Leapmotor / BYD "preempts" Tesla, CTC / CTB will become standard for new car manufacturers

In recent years, with the joint efforts of the power battery industry chain, the energy density of batteries has been significantly improved, and long-range models have developed rapidly. However, the current long-range models mainly rely on battery stacking, which also brings about derivative problems such as body weight, and does not solve the market's anxiety about the range of electric vehicles.

To this end, continuing to improve the energy density of battery packs and lightweight vehicles has also become a necessary issue for the new energy vehicle industry chain. "In the case where it is difficult to greatly increase the energy density of the battery, the integrated technology of the battery and the body can be regarded as an effective solution, which can not only increase the energy density of the battery pack of a bicycle, but also reduce the weight of the car and improve the battery life of the car. Mileage, we predict that this technology will develop rapidly in the future." said Chen Lei, an analyst in the lithium battery industry.

With the support of CTC and CTB, integrated integration significantly reduces costs and increases efficiency

The changes of electrification to cars are becoming more and more obvious. It is not only a change in power mode, but also obvious changes in body structure, component composition, car manufacturing cost, car experience, etc., and these changes are still Constantly optimize. Among them, the power battery pack, as one of the core components of the new energy vehicle, accounts for 30%-40% of the weight of the whole vehicle. How to realize the "lightweight" of the battery has become an important research and development topic for various battery companies and OEMs.

In order to promote the "lightweight" of battery packs, CATL launched CTP (Cell to Pack) technology in March this year. By eliminating the assembly process of battery modules, the energy density of battery packs can be increased by 10%-15%. This technology can also effectively reduce the cost of the battery pack and significantly improve the production efficiency, but this is not enough for OEMs. The integration of the battery with the body and chassis has become one of the research directions.

Previously, Tesla proposed an integration solution for CTC (Cell to Chassis) cells and body chassis. According to the plan, Tesla's CTC technology directly installs the battery cell on the body, and with the integrated die-casting technology, it can reduce 370 parts and components. The cruising range is increased by 14%, and with the newly developed 4680 large cylindrical battery, the energy density of the integrated "battery pack" can be further improved.

The advantages of the integrated battery-body-chassis integration technology first proposed by Tesla are obvious, but it is not Tesla that is the first to launch related products, but the domestic Leapcar . In late April this year, Leapmotor officially announced the launch of the battery-chassis integration technology (CTC). According to reports, this technology can increase the battery layout space by 14.5%, reduce the cost of structural parts by 15%, and increase the comprehensive engineering by 10%. The torsional stiffness of the body can also be increased by 25%. This technology has been installed in its newly launched Leapmotor C01 model.

Then on May 20, BYD also released its own CTB (Cell to Body) battery body integration technology, which further integrates the battery cover and the body chassis into one, from the original battery pack "sandwich" structure, It has evolved into a "sandwich" structure of the entire vehicle. BYD said, "The power battery system is both an energy body and a structural part. This fusion simplifies the body structure and production process, and is a subversive change to the traditional body design."

This structural change enables the CTB blade battery pack to withstand the extreme rolling of a 50-ton heavy truck without damage, and the torsional stiffness of the body can easily exceed 40,000N m/°. Performance indicators such as power consumption per 100 kilometers have been significantly improved compared with traditional platforms. According to industry insiders, the application of battery-body integration technology has raised various indicators of new energy vehicles to a higher level.

Comparison of Leapmotor, BYD, and Tesla plans (public data collation)

As mentioned above, the ideas of the above three OEMs are to directly install the cells or battery packs on the body chassis, eliminating the traditional complex links of "battery cells-battery packs-battery packs-loading", so that the body chassis is "battery". package" lightweight integrated design.

According to public information, the underbody of the Leapmotor solution is the upper cover of the battery pack, with the battery pack in the middle, which is then packaged by a tray to realize the integration of the battery and the body. BYD also uses the design of the bottom plate of the body, that is, the upper cover of the battery pack, and then the blade battery is packaged and integrated by the bottom plate, and adhesives need to be added to the top and bottom of the battery. Tesla's plan cancels the Pack design, uses a highly viscous, flame-retardant colloid to fix the cell to the bottom plate, and uses a serpentine tube to cool the cell.

