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Cell-Finishing

A factory concept for formation of large quantities of
Li-Ion cells for electric vehicles.

For the Chinese page click here.

Formationsanlage
1. Entry of the cells out of the cell manufacturing

At this stage the cells are handed over from the cell manufacturing to the formation and finishing. The cells are placed into special heat resistant, non-flammable and chemically resistant product carriers.

2. Clamping of the cells for the formation

The battery cells are placed into special clamping pallets in order to keep the face sides compressed. That facilitates an even ion transition within the cell.

3. High temperature aging

At this Stage the cells will be heated up to lower the viscosity of the electrolyte to facilitate an even wetting process. Chemical processes as e.g. the forming of the SEI layer accelerate also at higher temperatures.

4. Cooling channel for the heated cells

Before the final processing the cells need to be cooled down. That happens in a cooling channel where fans from each side blow cool air onto the cells during their transport.

5. Formation

This stage is the main and most important process in the value chain of the Li-Ion cell formation. Here, the cell is slowly being charged and hence raised to life.

Due to the fact that faulty cells could heat up to critical temperatures and eventually start burning or even explode the formation chambers need to be built fire-proof.

The formation process takes normally several hours.

6. Maintenance area

This station is necessary for the manual maintenance and failure removal of the formation chambers, e.g.:

- Replacement of wear parts (contacting pins)

- Control and calibration of sensoric and mechanic

- Overhaul after incident or thermal runaway

The maintenance takes place outside of the formation area in order not to interrupt the normal process.

7. Degassing and final closing

As a side effect during the formation process certain gases are generated. Those need to be sucked out of the cell. That is done by exposing the cell to a vacuum. After that the cell is being finally sealed.

8. Aging of the cells

In an high rack storage area the charged cells are aged for several days. During this time a passivating layer the so called Solid Electrolyte Interface is being finally formed.

9. Separation of cells

Certain processes require the individualization of the cells as a bulk processing in the carrier is not possible.

10. Isolation of the cells

After the quality check, an isolation foil can be added to the cells in order to secure and label them.

11. End-of-Line-Test

After the cell is finally processed it will be taken to a final check. There the mechanical properties as tightness, weight and outer dimensions can be checked as well as electrical characteristics such as isolation, inner resistance and open circuit voltage.

12. Sorting / grading of the cells

Each individual cell provides little quality differences due to the very complex manufacturing process. For the further processing the cells are sorted into different grades

13. Final good storage

In order to create a buffer before shipment the cells or boxes can be stored in another high rack storage.

14. Packaging

According to the customer and transport requirement the cells can be packed from very simple up to seawater-resistant in different quantities and box sizes.

Formation

At the production of Lithium-Ion battery cells the final steps are the forming of the passivating layer (SEI), the aging process, the classification and the final quality test.

For that reason it is necessary to slowly charge and discharge every cell as well as to age and test them.

For the production of battery for electric cars a high number of cells are necessary. Therefore large plants for formation and test are necessary.

The following processes may be a part of the formation:

  • Clamping of cells for formation
  • High temperature aging
  • Cooling buffer
  • Cell formation
  • Degassing and final closing
  • Aging of cells
  • Isolation of cells
  • End-of-line test
  • Charging to SOC
  • Sorting/grading of cells
  • Warehouse
  • Packaging

General data

  • Dimensions of the hole plant L, W, H: 180m x 120m x 15m
  • Fully automated plant
  • Highly efficient electronics with high availability
  • Monitoring of all processes
  • Fire protection

For more information please click here

  • Electric Mobility

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