22 Years' Battery Customization
Mar 23, 2021 Pageview：3360
21700 battery is the latest cylindrical lithium battery standard developed by Tesla Motors in the United States and Panasonic in Japan:
21700 is the type of cylindrical battery, specifically refers to: 21 for 21mm battery outer diameter; 70 for 70mm height, 0 for cylinder shape.
The initial research and development of 21700 lithium battery was for the usage of electric vehicles. Therefore, in order to adapt to the requirements of electric vehicles for longer duration and improving the effective utilization rate of vehicle battery space, the single capacity of 21700 battery can reach 3~ 4.8Ah, which increases 35% compared with 18650.
21700 battery also has a qualitative improvement in energy density compared to 18650. The energy density of the early 18650 battery system was about 250Wh/kg, and the later 21700 battery system was about 300Wh/kg, which was nearly 20% higher than the original 18650.
The weight of the 21700 battery is expected to drop by about 10%. Although the overall volume of 21700 is larger than 18650, after capacity improvement, the single battery energy density is higher. The same energy needed for the single battery can reduce about one third to reduce the difficulty of system management, and decrease the number of the battery package metal structure and electrical fittings, which further reduces the weight of the battery. When Samsung SDI changed to a new 21700 battery, it found that the system was 10% lighter than the current battery.
The anode materials of 21700 lithium battery are mostly ternary materials. Currently, NCM811, namely Ni-Co-Manganate 811 lithium battery, is adopted in 2018 with 21700 shape. It is used by Tesla first, then the whole world. People tend to use the circular lithium battery of 811, a ternary anode material. China's 21700 battery has also started to follow up. In 2018, Intelligent Energy said its subsidiary, Far East Foster, had entered the trial production stage and used 811 ternary materials to improve the energy density of 21700. Mass production of the 21700 lithium battery is expected to begin in September 2018.
The 21700 lithium-ion battery, which has increased 35 percent capacity than existing batteries, can be widely used in power tools, electric bikes, laptops and other devices. It will become the new standard for cylindrical batteries.
The widely used 18650 battery has a development history for many years. Compared with other types of battery, it has relatively mature technology, but still faced with issues such as high heat production, complex grouping and inability to realize fast charging. In this context, 21700 cylindrical ternary battery came into being. Comparing with the common 18650 cylindrical lithium battery with the same material, the energy density of the 21700 battery increase by over 20%, the monomer capacity increase by 35%, and the system cost decrease by about 9%.
| Type | Diameter(mm) | Height(mm) | Single battery capacity (mAh) | single battery weight(g) | energy density (Wh/kg) | battery system cost ($/KWh) | battery system price ($/KWh) |
| 18650 | 18 | 65 | 2200-3600 | 45-48 | 250 | 171 | 185 |
| 21700 | 21 | 70 | 3000-4800 | 60-65g | 300 | 155 | 170 |
Take Tesla 21700 battery as an example, after switching from 18650 model to 21700 model, the capacity of single battery can reach 3 ~ 4.8Ah, which increase 35%.
According to the data disclosed by Tesla, the energy density of the early 18650 battery system was about 250Wh/kg. Later, the energy density of the Tesla 21700 battery system was about 300Wh/kg, and the volume energy density of the 21700 battery was nearly 20% higher than the original 18650.
Based on the battery price information disclosed by Tesla, the power lithium battery system of the 21700 battery sells for $170 / Wh, while the 18650 battery system sells for $185 / Wh. With the 21700 battery on the Model3, the cost of the battery system will reduce by about 9%.
The overall volume of 21700 is larger than 18650. As the single battery capacity increase, the single battery energy density is higher, so under the same energy, single battery needed number may reduce one third. It decreases the difficulty of system management, and also reduces the number of the battery pack metal structure and electrical fittings, which further reduces the weight of the battery. When Samsung SDI switched to a new 21700 battery, it found that the system was 10% lighter than the current battery.
