"Celebrate for the 1 millionth 4680 battery produced in January!" A few days ago, Tesla announced the news on the overseas social platform Twitter, which means that its long-laid out 4680 battery technology has taken a big step forward on the road to mass production.
Tesla's 1 millionth 4680 battery rolled off the production line; image source: Tesla Twitter screenshot
It is understood that Tesla's 4680 battery was first disclosed on the "Battery Day" held in late September 2020, when Tesla CEO Elon Musk regarded it as a "huge breakthrough" in battery technology.
As the name suggests, the 4680 battery is named after the size and is a cylindrical battery with a diameter of 46mm and a height of 80mm. So, compared with the existing cylindrical battery, what are the breakthrough points of the 4680 battery? In addition to Tesla, do related power battery companies have a layout? How long will this new battery technology be away from mass production?
Three innovative technologies, Tesla 4680 battery performance, better cost
In the choice of power battery packaging form of application, most domestic car companies mainly use square batteries, foreign countries are mainly soft pack batteries, and Tesla is one of the few large-scale use of cylindrical power batteries, from the earliest Model S used in the 1865 battery, to the current Model 3 and Model Y used on the 2170 battery, and then to the mass production of 4680 battery, are cylindrical.
From Tesla's battery naming, it can be seen that compared with the previous two generations of batteries, the new generation of 4680 batteries has increased a lot in diameter and height. Not only that, compared with the 2170 battery, the capacity of the 4680 battery can be increased by 5 times, the mileage of the vehicle under the same battery pack is increased by 16%, and the cost per kilowatt is reduced by 14%.
Tesla 4680 battery; Image source: Tesla
That is to say, the 4680 large cylindrical battery can greatly reduce the number of battery cells in a single battery pack. According to relevant data calculations, the previous generation of 1860 cylindrical batteries need 7200 + cells, the second generation of 2170 cylindrical batteries need about 4400 + cells, and today's 4680 large cylindrical batteries only need 950-1000 cells.
In the industry's view, Tesla's 4680 battery has made a huge breakthrough in product performance, which is inseparable from its innovation in cell structure and battery materials.
It is understood that in terms of cell structure, Tesla 4680 battery uses electrodeless ear (that is, omnipolar ear) technology, the traditional battery has two polar ears, respectively, connecting the positive and negative electrodes, and the electrodeless ear is directly cut from the positive / negative pole, shortening the polar ear spacing while also increasing the polar ear area. It is also based on this technology that the larger 4680 battery effectively solves the heat dissipation problem of high-energy density batteries.
Minsheng Securities pointed out that the 4680 battery using the new electrodeless ear technology can achieve cost reduction and efficiency, the electrodeless ear technology on the one hand increases the current conduction area, shortens the current conduction distance, greatly reduces the internal resistance of the battery; the internal resistance can reduce the current offset phenomenon, prolong the battery life; the resistance reduction can also reduce the heat generation, the electrode conductive coating and the effective contact area of the battery end cover can reach 100%, which can improve the heat dissipation capacity.
In terms of battery materials, the 4680 uses a silicon-carbon anode material. This is a material with a theoretical higher energy density than the traditional graphite anode, and the mass energy density of lithium batteries using silicon anode material can be increased by more than 8%, and the physical energy density can be increased by more than 10%. At the same time, because the voltage of the graphite anode is very close to the deposition potential of lithium, the silicon-based anode material has better safety in comparison. And silicon materials from a wide range of sources, low cost, is an environmentally friendly raw materials.
In addition, in the battery production process, the dry electrode technology used in Tesla's 4680 battery has set a new standard for power batteries. It is understood that traditional batteries need to be placed in toxic and expensive solutions such as NMP first, and then dried and pressed into a thin film. Dry electrode technology, on the other hand, eliminates the need for solution placement and drying, by mixing active positive and negative particles with polytetrafluoroethylene (PTFE) to fibroinate it, and then directly crushing the powder into a thin film and pressing on the raw material of aluminum or copper. The process is relatively simple and produces faster.
It is worth mentioning that the dry electrode technology not only saves the solvent cost and laminator cost brought by the traditional method, but also solves the problem of capacity loss caused by lithium and carbon in the solvent if it cannot be fused, thereby increasing the battery energy density by about 5%.
Many battery manufacturers followed suit, and the 4680 battery is expected to become an important technical route
In the development process of automobile electrification, the mileage and cost have always been important factors restricting the rapid realization of the full penetration of pure electric vehicles in the market. And since 2021, the power battery raw materials have suffered multiple price increases, making the demand for car companies to increase efficiency and reduce costs more and more intensely, and the 4680 large cylindrical battery, which has more advantages in performance, cost and safety, has become one of the important options for car companies.
