Manufacturing of lithium-ion cells is a complex process with hundreds of steps. Factories need to be free of impurities, and in some steps, the humidity needs to be well controlled. The manufacturing process starts with slurry making, where the active material powder, conductive additive and binder are mixed together with a solvent. The resulting slurry is then coated on a current collector foil. After drying, the coating is pressed to a specified thickness. In the next step, the electrodes are cut to the right size and shape for the cell assembly.
The cell assembly line consists of several steps: The electrodes and separator are wound or stacked to form the designed structure. Current collector tabs and protective tapes will be added to the electrodes or to the cell structure depending on the design and used machinery, and finally the cell structure is put into a container.
In the last step, electrolyte is added to the container and the container is sealed hermetically. When the assembly is completed, the cell is moved to formation process, where the first charging is done. After the formation step the cell is finalized for the Pack production.