Will 21700 cells replace 18650 cells?

Since Tesla announced the production of 21700 power batteries and applied them to Model 3 models, the 21700 power battery storm has swept across. Immediately after Tesla, Samsung also released a new 21700 battery. It also claims that the energy density of the new battery is twice that of the battery currently in production, and the battery pack composed of the new battery can be charged into the battery capacity with a cruising range of 370 miles within 20 minutes. Facing the 21700 power battery market, ams is ready for it. Plugs such as the XT60 series that can pass 30A have been polished in the market for more than ten years and are widely used in electric vehicles, smart robots, energy storage equipment, etc. In the lithium battery application industry, it is deeply trusted by customers.

　　 Like the 18650 battery, the Tesla 21700 battery is also one of the cylindrical lithium batteries. Among them, “21″ refers to a battery with a diameter of 21mm, “70″ refers to a height of 70mm, and “0″ represents a cylindrical battery.

Tesla takes an initial lead

　　 Tesla launched the 21700 battery not to lead the direction of technology, but actually due to cost pressure. Ams’ quick connector products adopt a multi-customer joint research and development model to reduce costs for customers while ensuring quality.

At the beginning of the Model 3 project, Musk set a price of 35,000 US dollars for this car, but if the original 18650 battery is still used, there will be two results, either to ensure that the battery life exceeds the price, or to ensure that the price is reduced. Endurance is difficult to accept for the “picky” Musk. So the question is whether there is a battery that can reduce costs while ensuring battery life. The answer is 21700 batteries.

Although the 18650 battery made great contributions to Tesla’s rise, Musk himself has always been skeptical about it. Regarding the 21700 and 18650 batteries, Musk said on social media: The emergence of the 18650 battery is completely a historical accident. The standard of early products, now only 21700 batteries can meet the battery performance requirements of electric vehicles.

　　Industry analysts believe that the energy density of 21700-type batteries is higher than that of the well-known 18650-type batteries, and the cost will be reduced after grouping. The choice of 21700 is not because its absolute performance is better than other models, but the result of a comprehensive balance of physical properties and economy.

It is reported that the energy density of this 21700 battery system is about 300Wh/kg, which is more than 20% higher than the 18650 battery energy density used in the original Model S. The cell capacity is increased by 35%, while the system cost is reduced by about 10%. Musk said: This set of 21700 batteries is currently the battery with the highest energy density and the lowest cost among mass-produced batteries.

　　 The advantages are obvious, but the disadvantages are worthy of vigilance

　　 21700 battery has three advantages. The energy density of both the single cell and the group has been greatly improved. Taking 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 3~4.8Ah, which is a substantial increase of 35%. After the group, the energy density is still increased by 20%.

　　Because of the higher energy density of the cells, the number of battery cells required under the same energy can be reduced by about 1/3. While reducing the difficulty of system management, it will also reduce the number of metal structures and electrical accessories used in the battery pack. Due to the reduction in the number of monomers used and the reduction in the use of other accessories, the weight of the power battery system is essentially optimized under the premise of ensuring the same capacity. 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.

　　Since the size of the cell can be made larger and the capacity of the cell can be increased, why not use a cell with a larger size and capacity?

　　 Generally speaking, the increase in the physical size of the cylindrical cell will not only increase the energy density, but will also reduce the cycle life and rate of the cell. According to estimates, for every 10% increase in capacity, the cycle life will be reduced by about 20%; the charge and discharge rate will be reduced by 30-40%; at the same time, the temperature of the battery will rise by about 20%.

If the size continues to increase, the safety and adaptability of the battery cell will be reduced, which will invisibly increase the potential safety hazards and design difficulties of new energy vehicles. This is why larger cylindrical batteries such as 26500 and 32650 have not been able to occupy the mainstream market on a large scale. the reason.

　　Theoretically, compared to the 18650 battery, the 21700 battery has a shorter life, longer charging time with the same capacity and lower safety. For electric vehicles, safety is always the first priority. In order to avoid fires due to excessive temperature rise of large batteries, the battery cooling system must be designed more reasonably. At the same time, it is very important to choose a reasonable and high-quality 21700 battery plug. The 21700 lithium battery interface of Ams uses V0 flame retardant materials such as PA66, which is resistant to high and low temperatures. The metal parts use a cross hollow design and good heat dissipation performance. It is the 21700 lithium battery connector. The best choice.

Can 21700 replace 18650?

　　 Judging from the national guidelines for the energy density of power lithium batteries, in 2020, the energy density of power battery cells will exceed 300Wh/kg, and the energy density of power battery systems will reach 260Wh/kg. However, the 18650 battery cannot meet this technical requirement, and the density of most domestic batteries is between 100~150Wh/kg.

Under time-limited conditions, product model improvement is much faster than material progress, so the 21700 battery, which increases the energy density by increasing its volume, will inevitably become a key consideration for enterprises. Coupled with Tesla’s huge industry influence, this battery is likely to become the next cylindrical battery development trend. However, it is difficult to determine whether domestic companies will deploy 21700 batteries as they did before with 18650 batteries. And the 18650 battery has a long history of development and has a strong adaptability. In addition to being used in the field of electric vehicles, it can also be seen in other fields such as notebook computers, 3C digital, drones, and power tools.

　　 For the 21700 lithium battery, there is no effective industrial chain, which will undoubtedly increase the cost and hinder the promotion progress. In this regard, Tesla’s solution is to start large-scale production in a gigabit factory, holding an order of about 500,000 Model 3, and with the huge demand for Sun City, Tesla is enough to digest the output. But this method is limited to Tesla, which is difficult for most other manufacturers.

Moreover, the domestic power battery market has only slowly expanded in recent years. Most of the production lines are set up for the production of 18650 batteries, and even some companies’ production capacity in the next few years will be prepared for 18650. It can be seen that the industry is The 18650 battery is still optimistic for a long time. And in the promotion of 21700 batteries, the country’s relevant policies on battery size standards are the key to determining the fate of 21700 batteries.

　　 No matter what, the new energy vehicle market is advancing rapidly, and the end consumer market has an urgent need for battery life. It determines that manufacturers will give priority to high-density batteries with better overall performance, and policies are also adjusted for market changes.

　　 Today, Tesla has taken the lead to enter the 21700 battery battlefield. Some domestic battery manufacturers choose to follow, and some are still waiting. This may be a gamble or a feast.