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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Outgoing

Subject	Property	Object
Cell manufacturing/Formation	HasPredecessor	Cell manufacturing/Electrolyte Filling
Cell manufacturing/Formation	HasSuccessor	Cell manufacturing/Degassing