It is reported that in addition to Tesla's own launch of 4680 batteries, including Porsche, BMW, JAC, Dongfeng and other car companies are also interested or have jointly promoted the development of large cylindrical batteries with battery companies, hoping to be applied to related models in the future. According to relevant industry insiders, Porsche and BMW are working with some battery suppliers to develop large cylindrical batteries, but the specifications and models have not yet been determined. Qin Liwei, deputy director of the battery system department of Jianghuai Automobile New Energy Automobile Research Institute, once revealed that at present, Jianghuai Automobile is planning a new platform based on the 46 series, and will develop 46800/46105 series batteries in the future and realize the whole package of CTP.
In this context, power battery companies such as Panasonic, Ningde Times, LG New Energy, and Ewell Lithium Energy have begun to actively lay out 4680 batteries.
A few days ago, Panasonic said that it is expected to start trial production of 4680 electric vehicle batteries in April this year, after which the company also intends to conduct further trial production in Wakayama Prefecture near Panasonic Osaka headquarters, but the time and location of official large-scale mass production have not yet been determined. At the same time, Hirokazu Umeda, chief financial officer of Panasonic, said: "When we are really able to deliver the 4680, we plan to give priority to Tesla. ”
The relevant person in charge of Ewell Lithium Energy recently said that the company's 4680 battery plant is under construction, and it is inconvenient for the partner to disclose. Ewell Lithium Energy has publicly stated that the company has completed the strategic layout of large cylindrical batteries, including two major models of 4680 and 4695, and is expected to release 20GWh in production capacity in 2023 and 40GWh in 2024.
IN MARCH 2021, BAK Battery showed off its self-developed 4680 battery cell. Lin Jian, chief scientist of BAK, said that BAK has cooperated with customers to develop the application of full-pole ear large cylindrical batteries, and is expected to start mass production in 2023. According to BAK Battery, the company is currently conducting joint development of large cylindrical batteries with internationally renowned car companies.
Soochow Securities said that there are huge advantages in energy density and production costs of large cylindrical batteries, and it is expected to become an important technical route in the future.
Improving yield rates is a top priority, with large-scale loading or in 2023
However, although the 4680 large cylindrical battery is good, but this new technology from the laboratory to the final large-scale mass production and loading, there are many problems to be overcome in the middle, the first is the yield rate problem.
Generally speaking, the yield rate benchmark for large-scale applications of power batteries is 90%, and if the yield rate is below 80%, there is no economy for large-scale mass production. From Tesla's point of view, since the launch of the 4680 battery in September 2020, it has begun trial production at the Fremont factory in California, USA. Through the efforts of the past year, the yield rate of Tesla's 4680 battery has increased from the initial 20% to 80%.
Some analysts pointed out that the reason why the yield of 4680 batteries is difficult to improve is still related to its overall structure. Its overall structure is: a layer of diaphragm, there is a layer of copper foil and aluminum foil at both ends to do the negative and positive poles, but the film is prone to positive and negative micro-short circuits during the winding process, when the self-discharge current is large to a certain extent, it will produce defective products; from the perspective of the internal structure of the battery, the fish scale coating technology used will also affect the yield rate when the coating is uneven; in addition, the connection between the omnipolar ear and the collector plate or shell needs to use surface welding technology, compared to the traditional spot welding of the two pole ears, the welding process and the amount of welding are more, Laser strength and focal length are not easy to control, easy to weld through the combustion into the battery cell or no welding, resulting in product unqualified.
A good news is that in the latest product inspection on January 22, 2022, the yield rate of 4680 batteries in 14 pilot production lines of Tesla's Fremont plant finally reached 92%, which also boosted the successful mass production of Tesla's 1 millionth 4680 battery off the production line. However, compared with the 2170 battery cell has already reached 99% of the industry yield status quo, the 4680 battery still has a lot of room for improvement. The industry generally believes that in the short term, the 4680 yield rate of about 95% will be a good number.
It is not difficult to understand that in the mass production timeline of 4680 and other models of large cylindrical batteries announced by the above enterprises, most companies will set the time for mass production of large cylindrical batteries in 2023.
This time, Tesla's 1 millionth 4680 battery mass production off the line, the industry should be a good start, the future with more battery manufacturers have entered the game, the yield rate of 4680 batteries is expected to continue to improve. CITIC Securities Research Report believes that tesla 4680 batteries have achieved mass production, which is expected to lead industrial change. At present, mainstream battery factories have followed up, and it is expected to usher in an outbreak in 2023. At that time, what kind of impact and transformation will this new battery technology bring to the existing battery market is worth looking forward to.