2025.06.17
As the demand for high-performance rechargeable batteries continues to surge across various industries—from electric vehicles to smart energy storage—21700 lithium-ion batteries have emerged as a game-changing innovation. But what exactly is a 21700 battery, and how does it compare to other common battery types like the 18650? In this article, we’ll explore the basics, advantages, applications, and why Zigong JOINSUN Technology Co., Ltd. is a trusted supplier in this evolving battery market.
A 21700 battery is a lithium-ion rechargeable battery with a 21mm diameter and 70mm length—hence the name 21700. Compared to the older 18650 battery (18mm x 65mm), the 21700 format offers higher capacity, improved power density, and better energy efficiency, making it ideal for demanding, high-drain applications.
The 21700 cell stands out due to its standardized dimensions of 21mm in diameter and 70mm in length. These measurements make it larger than the widely used 18650 cell, which measures 18mm by 65mm. This increase in size allows the 21700 to deliver higher energy storage and improved performance.
| Specification | 21700 Cell | 18650 Cell |
| Diameter | 21 mm | 18 mm |
| Length | 70 mm | 65 mm |
| Nominal Voltage | 3.6 – 3.7 volts | 3.6 – 3.7 volts |
| Capacity | 4,000 – 5,000 mAh | 2,500 – 3,500 mAh |
| Energy Density Increase | 2% – 6% | N/A |
| Discharge Rate | 3.75c | N/A |
The larger size of the 21700 cell enables it to store more energy, making it ideal for applications requiring high power capacity, such as electric vehicles and industrial battery packs. Its dimensions also contribute to better thermal management, ensuring safer and more efficient operation. Contact us for more details and quotations.
The 21700 battery operates at a nominal voltage of 3.7V, with a full charge voltage of 4.2V and a discharge cutoff voltage of 3.0V. This voltage range aligns with industry standards for lithium-ion batteries, ensuring compatibility with various devices and systems.
| Specification | Value |
| Full Charge Voltage | 4.2V |
| Nominal Voltage | 3.7V |
| Discharge Cutoff Voltage | 3.0V |
| Typical Capacity | 5000mAh or more |
| 18650 Maximum Capacity | 3500mAh |
The capacity of the 21700 battery, ranging from 4,000mAh to 5,000mAh, significantly surpasses that of the 18650 cell. This higher capacity allows the 21700 to power devices for longer durations, reducing the need for frequent recharging. Whether you’re designing a medical device, a robotics system, or a security system, the 21700 battery offers the reliability and endurance you need. Buy now.
The 21700 battery utilizes advanced lithium-ion chemistry, which provides a balance between energy density, safety, and longevity. Depending on the specific chemistry, such as NMC or LCO, the energy density of the 21700 ranges from 250 Wh/kg to 300 Wh/kg. This makes it a preferred choice for applications requiring compact yet powerful energy storage solutions.
For example:
·NMC Lithium battery: Energy density of 160–270 Wh/kg, cycle life of 1,000–2,000 cycles.
·LCO Lithium battery: Energy density of 180–230 Wh/kg, cycle life of 500–1,000 cycles.
The high energy density of the 21700 battery enables it to store more energy in a smaller footprint. This feature is particularly beneficial for consumer electronics and infrastructure projects, where space and weight are critical considerations.
The 21700 cell weighs approximately 60–70 grams, depending on the manufacturer and specific chemistry. While slightly heavier than the 18650 cell, this weight increase is justified by its higher capacity and energy density. The robust construction of the 21700 ensures durability, making it suitable for demanding environments such as industrial applications and transportation systems.
Its durability also extends to its cycle life, with some chemistries like LiFePO4 offering up to 5,000 cycles. This longevity reduces the total cost of ownership, as you won’t need to replace the battery as frequently. For businesses relying on battery packs for critical operations, the 21700 provides a reliable and cost-effective solution.
While both batteries use the same lithium-ion chemistry, 21700 batteries outperform 18650s in several key areas:
·Higher Capacity: Store more energy in the same amount of space.
·Better Power Efficiency: Ideal for high-load applications like electric bikes and power tools.
·Longer Life Span: More charge/discharge cycles over time.
·Improved Thermal Management: Better heat dissipation under heavy use.
At Joinsun, our 21700 cells are engineered for durability, offering excellent cycle performance, overcharge protection, and low-temperature operation, making them suitable even for extreme environments.
Joinsun’s 21700 batteries are widely used in:
·Electric Bicycles & Scooters
·Power Tools (Cordless drills, saws, etc.)
·Electric Agricultural Equipment
·Electric Toys
·Military Radios and Tactical Devices
·Household & Outdoor Energy Storage
·Low-altitude Aerial Devices
·Low-speed Electric Vehicles (LEVs)
These batteries are designed to deliver high discharge rates and long-lasting power for critical applications, contributing to improved efficiency and lower operational costs.
Zigong JOINSUN Technology Co., Ltd. is a trusted name in lithium-ion power battery manufacturing. With over a decade of R&D experience, we operate the Zigong Lithium-ion Battery Technology Research and Development Center, and have built a strong technical team of 33 experts, including 4 industry doctors.
At Joinsun, we supply various cylindrical lithium-ion cells to match different voltage and current requirements:
| Cell Type | Size (mm) | Capacity (mAh) | Typical Application |
| 18650 | 18×65 | 2000–3500 | Portable electronics, LED lights |
| 21700 | 21×70 | 4000–5000 | E-bikes, power tools, solar storage |
| Custom Packs | Varies | Customizable | Industrial & military power systems |
Learn more about our full product range at Joinsun's Battery Catalog.
✅ High Capacity & High Rate Discharge
✅ Excellent Safety Performance
✅ Environmentally Friendly Chemistry
✅ Custom Solutions Available
✅ Compliance with International Standards
We currently offer nearly 20 models of 18650 and 21700 cells, and provide OEM/ODM support for different application needs. Whether you're upgrading your power tools, designing an electric bike, or developing smart storage systems, 21700 batteries offer the power, performance, and longevity you need. With cutting-edge production facilities and a commitment to quality, Joinsun is your go-to partner for advanced battery technology.
Explore our full range of 21700 lithium-ion batteries and custom battery pack solutions. Contact Us Today to get a free quote or technical consultation.
A: The 21700 battery is larger (21x70mm vs. 18x65mm), has a higher capacity (up to 5000mAh), and better energy density, making it more suitable for high-drain devices.
A: Yes. Joinsun’s 21700 batteries are built with multiple layers of safety protection, including overcharge, short-circuit, and thermal safeguards.
A: Only if your device supports the 21700 size. Check compatibility before swapping batteries.
A: The lifespan of a 21700 battery is generally measured in charge cycles, which refers to the number of times the battery can be charged and discharged before it starts to lose capacity. On average, a 21700 battery can last between 500 to 1000 charge cycles, depending on its chemistry, usage, and maintenance. To maximize the lifespan of your 21700 battery, avoid deep discharges (below 20% charge) and overcharging (above 100%). Proper storage at moderate temperatures also helps ensure a long lifespan.
A: Absolutely. We offer OEM/ODM services for custom voltage, shape, or connector requirements.
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