Cell Review: Sodium-ion Layered Oxide, 18650
Layered Oxide Sodium-Ion 18650 Cell: Cold-Ready Power Without Lithium
Why this matters: Sodium-ion cells are a real alternative to lithium-ion. But which sodium-ion should you choose? This cell uses a layered oxide cathode, runs at about 3.05 V nominal, and still discharges in deep cold where normal lithium cells struggle. It comes in the familiar 18650 format, so you can build packs with normal tooling and normal holders.
What's the Difference Between Sodium-Ion and Lithium-Ion?
This graph shows how layered oxide, NFPP, and LFP 18650 cells differ while charging at 0.5C. The LFP cell (green) jumps quickly, then sits on a long flat plateau around 3.3 to 3.4 V before climbing to its 3.65 V charge limit at the very end. That flat curve is why LFP state of charge is so hard to read from voltage. Both sodium-ion cells rise gradually with no true plateau. Layered oxide (blue) climbs to nearly 4.0 V, while NFPP (orange) tops out at 3.7 V. The sloping curve is a gift for DIY builders: voltage actually tells you where you are in the tank.
Batch note: This review covers the 1,300 mAh cell (manufacturer part number NaCR18650-1.3ER). Sodium-ion is moving fast and our stock rotates, so the cell shipping today may have a different capacity, voltage window, and current rating. The product page always shows the batch currently on the shelf, plus archived datasheets for every batch we've sold. If you bought the 1,300 mAh cells, the BMS settings below are yours.
How This Layered Oxide Cell Compares to NFPP, NFM, and LFP
You'll see a few different sodium and lithium chemistries in the store. Here's the plain-English version of where this cell sits:
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Layered oxide vs NFPP (sodium iron pyrophosphate, "phosphate-style sodium"):
NFPP behaves like "the LFP of sodium-ion." It's stable, forgiving, has excellent safety, and is very good in the cold. Its voltage curve shows distinct steps rather than one smooth slope. This cell is still sodium, but it's a layered oxide instead of a phosphate. Result: a higher top-of-charge voltage (3.95 V vs 3.7 V) and more energy per cell, while still working in sub-zero temps. NFPP usually wins on cycle life. Read the NFPP 18650 review. -
This cell vs NFM (sodium nickel-iron-manganese oxide):
Here's the part most sellers get wrong: NFM is also a layered oxide. "Layered oxide" is a family of cathodes, not one recipe. High-nickel versions like NFM chase energy density and can reach the top of the sodium range. Lower-cost versions trade some of that energy for rate capability, cold performance, and price. This cell lands at about 109 Wh/kg, toward the lower-energy, higher-rate end of the family. If you're counting grams, look at NFM. If you want multi-C bursts and cold-weather discharge, this cell is the better fit. More in NFPP vs NFM. -
Layered oxide vs LFP (LiFePO4):
LFP is still the king for cycle life (often 4,000 to 6,000+ cycles in large prismatic cells) and maturity. But LFP can't be charged below 0 °C without risking lithium plating, and it loses a big chunk of capacity well below freezing. This cell discharges down to −40 °C and accepts charge down to −20 °C at reduced current. If you're building storage for an unheated shed, cabin, or outdoor enclosure in winter, that matters a lot.
What Is a Layered Oxide Sodium-Ion Cell?
A layered oxide cathode stacks sodium ions between sheets of transition-metal oxide. The metals used (nickel, iron, manganese, copper, chromium) set the energy density, cycle life, and cost. The manufacturer's "NaCR" model prefix hints at a chromium-based recipe (NaCrO2), but the datasheet never states the cathode, so we don't claim it. What we can see is the smooth, sloping charge and discharge curve on our own bench, which is the signature of a layered oxide. This cell gives you:
- About 3.05 V nominal per cell and a wide working window (1.8 V to 3.95 V per cell).
- Cold-weather performance that stays usable at sub-zero temperatures, including discharge down to −40 °C.
- Sodium instead of lithium and cobalt: more abundant materials and less supply chain drama.
Practically, you can design a multi-cell pack (12 V, 24 V, 48 V) almost the same way you'd design around LFP. The series counts and BMS settings are different, and you get better low-temp behavior than typical LFP cells.
