When to Use 21700 Battery Manufacture?
Apr. 28, 2025
Your Ultimate Guide to Explore the Battery
In this article, we’ll take a deep dive into the features, specifications, and typical applications of batteries. Whether you are a consumer, a manufacturer, or just someone interested in energy storage solutions, this guide will provide you with all the information you need.
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Part 1. What is a Battery?
A battery is a type of lithium-ion rechargeable cell. The name “” refers to its physical dimensions: it has a 21mm diameter and 70mm length. This makes it larger than the popular battery, which measures 18mm x 65mm. While the may seem just slightly bigger, its larger size provides substantial benefits in terms of energy storage, power output, and overall performance.
The increased size of the battery means that it can hold significantly more energy compared to its smaller cousins. This results in a longer battery life per charge and improved efficiency in many high-demand devices.
One of the standout features of the is its higher capacity and energy density compared to smaller batteries. This allows it to power larger devices, such as electric vehicles and solar energy storage systems, with more reliable performance and fewer recharges.
Part 2. battery size
As mentioned earlier, the battery is 21mm in diameter and 70mm in length. This cylindrical shape is the same as other lithium-ion cells, but the extra length and diameter allow for greater energy storage. To put it into perspective, a typical battery can store 5,000mAh of charge, whereas the more common battery typically holds between 2,500mAh to 3,500mAh.
This size increase directly correlates with performance improvements. Larger batteries can deliver higher discharge rates, which means that devices using batteries can consume energy at a faster rate without significantly reducing the battery’s lifespan.
It’s also worth noting that the battery is widely used in applications that require both high energy density and compact size. Its ability to deliver more power with less weight makes it perfect for energy-demanding applications like electric vehicles and power tools.
Part 3. Chemistry and structure
The chemistry and internal structure of a battery can vary depending on the manufacturer and its intended application. However, most cells are based on lithium-ion (Li-ion) technology, which is widely used across many types of rechargeable batteries due to its excellent energy density and long lifespan.
There are several types of lithium-ion chemistries that could be used within the format:
- Lithium Cobalt Oxide (LCO): High energy density but lower safety and lifespan.
- Lithium Iron Phosphate (LiFePO4): Safer with longer cycles but lower energy density.
- Nickel Manganese Cobalt (NCM): Provides a balance of energy density, cost, and safety.
The internal structure of the battery consists of several key components:
- Anode: Usually made from graphite, this component stores the lithium ions during the discharge process.
- Cathode: Often made from lithium cobalt oxide or similar materials, it releases lithium ions during discharge.
- Electrolyte: A liquid or gel-like substance that allows the flow of lithium ions between the anode and cathode.
- Separator: A non-conductive layer that prevents the anode and cathode from coming into direct contact, thus avoiding short circuits.
While batteries come in different chemistries, they all share a similar basic structure that allows them to provide excellent performance in a wide range of applications.
Part 4. Voltage
The voltage of a battery typically varies between 3.6V to 3.7V when it’s in use. However, the voltage will fluctuate depending on its state of charge:
- Full Charge: The voltage will be around 4.2V.
- Nominal Voltage: The 3.7V is the average voltage at which most of the battery’s charge is used.
- Discharge Cutoff: Below 3.0V, the battery will lose its charge completely and may suffer permanent damage if discharged beyond this point.
The nominal voltage of batteries makes them compatible with most devices that use lithium-ion cells, including electric vehicles, flashlights, and drones. It’s important to understand these voltage ranges when selecting chargers and other accessories.
Part 5. Weight
The weight of a battery typically ranges from 50 to 70 grams, depending on the exact chemistry and the manufacturer. While this weight is heavier than that of smaller batteries, the trade-off is the higher capacity and energy density of the .
For example, an battery might weigh only about 40-50 grams, but because the holds more power, it’s heavier. This makes the battery ideal for use in larger devices that need extended run times, like electric vehicles or power tools, where every extra gram is justified by the performance improvements.
Part 6. Energy Density
One of the key advantages of batteries is their energy density. Typically, batteries have an energy density ranging from 250 Wh/kg to 300 Wh/kg, depending on the chemistry used. This is a notable improvement compared to batteries, which usually offer around 180 Wh/kg to 250 Wh/kg.
The higher energy density of the battery allows for longer use times between charges. It also makes these batteries ideal for devices that require both power and portability. For instance, electric vehicles can use cells to store more energy in less space, resulting in longer driving ranges without increasing the size of the battery pack.
