21700 vs 4680: what the larger format changes
The 4680 is a bigger can with a different internal construction. Whether that matters to your pack depends on three things — cell count, thermal path and whether you can buy the cell.
In short
A 4680 cell is 46 mm in diameter and 80 mm tall, against 21 mm by 70 mm for a 21700 — roughly five times the volume. That buys fewer cells per pack and lower assembly cost, but it also means less surface area per unit of stored energy, harder thermal management, new tooling, and a supply base that is far narrower than the 21700 ecosystem.
At a glance
21700 and 4680, side by side
Every figure in this table is traceable to a model page or a manufacturer document. Where a value is not published in the source we hold, the cell says so rather than carrying a plausible-looking number.
| Attribute | 21700 | 4680 | Note |
|---|---|---|---|
| Nominal diameter | 21.2 mm | 46 mm | Larger can, thicker wall |
| Nominal height | 70.0 mm | 80 mm | |
| Volume per cell | About 24.8 cm³ | About 133 cm³ | Roughly 5× the 21700 |
| Cells for a 48 V, 20 Ah pack | 13S4P = 52 cells | 13S1P = 13 cells at ~20 Ah/cell | Would depend on final capacity per cell |
| Assembly joints per pack | 104 welds at 2 per cell | 26 welds at 2 per cell | Fewer joints, less assembly time |
| Surface area per Wh | Higher | Lower | Heat is harder to remove at the same energy |
| Ecosystem maturity | Broad — holders, strip, BMS, second sources | Narrow outside the originating manufacturers | |
| Second-sourcing | Four manufacturers in this catalogue alone | Very limited | The deciding constraint for most buyers |
| Stocked here | Yes — 12 models | No — not stocked | Stated plainly rather than implied |
The geometry decides more than the data sheet
Cell format is a mechanical decision with electrical consequences. A larger can holds more active material, so fewer cells are needed for the same pack energy — which reduces welds, balance taps, busbar length and assembly labour. That is the real argument for 4680, and it is an argument about manufacturing cost, not about electrochemistry.
The counter-argument is thermal. Heat leaves a cylindrical cell through its surface, and surface area grows with the square of the radius while volume grows with the cube. A 4680 has roughly five times the volume of a 21700 but only about twice the surface area, so each unit of stored energy has less area to dissipate through. In a low-current storage application that is manageable; in a high-current one it becomes the design constraint.
Tabless construction, and why it is mentioned
The 4680 is closely associated with tabless electrode designs, where current is collected along the full electrode edge rather than through a small tab. That lowers internal resistance and improves heat distribution inside the can — both of which partly offset the surface-area problem. It is a genuine engineering advance, and it is also the reason the format is not simply "a bigger 21700": the internal construction changed with the size.
For a pack designer the practical consequence is that 4680 performance figures cannot be inferred by scaling 21700 figures. Resistance, thermal behaviour and rate capability are properties of the specific design, and the design is not standardised across manufacturers the way the 18650 and 21700 footprints effectively are.
The availability question, stated plainly
This catalogue does not stock 4680 cells, and we are not going to imply otherwise. The format is produced in volume by a small number of manufacturers, much of it captive to specific vehicle programmes, and the merchant market for single cells is thin compared with the 21700 market.
That matters beyond price. A pack built on a cell with one or two sources has no second-source option when a batch is delayed, and no fallback when a design revision changes the part. For most industrial and storage builds the 21700 remains the format where you can qualify two electrically comparable parts from different manufacturers — which is worth more over a product lifetime than a lower cell count.
When the larger format would be the right answer
- The pack is large enough that cell count dominates assembly cost — hundreds of cells, not dozens.
- The duty is moderate in current, so the reduced surface area is not the binding constraint.
- The product volume justifies new tooling and a single-source qualification.
- You have a supply agreement that makes the cell available for the product lifetime, not just for the prototype.
If those four hold, the format is worth evaluating. If any of them fails — particularly the last — the arithmetic that looked attractive on cell count stops being the deciding factor.
What we can quote today
21700 cells from four manufacturers, 4,000 to 5,650 mAh, 7 A to 60 A continuous, with manufacturer data sheets held for the Molicel models and specifications marked pending where no data sheet is on file.
Questions about this comparison
Is a 4680 cell more energy dense than a 21700?
Per cell, substantially. Per unit volume the gain is smaller than the volume ratio suggests, because can walls, caps and current collection take up space in both formats. Per unit mass, the difference depends on the specific design rather than on the format.
Can I use 4680 cells in a pack designed for 21700?
Not without redesigning the mechanical structure, the interconnect, the BMS current sensing and almost certainly the thermal path. The electrical configuration would also change because the cell count changes.
Why is 4680 hard to second-source?
Because the format is not standardised across manufacturers the way 18650 and 21700 are. Dimensions may match while internal construction, weldability and thermal behaviour differ, so a substitute is a new qualification rather than a drop-in.
Does this site sell 4680 cells?
No. The catalogue covers 18650, 21700, 18500, 22700 and prismatic formats. This page exists so that a search for 4680 lands on an accurate explanation rather than on an implied product.
Related
Where to go next
Settled on a cell? Send the duty profile.
Give us the continuous and peak current, the envelope and the target cycle life. We will confirm what is obtainable and which documents travel with it.