product-guide
Do We Have to Serialize Every Single Cell for the Battery Passport?
The passport requires per-unit identity for the battery you place on the market — not (yet) for every cell inside it. Here's where the serialization line actually sits, and why it's moving.
The short answer
You need per-unit identity for the battery you place on the market — every pack gets its own serial and its own passport record. You do not (today) need a passport per cell. But cell-level marking is the direction of travel, and understanding why helps you decide how far to invest now.
Why batteries are item-level when textiles aren't
Passport granularity comes in three levels — model, batch, item — and each category's rules pick one. A first-wave textile passport is expected at model level: one record per SKU. Batteries sit at the other extreme: item-level from day one, because tracking a battery through repair, reuse, and recycling requires knowing this specific unit's history, not its SKU's. A T-shirt doesn't have a state of health; your pack does.
In identifier terms: a product code alone gives model level, adding a batch code gives batch level, adding a serial gives item level. Battery passports live at the third.
The disassembly problem — why the line is moving below the pack
For most of the past decade, traceability in battery manufacturing stopped at the pack: one identifier on the housing satisfied recall requirements, and cells were tracked by batch only. The passport era breaks that model at a specific, physical point: when a pack is opened for second-life use or recycling, the pack-level identifier dies with the housing — and the passport data has nothing to follow. The unit whose provenance matters at that moment is the cell.
That's why cell marking is moving to laser and dot-peen at cell level among serious manufacturers, and why MES-driven genealogy (which batch of slurry went into which numbered cell) is becoming the backbone of passport data at the high end.
What's required vs. what's frontier
Be careful not to over-scope. Full continuous traceability at single-cell level — linking electrode production to a specific finished cell — is not reliably solved anywhere today; it's an active research frontier, not a 2027 requirement. What 2027 requires of you:
- A unique identifier per battery placed on the market.
- A passport record resolving from that identifier.
- Build genealogy good enough to state what went into that unit — cell lots, chemistry, origins.
Cell-lot-level genealogy tied to a pack serial meets the moment. Per-cell serialization is a competitive investment, not a compliance gap.
What this means for your team
Check two things on your line this month: that every finished unit gets a durable unique identifier, and that your build records can answer "which cell lots are in serial #X?" If both hold, your serialization story for 2027 is sound — and cell-level marking can be evaluated on its second-life business merits rather than out of deadline panic.