Fake it till you make it。
On Tesla Battery Day 2020, Musk proposed a TWh-level battery production target
Many times the first step to do things is to "blow the bull out", in 2020 Tesla unveiled the epoch-making 4680 battery on Battery Day, and only 1 year after the concept of the 4680 battery was proposed, in 2019, Panasonic and a chemistry laboratory in Europe optimized and improved the cylindrical battery based on the theory of the omnipolar ear, and finally felt that the 4680 battery was a good solution.
If you take panasonic's style, at least until 2022 to start publicity, until 2025 may start mass production, after all, the laboratory to make and large-scale mass production is not the same thing, but Tesla just dares to "blow out", and this time it seems to be blown again.
Celebrating the pilot production of 1 million 4680 batteries at Tesla's California factory, which can hold about 1,000 Model Y
At the just-concluded Electric Vehicle 100 People's Meeting 2022, Panasonic, BAK Battery, and Ewell Lithium Energy have expressed their optimism about the 46 series of large cylindrical batteries, and at the same time, in January Tesla announced that it has piloted the production of 1 million 4680 batteries in its California factory, and the official installation of 4680 batteries is close at hand.
The following focuses on the core technological innovation of Tesla's 4680 battery and the future impact on the market.
01
Recognize the 4680 battery
Before introducing the core technology of tesla 4680 battery, let's briefly understand the 4680 battery through a few questions and answers.
What is the 4680 battery?
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The 4680 battery is a cylindrical battery with a diameter of 46 mm and a height of 80 mm, and the 18650 and 2170 batteries currently used by Tesla also conform to this naming convention, in which the last "0" of the 18650 battery has the meaning of cylindrical, but the 2170 and 4680 batteries are omitted.
Why a 4680 battery and not a bigger or smaller battery?
Tesla PPT shows that a cylindrical battery diameter of 46 mm is the optimal solution for endurance increase and cost reduction
First of all, the diameter of "46 mm" this indicator, from the safety point of view, although the number of battery cells in the vehicle can reduce the difficulty of BMS management, but the heat dissipation of large batteries is a problem, 46 mm is a point in the balance range. From the perspective of improving endurance and reducing costs, Tesla believes that the endurance of the vehicle begins to decline after 46 mm, and the marginal benefit of cost reduction becomes very low, so 46 mm is the optimal solution. In addition, from the perspective of internal stress, 46 mm is also a relatively critical point, before there is no essential breakthrough in chemical properties and production processes, 46 mm is a gold size.
Another parameter height of "80 mm", in fact, the industry has not yet determined, mainly due to the chassis design of each company, such as BMW is using the 4695 solution, and some manufacturers have planned the 46105 program, that is, the height is 105 mm. But this height can not be too high, on the one hand, radial heat dissipation will be a problem, on the other hand, this will significantly increase the thickness of the chassis, thereby affecting the design aesthetics and wind resistance.
Why does Tesla love cylindrical batteries?
Simply put, path dependence, Tesla was established in 2004, launched the first model Roadster in 2008, when there was no very mature power battery solution on the market, and Panasonic's 18650 battery in the civilian field has been very mature and stable, safety and consistency have reached a very high level, Tesla then chose to use thousands of single batteries to assemble the program, although the BMS test is relatively large, but at that time it was more reliable than other power battery solutions.
Tesla Model S battery pack, consisting of thousands of 18650 batteries
With the development of power batteries, the 18650 battery is gradually upgraded to a 2170 battery, Tesla and its suppliers Panasonic, LG Chem, etc. are becoming more and more specialized in cylindrical batteries, but this time the 4680 battery is also an upgrade of the squeeze toothpaste for the cylindrical battery.
02
Toothpaste squeeze explosion, the core technological innovation point of Tesla 4680 battery
Tesla Battery Day PPT, 4680 battery than 2170 battery increases battery life by 54% and reduces cost by 56%.
The upgrade from 18650 to 21700 can be seen from the numbers that there is a bit of squeezed toothpaste, a bit like the Qualcomm Snapdragon chip in the past two years, and the 4680 battery compared to the 2170 battery, not only the volume increased by 448%, but more with the full pole ear, high silicon anode, combined with CTC and other revolutionary technologies, and finally there was a 54% increase in battery life, a 56% cost reduction, and a 69% squeeze toothpaste-style increase in the amount of equipment investment per unit of production capacity (of course, Tesla's PPT There has always been some moisture, which should be achieved after two or three iterations of the 4680 battery).
