【E is easy to understand】For the fuel vehicles that are common on the street, you may already be familiar with their driving principles. Use fuel as the driving source, store it in the fuel tank in the car, and then transport the fuel little by little to the engine through the pipeline to ignite and deflagrate, and then use the power after deflagration to push the piston in the cylinder to This drives the crankshaft to allow the vehicle to move.
Of course, maybe what I said above is very one-sided and not detailed. That is because mentioning fuel vehicles is just an introduction to the following, and this "subsequent" is the "main course" we are going to serve today - power. Battery technology.
Speaking of which, do you feel that fuel vehicles and power battery technology are very incompatible? In fact, if we look at the two from another angle, they are actually somewhat "related". For example:
fuel vehicle engine → pure electric vehicle drive motor
fuel vehicle fuel → pure electric vehicle electric energy
fuel vehicle fuel tank → pure electric vehicle power battery
and so on...
In this issue, E will understand, just Let’s discuss this “fuel tank” technology, which is the development of the latest power battery technology.
Generally speaking, in pure electric vehicles, the power battery pack is the only source of power for the car. The amount of electrical energy stored in the power battery pack determines the driving range of the electric vehicle . There are two ways to increase the power of a power battery pack: using high-capacity cells or adding more cells.
At present, the power battery packs of new energy vehicles are mainly ternary lithium batteries and lithium iron phosphate batteries . Among them, ternary lithium batteries have the advantages of high density and large capacity, and are the mainstream use solutions for many models; while phosphoric acid Lithium-iron batteries have the advantages of high safety and low cost. However, because the energy density is not as high as that of ternary lithium, they are only favored by some car companies.
So here comes the key point. A ternary lithium battery is a lithium battery that uses nickel cobalt as the cathode material and manganese salt or aluminum salt as the stable chemical structure. The main components are nickel cobalt manganese (NCM) and nickel cobalt aluminum. (NCA). In nickel-cobalt-manganese batteries, they are divided into NCM111, NCM523, and NCM811. The numbers represent the ratio of nickel-cobalt-manganese. The higher the nickel content, the higher the energy density of the battery cell and the greater the capacity. Therefore, many mid-to-high-end models that value long battery life use NCM811 batteries. At present, the international nickel price is soaring. Li Xiang even described the increase as "very outrageous". According to estimates by relevant investment banks, the rise in nickel prices will directly lead to an increase in the production cost of a pure electric vehicle by US$1,000, which is equivalent to more than 6,000 yuan.
No, in March this year, batches of domestic new energy car companies have successively issued price increase notices. Each model has experienced a different increase in price, ranging from thousands to more than 10,000. Therefore, it can be seen that if the battery core is changed only from the material, the higher the capacity, the higher the cost. Therefore, by expanding the "fuel tank" and changing the internal structure of the battery pack to accommodate more cells, the battery life can be improved without changing the battery material. So, how to change the battery pack structure to increase capacity?
Here we will mention a formula: battery pack energy density = cell energy density × group efficiency.
From this formula, we can see that in order to achieve high energy density at the battery pack level, in addition to improving the quality of the cells, it is also very important to improve the group efficiency. The internal structure of
's early battery packs consisted of three parts: battery cells, battery modules and power battery control systems. We have already talked about the battery cells before, so we won’t go into details here. The battery module gathers these individual cells together to eventually form "energy bodies" one after another.
Of course, in addition to these modules, the entire battery pack also includes battery management systems, thermal management systems, high and low voltage circuits and other components. Their distribution occupies part of the weight and internal space of the battery system, and its group efficiency is 60%~70%! In other words, if you buy a house, 60%-70% is only your usable area, and the rest is the shared area.Therefore, if the power loss caused by pipelines and other components is added, the energy density of a complete battery pack is lower than the energy density of a single battery cell.
According to a conclusion made by a domestic company, a battery cell with a single energy density exceeding 300Wh/kg will still have an energy density of around 160Wh/kg at the battery system level due to the limitation of the traditional battery pack grouping method. Therefore, how to improve the battery pack assembly rate has become one of the best ways to increase the energy density of power batteries. So, how to do it?
's very simple approach is to don't need it if you can, and "subtract" it from the battery. The first thing to do is to reduce or eliminate the number of battery modules.
Early electric vehicles were in the initial stage of technology. For the safety of the entire vehicle, especially to reduce the heat transfer phenomenon caused by thermal runaway caused by battery short circuit, the "cell-battery module-battery pack" was adopted. The packaging form is like the compartment design used in ships, which blocks the inflow of seawater through partitioned waterproof doors.
