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Nowadays, due to the shortage of many automotive raw materials such as automotive-grade chips and wiring harnesses, the R&D progress and production progress of global auto companies have been affected to varying degrees. As a leader in the field of electric vehicles and a leader in the battery industry, BYD's strength is beyond doubt, and blade batteries are extremely competitive.
However, BYD still launched CTB technology. What are the advantages of CTB technology compared to the CTC technology we already know before? This starts with the current mainstream development trend of top 10 power battery companies in the world.
1. Development trend of power battery
From oil to electricity, the change in the power mode brings about a power increase. The biggest advantage of adding the form of "cell-module-battery pack" (commonly known as small modules) is that the cells are differentiated according to the form of modules for better management and relatively simple later maintenance.
However, in order to connect each other in series, it is inevitable to use a large number of cables and structural parts for connection, and there will be many redundant structures here, which not only reduces the utilization rate of the battery pack, but also makes the entire power battery very bulky. Similarly, there are inevitably some problems with the oil-reformed electric vehicle in the form of the above-mentioned "small module" battery pack.
In order to solve the above problems, the industry began to propose the concept of "CTP", that is, omit or reduce the number of modules, and arrange the cells directly in the battery pack. For example, BYD's blade battery is one of the examples. It directly adopts the design of no module, which greatly reduces the internal cables and structural parts, and effectively improves the volumetric energy density of the battery pack.
We all know that batteries are the main carrier of battery energy density. In theory, as long as the number is sufficient, the battery life of the vehicle can be effectively improved, but this involves many problems. At this stage, the power battery has filled the chassis space of the vehicle. If you want to continue to pile up blindly, there are only two choices-fill the trunk with batteries, or pull a box of lithium RV battery all over the street like a RV.
Obviously, neither of them is desirable, so the problem goes back to the beginning - how to further compress the battery volume and increase the density while ensuring a safe and stable increase in energy density. At this point, different technologies began to emerge in the industry. One is the CTC technology headed by Tesla and Leap, and the other is the CTB technology headed by BYD. The two technical routes seem to be the same, but they are actually different in structure and specific performance.
2. CTP vs CTC vs CTB, which one is better
CTP is a technology aimed at streamlining battery packs, but redundant design is required for installing the battery packs on the chassis. The CTC (Cell To Chassis) technology is that the battery is directly integrated on the chassis.
The main difference between CTC and the traditional battery installation method is that the upper cover of the battery pack or the floor of the cockpit is canceled, thereby further simplifying the body cables and structural parts. Different manufacturers have slightly different handling methods. For example, the CTC solution of Zero Motor is to cancel the upper cover of the battery pack, while Tesla's CTC solution is to cancel the cockpit floor.
Tesla's CTC solution, also known as structural battery, uses 4680 batteries and integrates the cabin beams and interior seats on the battery pack. That is to say, for the same CTC, Tesla's integration level is still higher than that of Zero Run, but this way there is almost no possibility of battery repair or replacement.
BYD's CTB (Cell To Body) is actually a bit similar to CTC technology, which installs the battery cells directly in the chassis. However, the difference is that CTC still treats the battery pack as a separate object to be protected, while BYD's CTB uses the high safety and high structural strength of the blade battery to integrate it into the overall design of the car body. The cells of the blade battery and the entire battery pack form a structure similar to honeycomb aluminum, which itself can function as a body structure.
So we see that CTP is just a battery pack technology, while CTC and CTB are a type of vehicle technology. Although in terms of integration, CTB is slightly inferior to Tesla's CTC solution, which means that BYD's manufacturing cost will be slightly higher than Tesla. However, in terms of structural safety and maintainability, BYD's CTB is still better. Obviously, this solution is more beneficial to users.
CTP vs CTC vs CTB technology comparison
|
Technology logic |
Pros |
Cons |
|
|
CTP |
Cell-battery pack (large module) |
Improve the volumetric energy density and mass energy density of the battery pack to reduce costs |
Higher requirements on the consistency of the battery cell, and it is difficult to repair and replace the battery cell |
|
CTC |
Cell-Chassis |
Increase the Z-axis space in the car, improve battery life and reduce costs |
There is still a lot of room for improvement in the level of integration, and it is difficult to repair and replace batteries |
|
CTB |
Cell-body |
Increase the Z-axis space in the car, improve battery life, reduce costs, improve body rigidity, and improve safety and handling |
There is still room for improvement in integration |
3. BYD CTB battery technology
Taking electric vehicles as an example, the most direct way to increase battery life is to increase battery capacity without changing the car battery voltage. However, the increase in battery capacity is accompanied by an increase in battery weight, which in turn leads to increased power consumption. Therefore, the higher the battery capacity, the smaller the gain in battery life.
At the same time, the larger the battery capacity, the higher the theoretical safety hazard. This has also become a difficult problem in the development of current electric vehicle technology. As a leading company in electric vehicles, the CTB technology released by BYD provides a standard solution.
The so-called CTB technology refers to the integration of battery and body. To put it bluntly, it is to integrate the battery pack with the chassis, so that the battery pack directly becomes a part of the body structure. The power battery is not only an energy body, but also a structural body. So, what are the advantages of CTB technology?
First of all, by canceling the design of the module and the upper case of the battery pack, more batteries can be loaded in a limited space, thereby increasing the battery capacity and increasing the cruising range.
Secondly, CTB technology can enhance the overall strength of the vehicle while reducing the weight of the vehicle's battery components.
In addition, CTB technology adheres the blade battery to the tray and the upper cover to form a "sandwich" structure similar to honeycomb aluminum plates. In this way, the already high-safety blade battery, coupled with the stronger sandwich structure formed by CTB technology, greatly improves the structural strength of the entire battery pack.
Finally, the most intuitive impact of CTB technology on the occupants in the car is that after the power battery pack is replaced by the body of the upper case, the longitudinal space in the car will be significantly improved, which can bring better ride experience to the passengers in the car. Moreover, after simplifying the body structure, the vibration of the body will naturally be reduced.
In addition to these intuitive performance experience levels, a hidden advantage of CTB technology is that because the structure of the power battery pack is not as complicated as the previous traditional battery pack, the use of parts is reduced. It can make the production efficiency higher, and compared to the model, the cost-effective advantage will be more obvious.
Compared with the CTP technology that directly omits modules and the CTC technology battery pack is still a separate entity that needs to be protected, BYD CTB technology obviously has more advantages in terms of overall structure. In other words, BYD CTB technology can be seen as an evolution based on CTP technology. Compared with CTC technology, although the battery cells are also directly installed in the chassis, BYD can take advantage of the high safety and high structural strength of the blade battery to make the overall body strength and safety higher.
4. Conclusion
To sum up, Tesla's CTC technology solution is relatively radical and highly integrated, but relatively poor in flexibility and maintainability. The zero-run CTC is not as lightweight as Tesla's extreme, and the risk of sealing the battery compartment is high. BYD's CTB solution is just right in terms of light weight and integration, and has high safety, which is more in line with future development trends.
Battery-body integration will take a different path from battery replacement. It remains to be seen whether the current battery density and performance can support the vigorous development of this technology. In short, pointing out and acknowledging these risks does not mean denying that battery-body integration technology is the general trend. The birth and development of new technologies requires some experience, and there must be something to be willing and rewarding. Everything has two sides, as long as any technology achieves a balance, it will be targeted.
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