The difference is that the Leaprun solution is to first make the cells into a battery pack, and then integrate the battery pack into the chassis of the car. Since this solution has been processed safely in the module link, the safety measures required in the integration link of the vehicle are relatively low. It is much less "lighter" than the other two solutions. Although the names of Tesla and BYD's solutions are different, the ideas of the two are more similar, both integrating large cylindrical cells or blade cells into the chassis; among them, BYD's CTB solution retains the chassis beam; Tesla 's The CTC plan is to cancel the body chassis beam, and then add a beam on the battery cover. Industry insiders believe that Tesla's plan is more radical. 

"Lightweight" batteries are sought after, high maintenance costs or hidden worries

In fact, in addition to the above three early adopters, Canoo, an American electric vehicle start-up company, has also launched similar technology products, and traditional OEMs such as Ford, Volvo, and Volkswagen also plan to accelerate the electrification transformation through a new battery-body integration platform. Not only that, power battery companies also want to enter this field to get a share of the pie. It is understood that CATL plans to achieve an integrated CTC in 2025 and upgrade it to an intelligent version in 2030; LG also disclosed CTC-related patents in 2021.

In addition to Leapmotor C01 and BYD Seal, Tesla's CTC model (Model Y) will also be released soon, and with the acceleration of vehicle electrification, the "lightweight" loading plan of power battery packs will also be launched in more car companies. roll out. In this regard, Chen Lei analyzed that, "In the case where it is difficult to greatly increase the energy density of the battery, the integrated technology of the battery and the body is an effective solution, which can not only increase the energy density of the bicycle battery pack, but also reduce the car's energy density. The weight increases the cruising range of the car, and we predict that this technology will develop rapidly in the future."

When comparing CTC and CTB technologies, the author also noticed that the current models are all pure electric models that support high-voltage fast charging. For the pure electric version, the cruising range of the 82.590kWh (sea seal) and 90kWh (C01) battery capacity models is 700 kilometers and 717 kilometers respectively. In terms of energy supplementation, both of them support high-voltage charging platforms. The seal supports 800V high-voltage fast charging and can last for 300 kilometers in 15 minutes; C01 supports 400kW super fast charging, and will be compatible with 800V high-voltage platforms in the future, with a battery life of 200 kilometers in 5 minutes. Chen Lei believes that fast charging has become the standard energy replenishment method for long-range pure electric vehicles. Moreover, as the integration of battery and body gradually becomes a trend, high-voltage fast charging will also become standard, making the energy replenishment of new energy vehicles more closely related. It is as convenient as a fuel car, improving the user's car experience.

However, whether it is the CTC solution or the CTB technology, when it changes the physical structure of new energy vehicles, it does not always bring good development, and there are also some shortcomings , "Just like our mobile phones, when we used to support battery replacement, The battery can be removed by opening the back cover, but now it can only be removed with special tools to replace the battery. The car is more complicated. After the integrated integration technology is adopted, the battery is connected to the body as a whole, which is convenient for assembly, but not for maintenance. It’s convenient. If the car has an accident, the battery part needs to be repaired. It may not only be the battery pack that needs to be replaced, but also the chassis may be replaced together. This will greatly increase the maintenance cost for users.”

It is understood that high maintenance costs have become a common problem in integrated design. Recently, media reports said that the repair cost of a Tesla damaged in reversing was as high as 200,000 yuan, while the total price of the car was 280,000 yuan. The analysis said that the damage to the integrated die-casting parts resulted in high maintenance costs. main reason. However, Chen Lei believes, "Any new technology cannot have only good and no bad. When the OEM is doing the integrated design, it must have taken full safety consideration, such as BYD's honeycomb structure, if this component needs to be replaced , that means it has been a major accident."

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