Full polar ears: open far, but also charge fast
Traditional batteries have a very large limitation: energy density and power density can not be taken into account, for example, Honda Accord hybrid ternary battery energy density is only 82 Wh / kg, while the pure electric model of ternary lithium battery energy density is generally 150-180 Wh / kg, this is because the core parameter of heV lithium battery is power density, after all, the battery is small (The battery capacity of the Accord Hybrid is only 1.3 kWh) and it is necessary to drive a high-power motor, which can only sacrifice some mass energy density.
Under the omnipolar ear scheme, the path of electron circulation is significantly shortened
And Tesla 4680 battery by the use of full polar ear (Tesla propaganda is no polar ear) scheme to let the two take into account, the polar ear is simply the contact point when the positive and negative poles are charged and discharged, the traditional battery has a polar ear in the positive and negative electrodes, which brings a problem, when the current flows from the positive electrode to the negative electrode, as shown on the left side of the figure above, to cross a long transverse path, so that the internal resistance naturally comes up, not only the energy of the battery is lost, but the heat problem is difficult to solve.
According to tesla patents, we can see that the positive and negative poles of the 4680 battery are distributed on the positive and negative poles, which greatly shortens the polar ear spacing, such as the 2170 battery electrons flowing through the entire winding pole plate in the collector, the path is about 900 mm, and the positive and negative film of the 4680 is 4-5 times that of the 2170 battery, if the unipolar ear is still used, then the path of the electron will be up to 3.8 meters, and the internal resistance will increase by 4 times, and the full polar ear scheme can shorten this path to the height of the battery , that is, 80 mm, according to Tesla, the heat resistance in the 4680 battery is only one-fifth of the 2170 battery. This, coupled with the fact that the omnipolar ear greatly increases the current path, making it easier for electrons to move inside the battery.
Under V3 overcharge, the 4680 battery is expected to charge faster than the 2170 battery, and the gap is expected to be more obvious under V4 overcharging
According to Insideevs research, the 4680 battery system of 400 V takes 15 minutes to charge 70%, while the Porsche Taycan with the 800 V battery system and the IONIQ of Hyundai take 18 minutes and 22 minutes respectively. In the future, if the 4680 battery uses an 800 V voltage system, the charging speed will be faster.
High nickel cathode + high silicon anode: the key to a monomer energy density of 300 Wh/kg
At present, Tesla's 4680 battery cathode still uses the NCM 811 high-nickel scheme, which is already familiar to everyone, and the future 4680 cathode will evolve to a higher proportion of nickel (such as NCM 9/0.5/0.5) and "cobalt-free" and "quaternary".
There is little change in the positive electrode, and the negative electrode is also critical to achieve higher energy density. At present, the vast majority of batteries are graphite anodes, but the theoretical specific capacity of graphite is 372 mAh/g, which has actually reached about 330-370 mAh/g, which has touched the ceiling. The specific capacity of silicon can reach 4,200 mAh/g, which is more than 10 times that of graphite, so the incorporation of a certain proportion of silicon at the negative electrode has always been the direction of the cell energy density breakthrough.
On the 2020 NIO DAY, the PPT of THE NIO 150-degree battery showed the silicon carbon anode and the high nickel cathode, achieving high energy density
In fact, as early as 2017, tesla on the Model 3 equipped with 2170 batteries (from Panasonic), Tesla has introduced "silicon-doped" technology, but the proportion is still relatively small (about 5-6% silicon alloy), and the increase in energy density is not too obvious. Some domestic manufacturers have adopted the "silicon-doped" negative electrode, such as the CLTC endurance of 1,000 km GAC Aean LX 144.4 degrees Of large battery the negative electrode is mixed with a certain proportion of silicon, in addition to Zhiji Automobile and Weilai's upcoming mass production of 150 kWh "solid-state" batteries in the fourth quarter also use this technology.
Although "silicon doped" can immediately increase the energy density, silicon is not as stable and easy to expand as graphite, generally the carbon-based anode in the lithium-embedded reaction volume expansion does not exceed 10%, while the silicon base can expand by 360%, resulting in side reactions such as SEI membrane damage, resulting in battery capacity attenuation.
Relatively speaking, the stresses inside the cylinder are uniform in all directions
Relatively speaking, the structure of the 4680 battery is more suitable for "silicon-doped", first of all, the characteristics of the cylindrical battery pole winding can be as uniform as possible to make the expansion force of the pole plate at all positions, reduce the appearance of damage and wrinkles, square and soft pack batteries are prone to damage and folds caused by stress concentration at the R angle, and the stainless steel shell of the 4680 battery has a large mechanical strength and can fully absorb the expansion force of the negative electrode. Therefore, in theory, more silicon can be incorporated into the negative electrode of the 4680 battery, and it is expected to reach more than 10%, and the energy density can be significantly improved.
