs, which later serve as the electrical connection for the batteries.

BST eltromat offers solutions to position the material web exactly to the laser cutter. These solutions ensure that the tabs meet the geometrical requirements of the base material for coating.

Furthermore, the inspection solution "Shape Measurement" enables the monitoring of the geometric conditions, which can also be fed back into the process via the visualization and operating platform PROSolutions. For rewinding the material, the BST web guiding standard function "Tab Ignoring" (Video: Tab Ignoring) is absolutely necessary.

Half-Slitting

This is the subsequent process of separation to produce a battery cell. In a slitter, the daughter rolls with the tabs are halved and rolled up again.

To ensure precise web guiding, the BST web guiding system is used. The standard function "Tab Ignoring" (Video: Tab Ignoring) is mandatory to ignore the tabs during web edge control. This is the only way to precisely position the material in front of the rotating knife and cut the material exactly in half (from the material edge or slurry edge).

In addition, the cut width of the individual webs can be monitored with a width measurement (of the web or slurry) and also controlled via the PROSolutions visualization and operating platform.

Stacking / Winding / Laminating


Winding (Prismatic / round cell)

Winding in the production process of prismatic cells and round cells takes place after the "half-slitting" of the daughter rolls. Here, the electrode tracks and two separator tracks are wound around a winding mandrel (prismatic cell) or a central pin (round cell).  Like the laminating and stacking process (link to paragraph below), the challenge in this process is to bring the webs together with high precision.

BST eltromat solves this task by networking several web guiding systems (Video: connectivity of web guiding), which additionally access functions such as master/slave and offset correction. In this way, the individual edges can be easily controlled back in case of deviations from their intended position and the exact guiding of different webs to each other and through the process step up to winding can be ensured.

Laminating and Stacking (pouch cell)

In this process step the monocell is produced from the supplied materials (4 layers = 1 anode + 1 cathode + 2 separators) by a high precision combining and laminating process. In the subsequent process, the merged material web is then cut and stacked accordingly.

In this process it is particularly important to bring the webs together with high precision. Based on decades of experience in the field of web guiding, BST combines several web guiding systems in this process step and adds additional functions such as master/slave and offset correction. Deviations from the nominal positions of the individual edges can thus be compensated and the exact guidance of different webs to each other can be ensured. To ensure reliable edge detection, BST has developed a special sensor especially for this process, which provides all relevant contrast, object and layer information to the PROSolutions visualization and operating platform.