Compared with 21700 and 18650, What are the advantages of 21700 ？
(1) The battery cell capacity is increased by 35%. Take the 21700 battery produced by Tesla as an example. After switching from the 18650 model to the 21700 model, the battery cell capacity can reach 3 to 4.8 Ah, a significant increase of 35%.
(2) The energy density of the battery system is increased by about 20%. According to the data disclosed by Tesla, the energy density of the 18650 battery system used in the early days was about 250Wh/kg. Later, the energy density of the 21700 battery system produced by it was about 300Wh/kg. The volumetric energy density of the 21700 battery was higher than that of the original 18650. Nearly 20%.
(3) The cost of the system is expected to drop by about 9%. From the analysis of battery price information disclosed by Tesla, the power lithium-ion battery system of the 21700 battery is priced at US$170/Wh, while the price of the 18650 battery system is US$185/Wh. After using 21700 batteries on Model 3, the cost of the battery system alone can be reduced by about 9%.
(4) The weight of the system is expected to drop by about 10%. The overall volume of 21700 is greater than 18650. As the monomer capacity increases, the energy density of the monomer is higher, so the number of battery monomers required under the same energy can be reduced by about 1/3, which will reduce the difficulty of system management and reduce the number of batteries. The number of metal structural parts and electrical accessories used in the bag further reduces the weight of the battery. After Samsung SDI switched to a new set of 21700 batteries, it was found that the weight of the system was reduced by 10% compared to the current battery.
Maintaining the high reliability and stable performance of the 18650 battery, the performance of the 21700 battery is greatly improved compared to the 18650 in all aspects. In addition, compared with other battery models, the 21700 is similar to the more mature 18650 battery in terms of battery raw material selection, production process and technical process. Therefore, most of the production lines of 18650 and 21700 are compatible. Some companies have a more prudent way to make a fuss on the production line and move the production line closer to the compatibility of 21700 and 18650.
The pursuit of high specific energy for power lithium batteries has become an irreversible trend, and many battery companies have begun to turn their attention to the layout of 21700 batteries. The production lines of some companies are imported from abroad, but the assembly is done by themselves, so the conversion from 18650 to 21700 can be realized at a lower cost.