Lithium batteries were first introduced by SONY. Li-ion is popular in the market due to its high energy density and recyclability. Furthermore, it has greatly promoted the process of human electronic information age.
Due to above reason, lithium ion was chosen as a breakthrough technology of the 20th century.
The performance of lithium-ion safety and fast charging is recited in many electrical appliances.
A comparison of the 18650 Li-ion battery with the 21700 Li-ion battery. There is also a heated debate. Why was the 18650 that Tesla initially used in electric vehicles replaced by the 21700? What are the advantages of the 18650? And what are the main application areas of 21700? Etc…
Here is article will take you to know more.
Let’s go to the topic.
What is 21700 battery?
A “21700 battery” is short-hand for a rechargeable, lithium ion battery that is 21 mm in diameter and 70 mm in length.
This size cell first became popular in electric cars like Tesla and electric scooters.
For now, It is also often used in vaping and flashlights.
What is the advantages of 21700 cells?
About Tesla Model 3, since Tesla’s batteries were changed from 18650cells to 21700 cells, many people have wondered what magic does 21700 have?
Let’s dive on agin.
There are three unique advantage you need know.
Higher total cell capacity.
The battery capacity (measured in milliamp-hours or mAh) of 18650 cells is limited to a maximum of around 3600mAh because of its size.
However, the 21700 battery is able to reach a maximum capacity of 5000mAh – a 42% increase.
For flashlight or e-cigarette users, that means up to 142% of the previous run time on a single charge, which is invaluable for heavy users. And since they’re still less than 1″ in diameter, flashlights using these batteries can still fit in standard 1″ weapon mounts and holsters!
Lower cost per wh
According to Tesla’s disclosed official information, The 21700 lithium battery system costs $155 / kwh ,but the 18650 lithium battery system costs $171/ kwh.
So, the cost of the battery system can be reduced by about 9%, if 21,700 cells are installed on Tesla Model 3.
In fact, we caculate that 18650 needs more raw materials to reach a battery pack of the same capacity, which is also the reason for the higher cost.
For example, a battery with a capacity of 100Ah can be composed of 20units 5000mah 21700 cells, but if using 18650 battery, it needs to consume 30units 3300mah 18650 cells.
Higher battery energy density
According to Tesla’s official disclosures.
The energy density of the 21700 battery is close to 300wh/kg.
The energy density of the 18650 only can only reach 250wh/kg.
In comparison, the energy density of the 21700 battery is nearly 20% higher than that of the 18650.
How to make 21700 cells?
Below is the brief procedure of the the lithium battery cells production. If you want to get more detailed production process of lithium cells, please read article 《What is the production process of the lithium battery cells?.
- 1 Step: Mixing
- 2 Step: Coating
- 3 Step: Pressing
- 4 Step: Slitting
- 5 Step: Tab forming
- 6 Step: Winding
- 7 Step: Vacuum baking
- 8 Step: Tab welding
- 9 Step: Packaging
- 10 Step: Leak test
- 11 Step: Electrolyte injection
- 12 Step: Formation
- 13 Step: Aging
How many types of 21700 cells in the market?
There are main four model are common in the market,
| Model | 21700-4Ah | 21700-4.5Ah | 21700-4.8Ah | 21700-5Ah |
| Voltage | 3.7V | 3.7V | 3.7V | 3.7V |
| Capacity | 4000mah | 4500mah | 4800mah | 5000mah |
| Material | NCM | NCM | NCM | NCM |
The typical application of 21700 cells
Car
Tesla are using Panasonic 21700 5000mah cell for their Tesla model 3 car.
Flashlight
Fenix is a company who produce personal lighting products. Their PD36R Flashlight are specially use 21700 cells. Just as they clarify, when they change 18650 cell to 21700cells, the duration time per battery is greatly improved.
Vaping (E-cigarette)
Electronic cigarettes are not sensitive to cost relatively. Ofcourse, some people are willing to buy vaping that can be used for 142% long time.
Who produce 21700 cells?
There are three famous producers all over the world, LG, Samsung, and Panasonic.
Also you can connect ELB team to have a consultation. This is the link of become a distributor.