The high reliability and stable performance of the 18650 battery is maintained, and the performance of the 21700 battery is greatly improved compared with that of the 18650 battery in all aspects. In addition, compared with other battery models, 21700 is similar to the more mature 18650 battery in terms of raw material selection, manufacturing process and technical process. Therefore, most of the production lines of 18650 and 21700 can be compatible, and some enterprises have a more secure way to work on the production line and draw closer to the compatibility of the production line of 21700 and 18650.
The 20700 battery (20mm in diameter and 70mm in height) is manufactured by Panasonic and is aimed at electric mountain bicycle. The 20700 battery was previously reported to be used in Tesla Model3 cars, but Tesla CEOElonMusk later explained that the battery size has been changed to 21mm in diameter and 70mm in height. They also removed the "0" in the number and determined that the battery used to make the Model3 car was' 21-70 ' battery.
The 20700 battery increases in size by about 10 percent, but is 1.33 times larger in volume and energy storage than 18650. Samsung 21700 battery has a nominal capacity of 4750mAh, a rated voltage of 3.6V and a weight of 75g. Most 18650 batteries range in weight from 45 to 48 g. Tesla Straubel and ElonMusk mentioned that 21700 battery uses 40% more energy than 18,650, and it could have a capacity of 4800mAh.
Flat top 21700 lithium battery: no protective board
Button top 21700 lithium battery: with protective board; The top of the protective board is protruding. The protruding part is protective board.
At present, the international enterprises that can mass produce 21700 batteries include Panasonic, Samsung, LG, SONY, Tesla and so on. On January 4, 2017, Tesla announced the mass production of the new 21700 battery jointly developed with Panasonic, and stressed that it is the highest energy density and lowest cost of the current mass production battery. On January 9, 2017, Samsung SDI launched the new 21700 battery with the same specification after Panasonic. LG 21700 battery also will be ready for mass production in 2021.
At present, the domestic representative manufacturers of 21700 battery are Lilishen, BIC, EVE, Mengshi Technology, etc. In addition, Tianchen New Energy, Tianpeng Power, Chuangming New Energy, Intelligent Energy, Zhihang New Energy, DMEGC, Highstar and Anhui Taineng also have layout of 21700 batteries.
| Samsung 40t 21700 | Samsung 30t 21700 | LG Inr21700 M50 | Sony vtc6a 21700 | |
| Brand | Samsung | Samsung | LG | Sony |
| Model | INR21700-40T | INR21700-30T | INR21700 M50 | US21700VTC6A |
| Nominal voltage（V） | 4.2 | 4.2 | 4.2 | 4.2 |
| Nominal capacity（mAh） | 3.6 | 3.6 | 3.63 | 3.6 |
| Discharge current | 35A maximum continue | 35A maximum continue | continuous current 7.275A | 40A maximum continuous current |
| Protection | no | no | no | no |
| Dimension（mm） | 21.1x 70.4 | 21.1x 70.2 | 21x 70.4 | 21.1x 70 |
| Weight（g） | 66.8 | 68.2 | 69.25 | 72.9 |
The 21700 is the best battery for e-cigarettes. It is described as an upgrade to the 20700 and 18650 batteries because it has more capacity and better performance, and can discharge continuously at high current, so it's called the future of lithium-ion batteries for e-cigarettes.
At present, the best 21700 e-cigarette battery is Samsung 30T (INR21700-30T), which is widely used in high power consumption equipment with a capacity of 3,000mAh. The maximum continuous discharge current is 35A.
The 21700 battery charger is a device that charges the 21700 rechargeable battery and provides energy for the storage device. The general 21700 battery charger has a special charge and discharge management circuit. With a variety of safety protection settings, the charger can effectively prevent reverse, short circuit, overcharge and overcurrent, so users do not need to worry about safety issues.
Charging current of each charging slot can be set manually.
High precision refers to voltage source calibration
The battery will stop charging automatically when fully charged.
It has short circuit protection function.
Automatically detect battery and display charging status.
Automatic measurement of battery resistance
Support independent charging of different circuits.
It has good heat dissipation function.
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