12v 18650 battery pack.Advantages of 18650 battery and 21700 battery

With the development trend of new energy vehicles in recent years, lithium batteries have also become popular.

The most widely used cylindrical lithium-ion batteries now include 18650 batteries and 21700 batteries.

18650 lithium battery:

18650 lithium batteries originally referred to nickel-metal hydride batteries and lithium-ion batteries. Because nickel-metal hydride batteries are less used now, they often refer to lithium-ion batteries. 18650 is the ancestor of Kaishan lithium-ion battery - a standard lithium-ion battery model originally established by Japan's Sony Corporation in order to reduce costs. 18 of them are 20mm in size, 65 in length are 65mm, and 0 are cylindrical rechargeable batteries. Common 18650 rechargeable batteries are lithium-ion batteries and lithium iron phosphate batteries.

In terms of 18650 rechargeable batteries, it is necessary to mention Tesla Motors, which has detected many types of rechargeable batteries in the development and design of pure electric vehicles, but ultimately locked on the overall goal of 18650 rechargeable batteries and used 18650 Lithium-ion is a key technology for new energy electric vehicles. It can be said that in addition to the technical nature of the electric motor, Tesla electric motors can generally have no less than the battery of a traditional gasoline car, as well as Tesla's excellent new battery. So why does Tesla choose 18650 rechargeable batteries as its driving force?

Advantage

High consistency of processing technology

Before entering the new energy vehicle industry, 18650 rechargeable batteries have been widely used in electronic equipment. They are the first, most complete and most stable lithium batteries. After years of accumulated experience, Japanese manufacturers have accumulated 18650 rechargeable batteries in consumer products in the automotive battery industry. Excellent technical applications. Konka is one of the world's new batteries and large companies. Compared with other manufacturers, the disadvantage of the product is at least large-scale operation, which is also conducive to the selection of consistent batteries.

In contrast, other rechargeable batteries such as its lithium batteries are far from perfect, and many products cannot be unified in specifications, sizes, etc. Overall, the battery is not as consistent as the 18650 battery. If the consistency of the rechargeable batteries is not enough, the management methods of many series and series lithium-ion batteries will not allow the characteristics of each rechargeable battery to be fully developed as soon as possible. The 18650 lithium-ion battery can effectively solve this problem.


High safety factor

18650 lithium battery has a high safety factor, no explosion, no ignition; non-toxic, non-polluting, passed ROHS brand certification; heat-resistant, 65-degree standard charging and discharging efficiency is 100%. And the choice of aluminum alloy casing can avoid production safety accidents under the influence of extreme conditions, with a high safety factor. In addition, each 18650 rechargeable battery module is small in size, and each module has a certain kinetic energy operating range. Compared with large rechargeable battery modules, it can reasonably reduce the harm caused by common faults.

High energy density

The capacity of 18650 lithium-ion battery is generally between 1200mah-3600mah, while the average battery capacity is only 800mah. Its capacity is 1.5-2 times the net weight of nickel-metal hydride rechargeable batteries, and the life of lithium-ion batteries is very low. Currently, considering Tesla's high mileage requirements, the specific energy of the 18650 lithium-ion core can reach the 250wh/kg level.

Low cost and high performance price

The 18650 lithium-ion battery has a long service life, more than 500 times that of all normal applications. The 18650 product has a high level of technical perfection, the overall design and production technology also has production and manufacturing machinery and equipment, and its derivative 18650 touch group has perfect technology, which reduces its operating and maintenance costs.

At present, 18650 rechargeable batteries have been widely used in the development trend for many years. Compared with other types of new batteries, although they are relatively complete, they still face problems such as high production heat, complex combinations, and the inability to complete fast charging. In this case, the 21700 cylindrical three-dimensional battery should be born.

On January 4, Tesla announced that the new 21700 rechargeable battery developed in cooperation with Kangjia has just begun mass production and is currently working on becoming the largest and cheapest rechargeable battery.

21700 battery:

Rechargeable battery 21700 is a type of cylindrical battery, which actually means: 21- refers to the diameter of the cylindrical battery is 21mm; 700- refers to the aspect ratio of the cylindrical battery is 70.0mm.

Combining the regulation of long-range electric vehicles, a new rechargeable battery model is developed to improve the reasonable utilization of rechargeable batteries. For the same raw material, the volume of 21700 can be 35% higher than that of ordinary 18650 cylindrical lithium ions. The contact parts of the ames21700 lithium power plug are designed with copper rods, which have strong resistance to transient operation and large current carrying capacity.


The new 21700 has four distinct advantages:

(1) The volume of rechargeable batteries increases by 35%. Taking the 21700 rechargeable battery produced by Tesla Motors as an example, from 18650 to 21700, the energy of a single battery can be increased by 34.8ah, an increase of 35%.

(2) The specific energy of the battery system is about 20% higher. According to data released by Tesla Motors, the 18650 rechargeable battery system was originally used for 250wh/kg energy, and the 21700 rechargeable battery system was used for 300wh/kg energy. The volume ratio of the 21700 rechargeable battery is nearly 20% higher than the original 18650.

(3) System software costs are estimated to be reduced by 9%. According to statistical analysis of battery price data released by Tesla Motors, the market price of the lithium-ion battery system powered by the 21700 battery is $170/wh, while the market price of the 18650 battery system is $185/wh. Using 21,700 rechargeable batteries on Model 3 can only reduce system costs by about 9%.

(4) The net revaluation of system software is reduced by 10%. The total capacity is more than 21,700. As the unit volume increases, the unit energy ratio increases. The total number of batteries required for the same kinetic energy can be reduced by about 1/3. The total number of metal components and electrical components selected for the battery pack can reduce the difficulty of the management information system. coefficient. After converting Samsung's SDI to the new 21700 rechargeable battery, it was found that the system was 10% lighter than the existing battery.

The 18650 rechargeable battery has high reliability and stability, and the performance of the 21700 battery is much higher than that of the 18650. In addition, compared with other battery models, the raw materials, processing technology and technical steps of the 21700 rechargeable battery are more advanced than the 18650 rechargeable battery level. Therefore, the 18650 and 21700 production lines are the best match. Some companies are more suitable to work under the production line, and the production lines match 21700 and 18650.