CTC Technology: Born to be a good partner
Starting from the first principle, to improve the energy density of the battery pack, the "middleware" must be as little as possible, for example, if you want to let a box contain the most eggs, it is best to remove the egg tray, which is equivalent to removing the mold components, more extreme, the box is also not wanted, that is, CTC (Cell to Chassis) technology, some are called CTV (Cell to Vehicle).
The 4680 battery is combined with CTC technology, and the seat sits directly above the battery
The 4680 battery is born with this potential, first of all, CTC has certain requirements for the structural strength of the battery, the battery itself has to bear a lot of mechanical strength, compared to the 18650 and 2170 batteries, the 4680 single battery has a higher structural strength, and the general square shell battery is aluminum shell, and the 4680 shell is stainless steel, and the natural structural strength is guaranteed. In addition, the use of CTC technology basically means saying goodbye to repairs and replacements, if there is a fierce collision or a problem with the consistency of the battery, then it may only be possible to change the car, and the consistency of the cylindrical battery has always been the advantage. Finally, compared with the shell battery, the layout of the cylindrical battery will be more flexible, can adapt to a variety of different chassis, combined with the advantages of high energy density and high charge and discharge power of the full polar ear, the future potential in the field of HEV and PHEV is also very large.
In addition to full-pole ear batteries, high nickel + high silicon and CTC technology, Tesla 4680 batteries have other technical applications, such as applying PVDF on the separator to prevent silicon negative expansion, adding silicon nanotubes to the negative electrode to improve conductivity, and Tesla's second-generation 4680 battery may also use the dry electrode process, in short, Tesla is going to squeeze out the toothpaste, depending on how the opponents take the trick.
03
4680 Cylindrical battery VS CTP square battery, NINGDE era is dangerous?
The square battery in the Chinese market is thriving, and the cylinder, square and soft bag in the overseas market stand tall
The data shows that since 2019, the square battery in China's power battery market has occupied about 80% of the share, and the Ningde era accounts for more than half of it, and the first impact of the 4680 battery is also the Ningde era.
Here first put aside the domestic soft pack batteries mainly around European customers such as Mercedes-Benz, focusing on the advantages and disadvantages of CTP square batteries and 4680 cylindrical batteries and development trends.
The layout of the 4680 battery
First of all, the group efficiency of the square battery from the structure is significantly better than that of the cylindrical battery, it is expected that the excellent CTP square battery can reach 80%-90%, 4680 + CTC can reach more than 70%, which is not difficult to understand, although the 4680 battery is much larger than before, but the ratio with the large square battery is still very small, a Model Y needs about 960 4680 batteries, replaced by a square shell may only need 6 to 10 pieces, the less the number, The lower the proportion of other components unrelated to chemicals.
Volkswagen's CTP ternary square battery pack
However, due to the square battery cell is large, and is a surface contact, so that the square battery heat dissipation and thermal runaway protection with a great difficulty, so the square battery ternary battery positive pole is not very suitable for the direction of ultra-high nickel development, at the same time said above that the square battery negative electrode is not suitable for adding too much "silicon", so the square battery's single energy density can not be too high.
The cylindrical battery because the single cell is small, itself is relatively easy to dissipate heat, coupled with the application of the full pole ear so that the heat concentrated below is easier to target the heat dissipation, so you can use a more aggressive high nickel scheme, coupled with high silicon anode, the single energy density can reach 300 Wh /kg, in the future, if the use of more than 90% of the proportion of nickel positive electrode, the single energy density can reach 350-400 Wh/kg.
In this way, although the integration efficiency of the square battery is high, the single energy density of the 4680 cylindrical battery is high, and the system energy density of the two is similar.
As a variety that has been commercialized for more than 30 years, the cylindrical battery has the most mature process and has certain advantages in terms of production efficiency, yield rate, investment cost and so on. For example, in terms of yield, Panasonic's 2170 battery can reach more than 99%, compared to the square battery can reach 90% is already a very good level.
