At the end of July, Tesla released its Model 3, which is claimed to have cruising range of 354 kilometers and 499 kilometers. They may also surprise us with high-performance version later.
Among them, the lowest price of 35,000 USD, so that Model3 has become Tesla’s most affordable price so far.
It is worth noting that the key to enabling Tesla to launch such a civilian-grade electric vehicle is the use of a bolder and longer upgraded battery, the 21700 battery.
Like the 18650 battery, the 21700 battery is also one type of cylindrical lithium batteries: “21” refers to 21 mm in diameter, “70” refers to 70 mm in height, and “0” represents a cylindrical battery.
Tesla made a preliminary lead
Tesla’s launch of the 21700 battery is not intended to lead the technology but is actually under pressure from cost.
So the question is whether there is a battery to reduce costs while guaranteeing battery life.
The answer is the 21700 battery.
Although the 18650 battery made great contributions to the rise of Tesla, Musk himself has been skeptical about it. For the 21700 and 18650 batteries, Musk stated on social media that the appearance of the 18650 battery was completely a historical accident.
It was Early product standards, only 21700 batteries will be up to meet the battery performance requirements of Tesla.
Why is the 21700 battery?
Industry analysts believe that the energy density of the Model 21700 battery is higher than that of the well-known 18650 battery, and the cost will be reduced after the battery pack is made. The choose of 21700 is not its absolute performance superior to other models. It is the result of a balanced physical and economic balance.
Earlier this year, Tesla formally announced that the new 21700 battery jointly developed with Panasonic will start small-scale production, and will start large-scale production and supply of Model 3 at the Giga-scale plant by the end of the year.
It is reported that the energy density of the 21700 battery system is around 300Wh/kg, which is more than 20% higher than that of the 18650 battery used by the original Model S. The capacity is increased by 35%, and the system cost is reduced by about 10%.
Musk said: This set of 21700 batteries is the highest energy density and lowest cost battery currently available for mass production.
Obviously, there are many advantages, but the shortcomings are worthy of vigilance.
The 21700 battery has 3 major advantages.
#1 Both cell capacity and battery energy density are greatly increased. After switching from the 18650 model to the 21700 cell, the battery cell capacity can reach from 3Ah(18650) to 4.8 Ah(21700), a significant increase of 35%. For the whole battery pack, the energy density still increased by 20%.
18650 21700 20700 battery
#2 Due to the higher energy density of the new 21700, the number of required battery cells can be reduced by about 1/3 for the same capacity, which will, therefore, reduce the difficulty of system management and also reduce the number of metal structural parts and electrical accessories used in the battery pack.
Tesla 18650 battery system costs about 171 US dollars/ Wh, after switching to 21700, the estimated cost of the system can achieve about 9% decline, reaching 155 US dollars/ Wh.
#3 Due to the reduction in the number of cells used and the decrease in the use of other accessories, the weight of the power battery system is essentially optimized under the precondition of ensuring the same capacity. After Samsung SDI switched to a new type of 21700 battery, it found that the system reduced the weight by 10% compared to the current battery.
Since the size of the cell can be made larger to increase the cell capacity, why not use a cell with a larger size and capacity?
In general, the increase in the physical size of the cylindrical cell will not only increase the energy density but also reduce the cycle life and the rate of performance of the cell. It is estimated that for every 10% increase in capacity, the cycle life will be reduced by approximately 20%; the charge/discharge rate will be reduced by 30 to 40%; at the same time, the cell will have a temperature rise of approximately 20%.
If you continue to increase the size, the safety and adaptability of the battery will be reduced, invisible increase the potential safety hazards and design difficulties of new energy vehicles, which is why large-size cylindrical batteries 26500, 32650, etc. cannot occupy the mainstream market the reason.
Theoretically, compared with 18650, the 21700 has a shorter battery life, longer charging time and less safety. For electric vehicles, safety is always the first priority. In order to avoid high battery temperature and thus caught fire, the battery cooling system must be designed more reasonable.
Will 21700 Send 18650 into History?
According to the national forecast (China) for the energy density of lithium batteries will exceed 300Wh/kg in 2020, and the battery pack energy density will reach 260Wh/kg. The best 18650 battery currently available does not meet this technical requirement. The density of most domestic batteries is between 100 and 150 Wh/kg.
Within the limited time, the change of the product model is far easier than the new study/invention of battery material. Therefore, the 21700 battery that already increased energy density is bound to be a top consideration.
Given the many advantages of the 21700 battery, coupled with Tesla’s huge industry influence, this battery is likely to become the next cylindrical battery development trend. However, although it is a future trend, it will be difficult to determine whether domestic companies will deploy 21700 batteries as they did in 18650 batteries.
Since the 18650 battery has a long history of development and accumulation, it has a strong adaptability and has formed a large market space and application range. In addition to applications in the field of electric vehicles, it can also be used in notebook computers, 3C digital, drones, power tools See other fields.
For the 21,700 new batteries, there is still no effective industrial chain, which will undoubtedly significantly increase the cost of impending promotion progress. To this end, Tesla’s solution was to start production on a large scale in a Giga-scale plant. He took orders for about 500,000 Model3 units, plus Solar City, which is in great demand. Tesla was able to digest the output. However, this method is limited to Tesla and it is difficult for most other manufacturers.
21700 battery pack
In addition, the domestic power battery market is only gradually developed in recent years. Most production lines are set for the production of 18650 batteries. Some companies even have production capacity for 18650 in the next few years. 18650 battery is still promising.
If these market demands are not obvious and the manufacturing process of the battery companies is a secondary factor that is difficult to promote for the 21700 battery, then the country’s related policy on battery size standards is the key to determining the fate of the 21700 battery.
In the draft of the “Size Specification for Power Battery for Electric Vehicles” formulated by the Ministry of Industry and Information Technology, the currently recommended cylindrical battery models are only 18650 and 32650. If this policy is implemented, it means that the 21700 battery that lead the new energy automobile market is being closed.
A person in charge of a domestic power battery manufacturer believes that the 21700 cylindrical battery will form a trend in the future, but if the country does not explicitly support the battery size standard, the development prospect of this type of battery will not look so good.
In any case, the new energy automobile market is rapidly advancing, and the end consumer market has an urgent need for battery life. It determines that manufacturers will give priority to selecting batteries with high density and better overall performance. The policy is also adjusted for changes in the market.
Today, Tesla is the leader in the battlefield of the 21700 battery. The Chinese battery manufacturers have some choices to follow and some are waiting to see. This may be a gambling or a feast.