ELB Energy Group is the leading supplier and manufacturers of lithium ion batteries situated in China, ELB can provide a market proved 21700 cells all over the world.
What is 18650 battery?
A “18650 battery” is short-hand for a rechargeable, lithium ion battery that is 18 mm in diameter and 65 mm in length.
Due to their superior capacity and discharge rate, they are commonly used in flashlights, laptops, scooters, and high-power-consuming devices.
Tesla Model S are use 18650 cells also.
This size cell first became popular in electric cars like Tesla and electric scooters.
The advantages of 18650 cells?
When the 18650 was originally designed, it is still enduring even now. Many tricycles, scooters, consumer products still use 18650 cells, here is three unique advantage that you may interested.
Better heat dissipation performance
The following picture shows the internal structure of 18650 and 21700. Through comparison, it is found that the winding length and thickness of 21700 are much larger than that of 18650. When the battery is working, 18650 have a better heat dissipatetion performance.
High cost performance & Adequate supply
In 1990, Sony launch 18650 cells.
In 2017, Tesla and Panasonic was jointly launch 21700 cells.
The market expansion of 18650 cells has been going on for 20 years, while, the market expansion of 21700 cells has only been five years.
In the market, there are more than 50 manufacturers producing 18650 cells, while fewer than 10 manufacturers producing 21700 cells.
It also leads to the fact that the 18650 batteries on the market have always been in sufficient supply and at affordable prices.
How to make 18650 cells?
Th production process are basically the same between 18650 cells and 21700cells. Only the “winding” procedure will have a slight difference. The 21700 is fatter and requires more turns. The 18650 is slimmer and requires fewer turns.
If you want to get more detailed production process of lithium cells, please read article 《What is the production process of the lithium battery cells?.
How many types of 18650 cells are there?
Here is the typical 18650 cell model in the market, the capacity are from 2Ah to 3.5Ah.
Also the cycles times are have difference because the production process is different, the cycle life is also different, the lifespan of NCM 18650 cells are roughly 300-1000 times.
| Model | INR18650-2Ah | INR18650-2.2Ah | INR18650-2.5Ah | INR18650-3Ah | INR18650-3.2Ah | INR18650-3.5Ah | IFR18650-2Ah |
| Voltage | 3.7V | 3.7V | 3.7V | 3.7V | 3.7V | 3.7V | 3.2V |
| Capacity | 2000mah | 2200mah | 2500mah | 3000mah | 3200mah | 3500mah | 2000mah |
| Material | NCM | NCM | NCM | NCM | NCM | NCM | LFP |
The IFR18650 is made of LFP material(Lithium iron phosphate material), and the cycle life can reach more than 3,500 times. For detail parameter, you can check the introduction about the cylindrical cells.
The typical application of 18650 cells
- Electric car
- Electric bicycle
- Emergency power light
- Consumer electronics products
- Power tools
Who produce 18650 cells?
Same as the 21700 cells, there are three famous producers all over the world, LG, Samsung, and Panasonic.
Also you can connect ELB team to have a consultation. This is the link of become a distributor.
ELB Energy Group is the leading supplier and manufacturers of lithium ion batteries situated in China, ELB can provide a market proved 18650 cells all over the world.
Which one is better for your application? 21700 or 18650 battery?
After the above comprehensive comparison, I believe that you already knows the advantages/disadvantages of 18650 and 21700 batteries.
For small batch customers, because the number of 18650 manufacturers on the market far exceeds 21700 manufacturers, in order to facilitate more manufacturers to try, Ofcourse, 18650 is the first choice.
If high energy density and compact design space are required, we recommend the 21700.
For your battery design, do you have enough battery space? Under the same battery capacity, what is the cost difference between 18650 design and 21700 design? Welcome to leave a message below, or directly consult the ELB team to obtain quotations and solutions.
Related article
1. Related article 《18650 vs 14500 Battery: Complete Comparison Guide》
2. Related article 《26650 vs 18650 Battery, What Is The Difference?》
3. Related article 《18650 Battery Vs AA Battery: Comprehensive Comparison Guide》
4. Related article 《How Do Lithium Ion Batteries Work?》
5. Related article 《Benefits Of Lithium Batteries》