18650 Sodium ion Batteries for Sale

18650 Sodium-ion Battery Cell 1300mAh 3.05V | TOB-18650-C-Na

Product Overview and Ideal Applications
The 18650 sodium‑ion battery is a cylindrical rechargeable cell that uses sodium ions as charge carriers instead of lithium. TOB‑18650‑C‑Na delivers a nominal voltage of 3.05 V and a rated capacity of 1300 mAh, providing a drop‑in form‑factor compatible with existing 18650 pack designs while offering several inherent advantages: sodium is abundant and low‑cost, the cell operates reliably from –40 °C to +60 °C during discharge, and its safety performance under abuse conditions (overcharge, short circuit, crush, heating) is outstanding, with no fire or explosion in standard certification tests.

Unlike lithium‑ion cells that require careful shipping at partial state‑of‑charge and face restrictions on air transport, sodium‑ion cells can be discharged to 1.8 V and stored safely, simplifying logistics. The cell’s weight of 36.5 g and standard dimensions (65.2 mm length, 18.35 mm diameter) allow direct replacement of standard 18650 lithium cells in many applications, enabling a seamless transition to a more sustainable, lower‑cost chemistry.

Ideal for:

1. Stationary energy storage systems (ESS) requiring thousands of cycles, wide temperature tolerance, and intrinsic safety.
2. Low‑speed electric vehicles, e‑bikes, and e‑scooters where cost and safety outweigh the need for maximum energy density.
3. Backup power, telecom base stations, and UPS systems that must operate reliably across a broad temperature range.
4. Power tool and garden tool battery packs where high discharge rates (up to 7800 mA) and mechanical robustness are required.
5. Any manufacturer transitioning from lithium‑ion to sodium‑ion for regulatory compliance, supply chain security, or total‑cost‑of‑ownership reduction.

Where Sodium‑Ion 18650 Cells Fit in Battery Pack Design

The TOB‑18650‑C‑Na is a direct replacement for 18650 lithium‑ion cells in most multi‑cell series‑parallel configurations. Because its nominal voltage is 3.05 V (vs. 3.6 V for NMC or 3.2 V for LFP), a 10S sodium‑ion pack will deliver approximately 30.5 V, whereas a 10S lithium‑ion pack typically delivers 36 V. This voltage difference is small enough to be accommodated by minor adjustments to the battery management system (BMS) voltage thresholds and the motor controller’s input range.

The cell’s discharge curve is relatively flat between 3.0 V and 2.0 V, delivering over 95 % of its rated capacity within this window. The end‑of‑discharge voltage of 1.8 V is well below the typical lithium‑ion cutoff (2.5 V), but this deep‑discharge capability is a defining feature of sodium‑ion chemistry: the cell can be fully discharged for storage without damage, which eliminates the “sleep mode” degradation seen in lithium cells kept at low voltage.

Key electrical characteristics relevant to pack design:

• Maximum continuous discharge current: 7800 mA (approximately 6 C based on 1300 mAh) at 25 °C. This high rate capability makes the cell suitable for power‑intensive applications.
• Standard charge method: CC‑CV, 650 mA to 3.95 V, with a 65 mA cut‑off. The charge temperature range (–20 °C to +55 °C) is notably wider than most lithium cells, simplifying thermal management in outdoor applications.
• AC impedance: ≤30 mΩ, ensuring low internal losses and minimal heating during high‑rate discharge.

Electrical and Safety Performance — Why Sodium‑Ion Excels

At first glance, a 1300 mAh cell with a 3.05 V nominal voltage appears to offer a lower energy density than an equivalent 18650 lithium cell (typ. 2600 mAh, 3.6 V). However, sodium‑ion cells are not intended to compete on gravimetric energy density alone. Their value lies in a combination of factors: the raw material cost per kWh is lower; the safety margin is higher, reducing the need for expensive pack‑level protection; and the wide temperature range eliminates auxiliary heating or cooling, which in turn improves system‑level energy density because fewer parasitic loads are needed.

Cycle Life

The standard cycle life test (0.5 C charge to 3.9 V, 0.5 C discharge to 2.0 V, 25 °C) yields ≥1000 cycles before the capacity drops below 80 % of the nominal value. This is competitive with LFP lithium‑ion cells, particularly considering that the sodium cell achieves this without cobalt or nickel.

Low‑ and High‑Temperature Performance

• –20 °C discharge at 1 C: >80 % of nominal capacity. This is a game‑changer for outdoor energy storage in cold climates where lithium cells require pre‑heating.
• +55 °C discharge at 1 C: >95 % of nominal capacity, demonstrating thermal stability.

Safety Performance

The cell has passed the following abuse tests according to the manufacturer’s specifications, all with the criterion “No Fire, No Explosion”:

Mechanical integrity tests (shock, crush, free drop) are also passed without fire or explosion, and the open‑circuit voltage after shock testing remains ≥90 % of the pre‑test value. This level of safety is a direct consequence of the sodium‑ion chemistry, which is inherently less prone to thermal runaway than high‑nickel lithium chemistries.

