Cell manufacturing/Formation

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|label=Cell manufacturing/Formation
|description=
===Production process===

*Formation is first charging and discharging processes of the cell
*Cells are stored in formation racks and contacted by spring-loaded contact pins
*Cells are charged / discharged according to predefined current and voltage curves
*During formation, lithium ions are embedded in the crystal structure of the graphite on the anode side which leads to formation of the Solid Electrolyte Interface (SEI); SEI creates an interface layer between electrolyte and electrode
*Parameters during formation have high impact on cell performance

===Process parameters & requirements===

*First charge: approx. 0.1 C - 0.5 C; SOC approx. 20 % - 80 %
*Successive increase in C-rates with each charging and discharging cycle
*Duration: up to 24 h
*Low contact resistances at the spring-loaded contact pins

===Technology alternatives===

*Different formation procedures 

===Quality influences===

*Orientation of the cells
*Contact method
*Process temperature
*Pressurisation, especially of pouch cells

===Quality features===

*Formation of the SEI layer
*Stability of the SEI layer
*Internal resistance of the cell

===Source===
Heimes, H.H.; Kampker, A.; Lienemann, C.; Locke, M.; Offermanns, C.; Michaelis, S.; Rahimzei, E. (2018) ''Lithium-Ion Battery Cell Production Process''; PEM of RWTH Aachen and VDMA, 3rd Edition, ISBN:978-3-947920-03-7

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