The magical theory of 21700 cylindrical batteries

In early 2017, during a meeting with investors Tesla announced and Panasonic joint research and development of the new 21700 batteries start mass production, Tesla said the battery will be Giga factory super battery factory production, and to emphasize this is currently in the production of cylindrical batteries energy density is highest and the lowest cost of the product. Then, the domestic enterprise poured into 21700 armies:

On June 28, hundred million weft lithium can announce its 21700 battery products of Hubei province jinquan rolled off the production line, in 2019 officially put on the market;

July 3, intelligent energy formally announced its 21700 battery production plans, wisdom energy will be the construction of six new 21700 product lines;

On July 20, Suzhou listens gwh21700 capacity of 4Power battery The project officially put into production.

For the performance of battery material limit, by increasing the volume to increase the energy density becomes the object of enterprise key consideration; Cylindrical battery, however, the physical size of increase at the same time can also reduce the cycle life, ratio and security; Although for a production18650 battery Changes to the enterprise, production line of general production cost is low, but the increase of cell size is not a long-term solution.

21700 what is the magical place

The difference between 21700 and 18650 battery is the most intuitive is the size bigger.

Because of the limitation of battery materials performance by increasing the volume to increase the energy density becomes the object of enterprise key consideration. Clearly put forward to in our country in 2020, power battery monomer energy density breakthrough 300 WH/kg, power battery system energy density of 260 WH/kg; Power battery system energy density 2025 to reach 350 WH/kg. Power lithium battery Continue to improve the energy density of demand is bound to continue to boost the power The lithium battery Models of change.

Earlier this year, Tesla disclosure of information, under the existing conditions, the production of 21700 battery energy densities of 300 WH/kg, than the original 18650 battery system 250 WH/kg increase about 20%.Battery monomer battery capacity of ascension means that equal the number of batteries required under around a third less energy, reduces the difficulty of system management, since such a simplified metal fittings such as number of elements, although the weight of the single batteries and cost increased, but the weight of the battery PACK and cost reduction.

The bigger the battery really better?

"Large" battery is the result of physical and economy comprehensive balance.

Cylindrical battery, researchers have said more than the physical size increase energy density, at the same time can reduce the cycle of life and properties, such as ratio. According to estimates, every 10% increase capacity, battery cycle life reduces about 20%;Charge and discharge rate by 30 ~ 40%;At the same time the rise of temperature of the battery will be around 20%.Size continues to increase, will face the sacrifice safety risks, that's why the 26500, 32650 cylindrical battery failed to scale occupying power battery such as the cause of the mainstream market.

On July 12, the state administration of quality supervision, inspection and quarantine, the national standardization management committee approved the electric car with three power batteries related standards, including GB/T34013-2017 "electric car with size of power battery products, will be brought into effect on February 1, 2018.

But, according to the requirements for the size in the draft in October 2016, 21700 battery is not within this standard. Therefore, in order to standardize the market order, and also need to close department need of revision of the standard file accordingly.

In 21700, the domestic enterprise

So far, domestic weft lithium can, the wisdom of energy and Suzhou listen have layout 21700 battery products. Suzhou power, said god in conference at the end on the project, including the basic Changzhou, Nanjing jinking, donging steam, Shanxi heavy truck, Jiangsu the Langkawi, Johnson controls, 10 domestic and foreign automobile enterprise and listen company signed a strategic cooperation letter of intent, intention to purchase amount more than $5 billion. It seems the domestic market to accept this technology breakthrough.

At present, the domestic production line of battery enterprises basically is given priority to with 18650 columns, production line transformation mainly involves in the back of the cutting, winding, assembling, into, in view of the semi-automatic line mold adjustment cost is low. Battery manufacturers by the transformation of the mainstream of the original 18650 to 21700 is relatively convenient, not too high investment cost, technical and new investment in equipment, meter 21700 battery will likely usher in growth in the future.

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