21700 lithium cell — Ø21 × 70 mm cylindrical cell
The 21700 (Ø21 × 70 mm) is the higher-energy successor to the 18650: a larger can that delivers more capacity and lower internal resistance per cell, which means fewer cells, fewer welds and lower pack cost for the same energy. We offer it in NCM, LMFP and LiFePO4 chemistry across 27 variants, with rated capacities from roughly 2400 mAh to 6000 mAh.
How to read the model number
The prefix marks the chemistry (INR = NCM, IFR = LiFePO4) and the suffix marks the type:
- D — high-power: high continuous and pulse discharge for tools and traction.
- E — energy-storage: maximum capacity per cell for runtime-driven packs.
- P — high C-rate: highest discharge rate for demanding loads.
- PL — low-temperature: stable discharge in cold climates.
- M / MF — high-safety (LMFP / LiFePO4): longer cycle life and thermal stability.
For example, an INR21700-50E is a 5000 mAh NCM energy cell. Full per-model
specs — weight, internal resistance, charge/discharge rates, cutoff voltage and
cycle life — are listed in the table above and in the datasheet.
Spotlight: INR21700-50 — 5000 mAh in two builds
Our most-requested 21700 is the 5000 mAh INR21700-50, available as the high-power 50D and the energy-optimized 50E. Both share 5000 mAh nominal (4900 mAh minimum) capacity, 3.6 V nominal voltage, ≤18 mΩ AC internal resistance, ≤72 g weight and a 15 A (3C) continuous discharge rating with 5C pulse. Where the factory test data separates them:
| Factory test spec | 50D (high-power) | 50E (energy) |
|---|---|---|
| Max continuous charge | 1C (5 A) | 0.5C (2.5 A) |
| Cycle life to 80% | ≥600 cycles (1C/1C) | ≥800 cycles (0.5C/1C) |
| Capacity retention at 3C discharge | ≥92% | ≥93% |
| Relative capacity at 55 °C | ≥95% | ≥98% |
| Relative capacity at −20 °C | ≥60% | ≥70% |
| Max size with PET sleeve | Ø21.7 × 70.9 mm | Ø21.0 × 70.0 mm |
Rule of thumb: take the 50D when the application needs 1C fast charging — shared e-mobility, tools that recharge between shifts. Take the 50E when runtime, cycle count and temperature tolerance matter more than charge speed — home and commercial energy storage, UPS, telecom backup.
Both builds pass the full abuse-test program — external short circuit, overcharge, over-discharge, forced discharge, 13 kN crush, impact, 130 °C hot oven, 11.6 kPa altitude simulation, vibration and 1 m drop — with no fire and no explosion, and hold ≥90% capacity after 28 days fully charged at 25 °C. Full test tables: INR21700-50 specifications · 50D vs 50E compared · Request the full datasheet →
Typical applications
The 21700 suits e-bikes & e-scooters, cordless power tools, drones & UAVs and energy-storage systems. Choosing between formats? Compare it with the 18650.
Sourcing & OEM/ODM
- 27 variants across NCM, LMFP and LiFePO4 — high-power, energy and high-safety types.
- UN38.3 transport tested; manufacturer cell-safety certificates (UL / IEC / CB) available by model — see quality control.
- OEM / ODM: own-brand label, custom capacity binning and packaging.
- Datasheet, certificates and wholesale pricing provided after the RFQ.