and mixing
![](/en/report/2023/bmw-group-report/cell-intelligence/02-pipette-desktop.jpg)
Cell production begins by making the electrodes. First, the different active materials are combined with binders and solvents in set quantities, creating the slurry.
and drying
![](/en/report/2023/bmw-group-report/cell-intelligence/03-slurry-desktop.jpg)
The slurry is applied to very thin metal foils and the coating then dries over 25 metres.
![](/en/report/2023/bmw-group-report/cell-intelligence/04-walzen-desktop-01.jpg)
![](/en/report/2023/bmw-group-report/cell-intelligence/04-walzen-mobile-02.jpg)
Several pairs of rollers compact the coated foils in a process known as calendering. This a highly precise process, as the foil is only a few micrometres thick – thinner than the threads of a spider’s web. The coating is also only micrometres thick.
![](/en/report/2023/bmw-group-report/cell-intelligence/05-gehaeuse-mobile-01.jpg)
![](/en/report/2023/bmw-group-report/cell-intelligence/05-gehaeuse-desktop-02.jpg)
In the cell assembly stage, the coated foils – known as calendered electrodes – are wrapped around jelly rolls with a separator and inserted into the cell housing. The cells are then filled with electrolyte.
![](/en/report/2023/bmw-group-report/cell-intelligence/06-zelle-desktop.jpg)
The round cells are charged for the first time and then checked.