Electrical & Mechanical Specs (1,300 mAh Batch)
| Parameter | Value |
|---|---|
| Chemistry | Sodium-ion, layered oxide cathode |
| Manufacturer Part Number | NaCR18650-1.3ER |
| Nominal Voltage | 3.05 V |
| Voltage Window | 1.8 V (cutoff) to 3.95 V (charge limit) |
| Rated Capacity | 1,300 mAh @ 0.2C |
| Energy | ~3.97 Wh per cell (~109 Wh/kg) |
| Internal Resistance | ~30 mΩ |
| Standard Charge Current | 0.5C (≈650 mA), CV taper to ≤0.05C |
| Max Charge Current | 1.0C (≈1,300 mA) |
| Standard Discharge Current | 0.5C (≈650 mA) |
| Max Discharge | 7.8 A (~6C) at 25 °C, 100% SOC |
| Operating Temp (Charge) | −20 °C to 55 °C |
| Operating Temp (Discharge) | −40 °C to 60 °C |
| Cycle Life | ≥1,000 cycles to 80% |
| Dimensions | Ø18.35 ± 0.15 mm × 65.2 ± 0.2 mm |
| Weight | 36.5 ± 0.5 g |
| Storage Temp | 15 °C to 35 °C recommended |
Cell Testing Results
Quick Comparison
| Chemistry | Nominal V / Cell | Energy Density | Cycle Life Class | Cold Behavior | Typical Use Case |
|---|---|---|---|---|---|
| Layered oxide (this cell) | ~3.05 V | Moderate (~109 Wh/kg) | 1,000+ cycles | Excellent (down to −40 °C discharge) | Outdoor / cold-climate packs that still need burst current |
| NFPP (sodium iron pyrophosphate) | ~3.0 V | Lower to moderate | 2,000 to 4,000 cycle class | Excellent, very stable and safe | Long-life stationary storage, safety-first builds |
| NFM (high-energy layered oxide, Na-Ni-Fe-Mn) | ~3.1 V | Highest for sodium-ion | ~2,000 to 3,000 cycle class | Good, but not as forgiving as NFPP in deep cold | Energy-focused builds where Wh/kg matters |
| LFP (LiFePO4) | ~3.2 V | High for stationary cells | 4,000 to 6,000+ cycle class (large prismatics) | Fair: needs heat in winter, no charging below 0 °C | Home ESS / off-grid banks where you can control temp |
Where These Layered Oxide Cells Make Sense
- Cold-climate storage: Cabin, garage wall, outdoor box, van in winter. You don't always get to keep the pack warm.
- DIY 12 V / 24 V / 48 V packs: Standard series/parallel builds work fine. At ~3.05 V per cell, a 48 V pack is 16S, the same count as LFP.
- Prototyping sodium-ion: Because this is a normal 18650 can, you can spot-weld nickel strip and use off-the-shelf 18650 holders instead of designing compression plates like with big prismatics.
- Portable gear and test rigs: The ~6C rating means you can pull short high loads without the cell collapsing.
Build Notes & BMS Settings
- Charge limit: 3.95 V per cell max. Use CC/CV and stop when the taper current falls below ~0.05C. Do not use a lithium-ion or LFP charging profile without reconfiguring it.
- Low cutoff: 1.8 V per cell is the absolute floor for this batch, not a working setpoint. The sodium discharge curve slopes hard at the bottom, so there's very little energy left below about 2.5 V per cell, and most inverters will fault out first anyway. Set your BMS low cutoff around 2.5 V per cell.
- BMS: A stock lithium BMS won't work out of the box; the thresholds are wrong in both directions. Use a sodium-specific BMS or a programmable unit (Daly, JK, ANT) that lets you set custom cutoffs.
- Don't mix batches: Cells from different batches have different voltage windows and won't balance in one series string. Buy every cell for a pack, including spares, in one order.
- Packs: Treat these like any other cylindrical cell pack: fuse or protect parallel groups, then series-stack those groups. Run a balance lead to each series group.
- Spot welding: Start with the lowest weld energy and shortest pulse your welder offers. Increase slowly only if the nickel tab doesn't stick. Sodium-ion cells can be damaged internally by too much heat, and you won't see it until the pack underperforms. Pull-test a sacrificial cell first.
➜ Shop Layered Oxide Sodium-Ion 18650 Cells
- In stock in Michigan: Sold in 4-packs so you can prototype on your bench, plus 20-packs and 100-packs when you're ready to build.
Specs above are typical values from the NaCR18650-1.3ER datasheet for the 1,300 mAh batch. The cell currently shipping may differ; always confirm limits (voltage, cutoff, current, temperature) against the datasheet for the batch you actually have before finalizing your BMS settings.