Metal particle contamination

Example

Use in Lemonergy

Place operations and quality checks in process order.

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Burr

A sharp raised lip of foil, or a loose flake of coating, left at a cut electrode edge by slitting or notching. The separator is only about 10–25 µm thick, so a burr of similar height can pierce it under stack pressure and cause an internal short circuit; edges are therefore inspected and worn knives replaced before burrs grow.

Cleanroom

A room whose airborne particle count is held to a class by filtered air, overpressure and gowning, graded under ISO 14644-1: ISO class 7 allows at most 352,000 particles of 0.5 µm or larger per cubic metre. It controls particles, whereas a dry room controls moisture; cell assembly usually needs both, because one metal particle can short a cell.

Internal short circuit

An unintended electronic path between the electrodes inside a cell — through a metal particle, a burr, a damaged separator or lithium deposits. It discharges the cell internally and turns its energy into local heat.

K-value

The rate at which a cell’s open-circuit voltage falls during the production aging step, in millivolts per day. A high K-value signals an internal short or contamination, and such cells are scrapped before shipment.

Self-discharge

The slow loss of stored charge while a cell is not in use. An unexpected rise can signal a leakage path or a soft internal short.

References & further reading

Further reading on this topic

These sources provide broader context; they are not presented as citations for every statement in this entry.

1. Current and future lithium-ion battery manufacturing

   Yangtao Liu, Ruihan Zhang, Jun Wang, Yan Wang · iScience · 2021

   Topic background · Electrode preparation, cell assembly, formation and manufacturing trade-offs.