Part 7. cell and pack(battery)
A cell refers to an individual battery unit, while a pack is a configuration of multiple cells connected in series or parallel. The pack is typically what you find in larger, power-hungry devices like electric vehicles or solar energy storage systems.
- Series Connection: This method connects cells end to end to increase the total voltage. For instance, a 3.7V cell connected in series with another would provide a 7.4V pack.
- Parallel Connection: Cells are connected side by side to increase the overall capacity (mAh). This increases the total energy storage without affecting the voltage.
- Series-Parallel Combination: This is the most common method, where cells are arranged in both series and parallel to achieve the desired voltage and capacity.
To safely operate a pack, it’s crucial to use a Battery Management System (BMS). The BMS monitors the voltage, temperature, and charge cycles of each individual cell within the pack to ensure safe operation.
Part 8. Typical applications
The battery is used in a variety of high-demand applications, including:
- Electric Vehicles (EVs): Due to their high energy density and longevity, batteries are being adopted by companies like Tesla for use in their vehicles. These batteries help provide longer driving ranges between charges.
- Power Tools: Companies like DeWalt and Makita use cells in their cordless power tools for improved runtime and power output.
- Flashlights: High-performance flashlights use cells for extended run times, allowing users to operate lights for hours on a single charge.
- E-cigarettes (Vaping): The battery is favored in high-wattage e-cigarettes due to its ability to deliver high current.
- Drones: Drones that require extended flight times and higher power output rely on batteries for their long-lasting power.
Part 9. battery vs
The most significant difference between the and batteries is their size and capacity. The is larger (21mm x 70mm) compared to the (18mm x 65mm), and this size difference allows the to store more energy.
- Capacity: The typically holds mAh or more, while the generally maxes out around mAh.
- Energy Density: batteries have a higher energy density, meaning they can deliver more power for a longer period of time, making them a better choice for high-demand applications.
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vs Battery: What Difference is between them?
Part 10. How long does a battery last?
The lifespan of a 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 battery can last between 500 to charge cycles, depending on its chemistry, usage, and maintenance.
To maximize the lifespan of your battery, avoid deep discharges (below 20% charge) and overcharging (above 100%). Proper storage at moderate temperatures also helps ensure a long lifespan.
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Part 11. Charger, charging and maintenance
When charging your battery, make sure to use a compatible charger designed for lithium-ion batteries. A Battery Management System (BMS) is often required for safe charging, especially in battery packs.
Charging Tips:
- Never leave your battery charging unattended.
- Use a charger with overcharge protection to prevent battery damage.
- Store your battery in a cool, dry place to avoid overheating.
Maintenance Tips:
- Check for signs of wear, such as swelling or leakage.
- Regularly clean the battery terminals to ensure proper connections.
- If the battery is not used for an extended period, store it at 40-60% charge.
Part 12. Ufine battery
Ufine, a leading Chinese manufacturer of lithium batteries. They’re known for customizing battery shapes, sizes, capacities, and voltages. Whether you need lithium polymer, cylindrical, or LiFePO4 batteries, Ufine has you covered.
Their batteries are reliable and high-quality, catering to various power needs. If you’re looking for a battery that fits your specific requirements, Ufine is a great option to consider. They combine innovation with practicality, ensuring you get the best power solution for your devices.
Lithium Battery Cell Models and the Industry Shifts vs.
Lithium Battery Cell Models and the Industry Shifts vs
By Anton Beck, Battery Product Manager
Epec Engineered Technologies
The lithium battery industry has undergone great strides to meet the ever-increasing power demands of electronics and equipment. These batteries are found in power tools, cars, medical devices, and a range of other machines. Many different sizes and shapes of lithium batteries were being produced during the past two decades as demand fluctuated.
Cylindrical cell models come in a number of sizes as their popularity has caused massive growth in production. Several cell models are available, however, the two that are competing head-to-head when it comes to size and capacity are the vs. models (Figure 1).
Figure 1: Example of lithium battery cell models vs .
Battery Cell Basics
The battery cell model became the most optimized lithium battery to be produced in , although it has been around since as Panasonic first debuted this cell. The battery was longer and wider than the standard AA batteries as the numbers designate the cell model’s size. For the , it was 18mm diameter and a length of 65mm. These batteries provide 2,300 mAh to 3,600 mAh capacities and about 3.6 volts to 3.7 volts.
