Tesla blew the bull for 4 years, and was finally hit the pause button by himself. The 4680 battery, which Musk said increased the energy density of the monomer by 5 times and the power output increased by 6 times, failed to materialize in the end. Even in terms of loading effect, it is not as good as the current 2170 battery. After abandoning its own production of 4680 batteries, Tesla pinned its hopes on third-party supply. But can the problems encountered by Tesla be avoided by leaving them to suppliers? In the context of the huge demand for the overseas Cybertruck and the next-generation Model Y, what will Tesla do to survive the current window period?
The difficulty of monomer is in the process, and there is no advantage in teaming
First of all, it needs to be made clear that large cylindrical batteries, or 46 series large cylindrical batteries, will definitely be made. Behind this is actually a dispute over the technical route of lamination, winding and soft packing. As long as the technical advantages of winding are still there, large cylindrical batteries still have market value. However, the process problem of making the single battery bigger has always existed objectively, and it has affected the loading effect of Tesla's 4680 battery.
To sum up, it is nothing more than the same three things, winding difficulty, tab welding, and dry electrode. The design of the full tab makes the wound battery film need to be made into a serrated shape. In this way, the surface undulation of the tab will inevitably be uneven, affecting consistency. It is even easy to produce chips, resulting in poor yield. At the same time, the tab has changed from traditional electric welding to all-tab surface welding. The workload increases, and the process becomes more complex. Finally, dry electrodes, especially the highly active positive electrodes, are difficult to diffuse uniformly, and the yield rate is also reduced.
In fact, Tesla has long been compromising, and there are cobalt-free cathodes and silicon anodes in the original PPT. If it is said that in the face of the current positive electrode density, the graphite negative electrode is still more than enough. So cobalt-free cathode is the direction of struggle of many car companies, including Tesla. After all, this can further increase the capacity density of the battery and reduce costs. Of course, the 4680 battery that is mass-produced and installed is still a high-nickel ternary lithium battery. Therefore, the pressure of thermal management and structural stability still exists, not to mention cobalt-free batteries in this case. Tesla models with 4680 batteries have a high charging speed and then a low curve, which can also be attributed to this to a large extent.
In short, Tesla could not realize the talent of the 4680 battery in the process of the all-tab and the positive part. Expecting these things to be done by suppliers is also Tesla's regular thinking. It is reported that since the second half of last year, Tesla has purchased high-nickel cathode coils through Chinese suppliers and then assembled them in American factories. Combined with the cost pressure mentioned by Tesla when it suspended its own production of 4680 batteries, the authenticity of this news is still improving. As an important proportion of the cost in battery manufacturing, since cathode materials need to rely on imports from suppliers, the cost is understandable.
The problem of Tesla's 4680 battery installation is not only on the single cell, but also the embarrassment after the package. For example, in the early Tesla demonstration, the 4680 battery was a horizontal package. In the later period, it was changed to longitudinal packing. From horizontal to longitudinal, the contact area between the cooling pipe and the battery will become uneven. More importantly, the number of cells that can be accommodated in the longitudinal arrangement is not as good as that in the horizontal direction. The most direct effect is that it is difficult to increase the total capacity of the battery after the pack. The pressure of thermal management is high, and the total capacity of the battery cannot be increased, so why change it? The answer lies in security.
The longitudinally arranged batteries can leave more space for safety design on the longitudinal beams on both sides of the vehicle. At the same time, the same longitudinal cooling pipes will be better protected by the body structure. Assuming a horizontal layout, even if the battery cell can withstand the impact, the stability of the cooling pipe after the collision will be questioned. In addition, the cooling system is also a temperature control system. Extending from the front of the vehicle reduces the use of wiring harnesses and reduces energy loss. Finally, the weight of the battery, which makes it possible to arrange it farther away from the vehicle's central axis, increases the inertia offset on both sides. The longitudinal arrangement, which is arranged along the central axis, is theoretically more helpful for the handling of the vehicle. In other words, due to the constraints of the process, and for the sake of overall safety compromise, Tesla finally had to choose to abandon the plan to produce its own 4680 batteries.
It is easiest to use Kirin batteries, and choose BYD as a compromise?
The self-production of 4680 is tentatively determined, and the supplier's production capacity cannot support the demand for a while, and the 4680 battery itself still needs to be improved. So what about Tesla's current product iteration? Starting from the patent, Tesla can be said to be a full warehouse of large cylindrical batteries. There is not the slightest information to be found to invest in prismatic batteries. But because we don't have the relevant technology, it doesn't mean that Tesla doesn't have products that use prismatic batteries. The most typical is the Model Y and other models equipped with lithium iron phosphate batteries, and the supplier is CATL.
Since CATL has long-term cooperation experience with Tesla, it is indeed the easiest choice on the books to use Kirin batteries to meet Tesla's product replacement needs before the final volume of 4680. In fact, as early as after the release of the Kirin battery, there was a voice that Tesla would use the Kirin battery. When faced with questions in this regard, the reaction of CATL at that time was also ambiguous. It only means that this is a commercial secret and cannot be disclosed to the public. Of course, to this day, including after the Model 3 replacement, Kirin batteries are not used. However, as the progress of the 4680 battery has slowed down again, the Kirin battery, which has withstood the test of the high-end market, has become one of the few options that Tesla can use directly.
After all, the potential of the 2170 battery has been squeezed to the limit by Tesla. The performance of the Kirin battery is undoubtedly closer to the 4680 battery on the PPT 4 years ago. Ternary high nickel can reach an energy density of about 250Wh/kg, and even lithium iron phosphate can reach a level of about 160Wh/kg. The target depicted by the 4680 battery four years ago was 300Wh/kg. Although the Kirin battery is not yet reached, the 4680 battery is further away from this goal. The latter is still 13% away from the Kirin battery. More intuitively, whoever uses the Kirin battery at the moment is likely to achieve a range of more than 1000km.
Moreover, the module-free technology solution of Kirin battery is not suitable for the integrated die-casting and battery-chassis integration technology pursued by Tesla. In fact, the 4680 battery, which is used to restrain the displacement of the battery and provide safe redundancy through glue, has not considered the possibility of later maintenance from the beginning. It can only be said that the Tesla 4680 battery, which is a winding process and takes the large cylindrical route, intends to fundamentally solve the thermal management problem, and then discuss the battery capacity and performance after the package. The goal of Kirin battery is very clear, that is, to increase the overall capacity and performance. As for the ensuing problems, including heat dissipation, it is all left to the battery case itself.
Finally, there is a brain hole, which is the use of BYD's technical solution. Use the blade battery directly, there is no reason. Even if it is potential, long-laminated cells are currently becoming shorter and thicker to reduce internal resistance and improve performance. However, Tesla also has no precedent for applying this technology, and related patent support. However, 2 years ago, BYD released patent information for a hexagonal prismatic battery. Macroscopically, this can also be regarded as a "big cylindrical" battery, except that it is not round, but hexagonal.
Judging from the patent information, this battery can circumvent the two difficulties encountered by Tesla on the 4680 battery. First of all, it is not a pole-less battery, which is the so-called all-tab battery. Instead, the positive and negative electrodes are placed on one side, which is conducive to enhancing the heat dissipation effect on one side. Secondly, the gap between the single cells is fully utilized, which can improve the capacity density of the battery after packing. In fact, Tesla's current 4680 battery has a honeycomb-like plastic base for limiting. From this point of view, BYD's hexagonal plan battery can also be adapted from the physical structure. However, the non-electrodeless route can only be regarded as a compromise for Tesla. As for whether it can meet the high-nickel ternary lithium scheme, it is another matter.