Key Engineering Advantages of TOB-18650-C-Na

Wide Operating Temperature Range (–40 °C to +60 °C Discharge)

The cell can be discharged at –40 °C without the capacity loss that cripples conventional lithium cells. This eliminates the need for battery heaters in outdoor cabinets, reducing system cost and complexity. Charging is permitted down to –20 °C, which covers most real‑world winter conditions.

Inherent Safety — No Thermal Runaway

All abuse tests (overcharge, heating to 130 °C, short circuit, crush, nail penetration proxy tests) are passed without fire or explosion. This inherent safety simplifies pack design: fewer protective devices, smaller cell‑to‑cell spacing, and potentially lighter enclosure materials, all contributing to a higher pack‑level energy density and lower cost.

1000+ Cycle Life Under Standard Conditions

More than 1000 cycles to 80 % capacity at 0.5 C cycling is competitive with commercial LFP cells. The sodium‑ion chemistry does not suffer from the same manganese dissolution or metal‑dendrite mechanisms that limit some lithium chemistries, leading to a predictable, gradual capacity fade that is easy to model for warranty forecasting.

Drop‑In 18650 Form Factor

The cell dimensions (65.2 mm × 18.35 mm) and weight (36.5 g) are within the standard 18650 envelope, allowing it to be used in existing holders, fixtures, and spot‑welding jigs without modification. This zero‑change mechanical integration accelerates the transition from lithium to sodium.

Deep Discharge to 1.8 V Without Damage

Unlike lithium cells that degrade if discharged below 2.0 V, the TOB‑18650‑C‑Na can be fully discharged to 1.8 V and stored for extended periods without copper dissolution or SEI damage. This makes it ideal for seasonal applications (e.g., agricultural sensors, marine buoys) and for shipping compliance—the cell can be transported at a completely discharged state, classified as non‑hazardous under many regulations.

Low Internal Resistance (≤30 mΩ)

The AC impedance of ≤30 mΩ ensures that the cell generates minimal internal heat during high‑rate discharge, and the voltage sag under load is small. This is important for power‑tool packs where the peak current can approach the maximum of 7800 mA.

Complete Technical Specifications

General Specifications

Standard test conditions

Unless otherwise specified, all tests stated in this Product Specification are conducted at below conditions:

• Temperature :23℃±2℃
• Relative Humidity :65%±20%
• Atmospheric Pressure:86kPa～106kPa

Electrical characteristics

Cell Safety Tests

Mechanical Tests

Visual inspection

There shall be no such defect as scratch, flaw, crack, and leakage, which may adversely affect commercial value of the cell.

Common Questions for Pack Designers

Q1: What BMS voltage thresholds should I use for a 10S sodium‑ion pack?

For a 10S configuration, the recommended settings are:

• Charge voltage limit: 39.5 V (10 × 3.95 V)
• Float voltage: 39.0 V (10 × 3.90 V)
• Discharge cut‑off: 18.0 V (10 × 1.8 V) or slightly higher at 20 V to extend cycle life. Because the cell can be deeply discharged, you may set the warning at 22 V and the shutdown at 20 V. Ensure the BMS balancing current is appropriate for the 650 mA standard charge rate; passive balancing at 50–100 mA is typical.

Q2: Can I spot‑weld nickel strips directly to this cell like I do with lithium 18650 cells?

Yes. The cell casing is standard nickel‑plated steel, fully compatible with resistance spot welding. Use the same welding parameters you would for a low‑impedance lithium cell: 2–3 ms pulse, moderate pressure, and ensure the weld tips are clean. The cell’s AC impedance of ≤30 mΩ is similar to many high‑power lithium cells, so the weld current should be in the typical range. Always perform a peel test on the first samples.

Q3: How should I store these cells for long periods?

Store at 15 °C to 35 °C with the cell voltage at 2.5–3.0 V (the shipping state). For storage longer than 6 months, check the voltage every 3 months. If the voltage drops below 2.0 V, recharge to 2.5 V. The cell can be stored fully discharged (1.8 V) for transport without damage, but for long‑term storage, the mid‑voltage range is optimal to preserve cycle life.

Q4: Is the capacity test result of 1300 mAh guaranteed for every cell?

The rated capacity is 1300 mAh at 0.2 C discharge. The specification allows up to 3 repeat tests if the initial result is below 1300 mAh, indicating that the cell needs full formation cycling to reach maximum capacity. In production runs, the capacity distribution is tightly controlled, but individual cells out of the box may measure slightly lower until properly cycled.

Q5: Can this cell be used in series strings without a BMS?

No. As with any lithium‑based chemistry, series strings require a BMS to prevent over‑charge and over‑discharge of individual cells. Although the sodium‑ion cell is more tolerant to abuse, a BMS is essential for safety and longevity. The BMS should monitor voltage and temperature per cell, especially in packs exposed to the wide operating temperature range this cell supports.

Ready to build a lower‑cost, safer, and temperature‑resilient battery pack? Request a quotation for TOB‑18650‑C‑Na cells, or order evaluation samples to test in your own application. Our application engineers can also assist you with BMS selection and pack design review.

tob.amy@tobmachine.com  |  +86 181 2071 5609

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