In addition, in terms of production efficiency, if the winding process is also adopted, the innate efficiency of the concentric circle winding of cylindrical batteries is much higher, such as according to the latest production line of Ewell Lithium Energy, 200 2170 batteries can be produced per minute, and the square batteries within 200 Ah of similar production lines can generally produce 10-12 in a minute, and the large square with more than 200 Ah can produce less than 10 per minute. If it's a new car with 80-degree electricity, the production of cylindrical batteries takes about 20 minutes, while the square batteries take 30 minutes.
If the large-scale mass production of 4680 batteries is successful, it is expected that the cost of 4680 batteries per kWh after 2024 will be 50-100 yuan cheaper than that of ternary square batteries, and the cost of an electric vehicle with a 100-degree battery can be 5,000-10,000 yuan lower.
Therefore, from the perspective of the ternary battery system (including cobalt-free batteries and quaternary batteries), if the yield rate of the 4680 battery can be rapidly improved, it will rely on certain cost advantages and ultra-high charge and discharge power, and will gradually form a replacement effect on square ternary lithium batteries in the high-end market.
In the low-end market, lithium iron phosphate batteries are still dominant, and lithium iron phosphate is inherently relatively stable and not easy to get out of heat, so it is more suitable for square batteries with high integration efficiency but not easy to dissipate heat. Therefore, the future situation is likely to be that some high-end models will gradually use 4680 ternary batteries, and the low-end will be dominated by CTP square lithium iron phosphate batteries.
BYD blade batteries, blade batteries on Han EV also use lamination process
Then the Ningde era will face the 4680 battery and BYD blade battery on both sides of the pinch, BYD itself is a battery to start, coupled with years has been specializing in lithium iron phosphate batteries, with the production capacity of The Fordy battery began to expand significantly, here you can refer to the article "Accept Weilai, Millet, Fordy's attack has just begun", it is bound to eat a part of the share of the Ningde era.
CATL CTP 3.0 Kirin Battery advertises that the system energy density of ternary lithium and lithium iron phosphate can reach 250 Wh/kg and 160 Wh/kg respectively, and can achieve the highest safety requirements for heat-free diffusion
However, in the past electric vehicle 100 people will be 2022, the Ningde era also gave a counterattack - CTP 3.0 version of the Kirin battery, whether it can maintain the current absolute leading position, specifically depends on the landing effect of CTP 3.0 and the speed of cost reduction and efficiency.
04
Which car companies and battery factories are following up on the layout of large cylindrical batteries?
At present, from the perspective of car companies, the main promoter is Tesla, 2022Q1 Tesla has begun trial production, and at the end of the year, it may be able to deliver a small number of 4680 Model Y to consumers. The real outbreak period is after 2023, when the Long-hopper Cybertruck and Heavy Truck Semi will gradually meet with everyone. BMW's 4695 battery gives a mass production time after 2024, which may become the main battery of BMW's future pure electric platform "Neue Klasse".
Lucid, a new car-making force in the United States, also uses a 2170 cylindrical battery
In addition, there are already many manufacturers of cylindrical batteries overseas, such as the new forces in the United States Lucid and Rivian are currently using 2170 batteries, and the future transition to 4680 batteries is also very natural.
LG Chem, the global share in the field of power batteries is second only to the Ningde era
On the battery manufacturers side, overseas battery manufacturers are mainly Tesla and Japan and South Korea, including Panasonic, LG Chem, Samsung SDI, Panasonic and LG Chem plan to mass production in 2023, Samsung SDI plans to mass production in 2024, and an Israeli company Storedot also plans to mass-produce 4680 batteries in 2024.
Domestic Ningde era is currently planning 12 GWh of 4680 battery production capacity, the pace of research and development is accelerating, is expected to start mass production in 2024, customers may be Tesla and BMW; BAK battery in March 2021 in Shenzhen CIBF exhibited large cylindrical products, is expected to be mass production in 2023; Ewell Lithium energy is expected to achieve mass production of 4680 batteries in 2024, planning production capacity of 20 GWh, while there is also a plan to build a factory in Hungary, Europe.
On the whole, compared with the upgrade from 18650 to 2170, the 4680 battery squeezed the toothpaste this time, basically determining the development direction of the cylindrical battery, and is also expected to lead the market share of the cylindrical battery to achieve rapid catch-up with the square battery. However, the 4680 battery still faces many process problems, such as the full pole ear battery laser solder joint is at least five times more than 2170, the accuracy requirements are very high, and the curved edge of the full pole ear coating has higher precision requirements for the equipment, and the future development of the 4680 battery focuses on when the yield rate of Tesla, Panasonic, LG Chem and other companies can stabilize at more than 90%.
Author: Wu Gangxing
Edit: Reinhardt
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