Why is the 18650 power battery pack a new energy vehicle?

    The 18650 battery is an early, mature and solid lithium-ion battery, which is widely used in electronic products. In comparison, laminated lithium-ion batteries are far from mature. Common batteries include square batteries, soft-pack batteries, and even uneven size and ear position. The production 

    process of battery manufacturers is not satisfactory. Most of them depend on the control of human beings. The consistency of the battery is lower than that of the 18650 battery. If the consistency of the battery is not in line with the requirements, the treatment of a large number of battery series and parallel batteries will not allow each battery to function better. The 18650 center may solve this problem.

    In some cases, the monomer capacity of the 18650 battery is small, and the number of monomers required is 7104 (S type), but the compatibility is very good. The capacity of cascade batteries may be very large (the number of monomers is reduced from 20Ah to 60Ah), but the consistency is poor. In comparison, it is difficult to invest a lot of manpower and material resources with battery suppliers to improve the production process of cascade batteries at this stage. Therefore, when developing Roadster and ModelS, Tesla's choice is to buy batteries from the market and develop its own battery system. It should not be difficult to develop a battery system with good consistency of more than 6,000 units and poor consistency of more than 6,000 units. Even if the number of individual batteries increases, if the function of these batteries is strong, it will be easier to manage.

    Compared with another victorious all-electric vehicle - Nissan Leaf - it uses cascade lithium-ion batteries. This is because Nissan has been cooperating with NEC for many years, and has accumulated a large amount of battery skills and energy in the quality control area. Ye's battery comes from AESC-a joint venture between Nissan and NEC. The laminated battery is thin in thickness, large in name, uniform heat dissipation, and good heat dissipation. Therefore, Nissan blades are very brave to adopt a passive heat management system (in fact, not a governance system!) to take away the heat through natural convection air.

    Energy density - In terms of the energy density of a single battery, 18650 batteries are higher than overlapping lithium-ion batteries. The energy density of the 33 Ah lithium-ion battery used by Nissan LEAF is 157 Wh/kg, the energy density of the overlapping battery used in GM Volt is about 150 Wh/kg, and the energy density of the 18650 battery is about 211 Wh/kg at the speed of the sports car. However, the governance system of the 18650 battery is more complicated, so the rated component will make the energy density of the battery pack much lower than that of the monomer. Roadster's battery pack has a component of 450 kg and an energy density of 118 Wh/kg, while the LEAF battery pack weighs 225 kg and an energy density of 107 watts/kg. At the battery level, the energy density of the two is commensone.

    The insurance above introduces the advantages of cascade lithium-ion batteries, but there are also some problems. Because laminated lithium-ion batteries are usually packaged with aluminum-plastic film, the thickness of aluminum-plastic film is thin and the mechanical strength is poor. In the case of car collisions, it is easy to cause aluminum-plastic film damage, causing insurance accidents. This also explains why Nissan needs to add an aluminum shell to the four battery modules. Some 18650 batteries are steel cases with good insurability. As mentioned above, with the improvement of the production process of 18650 batteries, the insurability has also been improving.

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