The cells neared a peak reaching , yet then came into new demand with the rollout of electric cars such as the Tesla. The production of drones, medical devices, and mil-aero equipment also required these batteries. In , nearly 2.55 billion cells were produced. The batteries had a good reliability rate and were low in costs to produce per watt hour.
When looking at the current market, many electronics have gone through drastic design changes. Equipment that required greater levels of power was becoming slimmer and flatter, such as tablets and smartphones. While the demand waned in these market sectors, the fear of battery shortages for the electric vehicle, mil-aero, and medical industries caused manufacturers to create an oversupply of these types of cells. However, the increasing power demands of electronics will soon cause a need for cells with greater capacity. Due to this scenario, the cell models may meet this rising demand.
Battery Cell Basics
The cells became introduced in . They were made in a joint effort between Panasonic and Tesla. The battery cell has a dimension of 21mm diameter and 70mm in length. The cells are slightly larger than the and have a higher capacity. These cells have the same nominal capacity of the batteries they were designed to replace, as they still came as 3.6 volts to 3.7 volts. Yet, they have a greater capacity of 4,000 mAh to 5,000 mAh.
The batteries may come protected or unprotected. Protected cells have a battery management system (BMS) for protection and to prevent overheating. Unprotected cells do not have these safety protections. While being available as cylindrical, the batteries may also come as flat and may also have a button-top version. These battery cells were designed to replace the for electric vehicles.
vs. Cell Comparison
When comparing cells to cells (Figure 2), the batteries have a 50% capacity. The cells also have a greater energy density and a discharge rate of 3.75c. Energy density increases are also lower for the as they may range from 2% to 6% depending on the manufacturer's internal construction for the cells.
The charge and discharge rates for both cells are basically similar. There may be higher polarization for the cells, while the cells have lower resistance and stronger heating. When the battery undergoes cycling, the capacity fades for cells and cells are the same.
Figure 2: Dimensional characteristics of the and cell models.
Industry Expectations
Electronics and car manufacturers have looked at the as a suitable replacement for previous lithium cell versions based on their ease of manufacturing as well as the higher capacity options. The design options for these cells are numerous, as they can come as button cells, prismatic cells, and pouch cells. For designs that have higher costs to the manufacturer, such as pouch cells, cost reductions can be obtained with both the cells as well as the cells. In addition, major cost reductions are expected for several years when manufacturing pouch cells as more economical production methods are introduced with the increase and changes in technology.
The benefits of having a battery cell with greater runtime and more capacity will allow the to be a suitable alternative to the . Yet manufacturers will still continue to roll out the cells for various applications that do not require the larger capacity to function and when space requirements force the cell design to be smaller in size than the .
When looking at the manufacturing industry for lithium cells, the need for lightweight batteries with flexible designs and high capacities will remain in demand for the foreseeable future. This increased capacity will force manufacturers to consider how to make changes to the cell models to convert them to without any redesign.
Higher Capabilities
The flexible PCB areas in rigid-flex circuit boards offer a higher range of capabilities than traditional rigid circuit boards with wired interconnects. When the product design requires high-speed signals and controlled impedance (Figure 4), the flexible board can handle the transmission loads effortlessly. The flexible areas can also provide high levels of shielding for EMI and RF interference from either component within the product or from outside sources. Another benefit to rigid-flex circuits is that they work reliably even when being used for applications in harsh environments. The boards have good corrosion resistance, chemical resistance, and UV resistance. They can also handle higher temperatures up to 200°C while being able to dissipate generated heat.
Summary
Many top-tier cell manufacturers are shifting their focus from the historically predominant cell model to the cell model. As more manufacturers move in this direction, the cell designs and chemistries will vary between each company. Selecting the right cell will be dependent on the requirements of the application, the size of the required battery, and other specifications. One of the major design considerations that will become an important factor with battery manufacturing rests with the flat cells. If the same cell performance of a cylindrical cell can be met when forming it into a flat cell design, the market for these cells will rocket forward for decades to come.
In the near future, the demand for cells will continue onward for many mil-aero, medical, and automotive applications. As more cell designs saturate the market, this saturation may cause manufacturers to lower the amount of available batteries when switching over their production line capabilities. Speaking with a battery pack manufacturer like Epec, regarding the design of their cells allows a company to figure out which type of batteries to use currently and what changes may need to be made in the future if a battery cell becomes obsolete.
Need Help Determining the Proper Cell for Your Battery Pack?
From design to production, our team of experienced engineers at Epec is here to help you design a custom battery pack that meets all safety standards and regulations involved with lithium chemistries.
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