BYD CTB makes Musk unable to laugh anymore?

Bitauto Original An interview in which Tesla CEO Musk mocked BYD has appeared in my social media more than once over the years. Musk’s straightforward argument expressed his views on BYD at that time: “a company with no technology and a car price that was too high for the product.” The three times in front of the camera couldn't help laughing, and it was the final critical blow to BYD. The reason why this video has appeared more than once is because of BYD's success over the years. With the launch of BYD Seal on May 20, the CTB battery body integration technology behind it is more like preparing a 10-year counterattack for Tesla and Musk.

What is battery body integration?

The development of power batteries is a process of increasing energy density and reducing costs. It is divided into two paths: chemical materials and engineering physics. At present, it is still too early to make revolutionary progress and final mass production through chemical materials to improve energy density, charging time and battery life. Therefore, relying on engineering physics means to increase battery energy density and reduce costs has become the most practical way, and battery-body integration falls into this way.

Battery solutions based on the engineering physics approach can be roughly divided into three stages:

1.0 era: Engineers integrate cells into modules, and the modules are then integrated into battery packs for packaging. The biggest advantage of this method is that the module can independently manage cell safety and prevent thermal runaway. And manufacturers can flexibly arrange the battery layout through different vehicle model architectures. This era is also the era when the so-called "gas-to-electricity" models are most popular. But the disadvantage is that it is bulky, the module takes up too much chassis space, crowds out passenger space, and the battery density is low.

The 2.0 era: The intermediate module design is cancelled, and the cells are directly integrated into the battery pack (Cell to Pack, or CTP). This is currently the most mainstream battery integration solution. Compared with the 1.0 era, the elimination of modules has improved space utilization (the space utilization rate of BYD's blade battery pack can reach 60%), and the reduction of components has also reduced costs.

The 3.0 era: here comes the battery-body integration. The battery cells and the car body are further integrated, the battery pack is eliminated, and the battery cells are directly placed on the chassis for packaging (Cell to Body or Cell to Chasis, i.e. CTB or CTC). Compared with the 2.0 era, this solution is more integrated. The battery pack is eliminated, the space is further expanded to place battery cells to provide energy density, and the riding space and cost are further optimized. But the difficulty with this type of technology is how to ensure battery safety and stability after canceling the battery pack design. I will explain BYD’s solution to this problem later.

So the focus of battery-body integration is to cancel the module and battery pack. This is also the reason why I think the CTC solution released by Leappo earlier cannot be regarded as a true battery-body integration, because compared to CTP, Leappo’s solution eliminates the battery cover to optimize space, but it is still The design of the battery module is retained. Perhaps the greater significance of announcing its plan ahead of BYD is to grab the C01, which is known as "the world's first mass-produced sedan equipped with CTC technology", and build momentum for its subsequent listing on the Hong Kong Stock Exchange.

Characteristics of BYD CTB

Then BYD CTB solution can achieve true battery-body integration, relying on the strong stability of the blade battery itself. Without the protection of a battery pack, the slender blade batteries are arranged and combined to further increase their strength and act as chassis structural members. In addition, BYD added a cross member to the frame to enhance lateral strength.

In terms of vertical structure, BYD drew inspiration from the honeycomb structure and added a high-strength honeycomb aluminum plate above and below the battery core to form a stable structure similar to honeycomb aluminum. BYD demonstrated the pressure resistance of the CTB blade battery through an experiment in which a 50-ton truck crushed the blade battery. It can be seen from the picture that the battery has not been deformed as a whole and can be installed in the car immediately. While considering integrated design and battery safety, it also takes into account the convenience of certain later maintenance.

Compared with the zero-run CTC solution, the stability advantage of the blade battery allows BYD to rest assured that the battery can act as a structural component to bear force to a greater extent.

BYD Seal's body torsional stiffness is higher than that of Leappo C01 (BYD Seal: 40500N·m/deg, Leapmoor C01: 33897N·m/deg), which is also verified from the side.

Benefits of CTB to BYD Seal

The first benefit is space optimization. Seal is BYD's first model to use a front double wishbone and a rear five-link suspension. In addition, CTB also reduced the overall height of Seal's body by 10mm, helping Seal obtain a drag coefficient of 0.219Cd. The omission of the battery pack design also increases the chassis space utilization rate from 60% to 66%, and the energy density and cruising range will be further improved. The SEAL long-range version can reach 700km under CLTC standards.

The second is the improvement of body safety. The use of CTB increases the torsional stiffness of the vehicle by 70%. The torsional stiffness data of 40500N·m/deg can now be achieved on a B-class sedan priced at 212,800-289,800 yuan. It is conceivable that the Seal's handling will also be significantly improved during intense driving.

Tesla’s counterattack?

Tracing back to its roots, the battery-body integration technology was proposed by Musk at Tesla Battery Day in 2020. Tesla calls it Structural Battery. Moreover, neither Leapmoo C01 nor BYD Seal are the first models in the world to mass-produce this technology. Because this label has been snatched away by the Model Y produced at Tesla's Texas Gigafactory. In addition, these Model Y also use 4680 batteries. Therefore, 4680 battery + battery body integration is Tesla’s counterattack. And CATL started construction of a new factory near Tesla's Shanghai factory in February this year. The purpose is to mass-produce Tesla's battery body integration and 4680 battery solutions this year.

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