In addition, the module is also designed to better gather and manage the cells. For example, and Tesla use more than 7,000 battery cells. If they are directly assembled into the battery box, the assembly complexity will definitely be a big project, so the production efficiency will be very low. Therefore, it is very important to pre-integrate some battery cells. Therefore, we can see that the early Model S has more than ten modules, and with the wiring harness wrapped around, its size can be imagined.
With the continuous development of battery technology and the gradual increase in battery cell energy density, the number of battery modules has begun to be gradually reduced. Nowadays, only 4 large-size modules are used on Model 3, which greatly reduces redundant components. Not only that, most domestic car companies have also begun to use large-capacity square aluminum-shell batteries, providing opportunities for de-modularization. So, what are OEMs or battery companies doing now?
As we said before, without changing the cell material, only removing the battery module or reducing the size of the battery module to increase the number of cells to improve battery life. This technology is called CTP, which means cell to pack, which means to directly pack the cells. Integrated into the battery pack to eliminate "unnecessary" battery pack components, including cable module kits, etc. The representatives that use CTP technology are BYD and CATL .
BYD丨CTP technology with blade battery as the core
BYD, as an automobile manufacturing company with a background in battery manufacturing, naturally has a high level of battery research and development, and the most familiar one is the blade battery.
BYD's blade battery has changed from a rectangular structure to a thin strip shape, and the length can be adjusted according to different vehicle needs. It is then inserted into the battery pack like a blade and arranged together in an array, thus forming a A complete module-less CTP battery technology, and the most critical technology is the design of this blade battery.
It can be seen from the split that the battery pack is internally distributed from top to bottom with insulation cotton, thermal management modules, insulation materials, etc., and the outside is the battery case. There are also water-cooling heat sinks and strength mechanisms to support the battery inside.
First of all, the main battery material of BYD blade battery is lithium iron phosphate . Compared with our common ternary lithium, this material has more stable chemical properties and is a safer battery than ternary lithium. Material. However, the energy density of a lithium iron phosphate battery is usually between 90Wh/kg-120Wh/kg, while the energy density of a ternary lithium ion battery can reach about 200Wh/kg, so the energy density of lithium iron phosphate needs to be It is lower than the ternary lithium material, so if you want to improve the battery life, you have to "stack" it.
BYD Blade Battery elongates the battery cell to improve the battery itself. The longest length can be up to 2500mm, while the battery width and thickness are controlled at 118mm and 13.5mm, which means that in the width direction of the passenger car Only 1 battery needs to be placed at most.On the one hand, by adjusting the length specifications of the blade battery, the space in the width direction of the car body can be fully utilized, avoiding the waste of "leftover" space, and also eliminating a large number of component components.
Therefore, the advantage of such an arrangement is that it can increase the saturation of the battery cells and improve the energy density of the battery pack. Data shows that the space utilization rate of some traditional battery packs is about 40%, while the profit margin of blade battery pack space can reach 60%. Especially when the cathode material remains unchanged, the "volume-to-system energy density" of the blade battery is 50% higher than the "volume-to-system energy density" of the square-shell cell module battery pack. This is a good explanation for the fact that the average battery life of lithium iron phosphate electric vehicles can only reach more than 400 kilometers, but BYD electric vehicles equipped with blade batteries can exceed 600 kilometers.
Not only that, from the data we found that no matter how long the blade battery is, its thickness is very narrow. Why is this?
This is mainly because the blade battery is thin enough to leave more space for the battery's thermal management system layout. The early e-platform can only be paired with ternary lithium, which is more power-saving (low-power water pump) than traditional module lithium iron phosphate. Cold cycle, very easy to use in blade battery models. And because the lithium iron phosphate battery itself generates low heat, and the surface area of the blade battery is large enough, it will have sufficient heat dissipation capacity, thereby reducing the risk of thermal runaway.
In terms of strength, since the blade battery uses a hard metal casing, it can function as a supporting structure to a certain extent. Maybe you have heard of the chopstick theory, which is that one chopstick is easy to break, but a large handful of chopsticks is very difficult to break. The same is true for blade batteries. Through compact arrangement, the arrangement of the entire blade battery pack greatly enhances the horizontal or vertical structural strength of the battery pack.
In short, BYD's CTP battery technology is based on the unique shape design of the blade battery and the low heat generation characteristics of the cathode material. , making full use of every inch of space in the battery pack and "stacking" the batteries as much as possible, which can be said to be a "simple violent" technique. However, there are some issues worth pondering here:
First of all, the blade battery is designed to be so long and thick, so it is naturally impossible to use the traditional winding process for the battery core, so the blade battery uses a new lamination process to complete it. , which is to stack the battery materials layer by layer like a stack of quilts, and design the tabs at both ends of the battery core. The advantage of this is that it can effectively reduce the internal resistance of the battery, but the disadvantage is that this stacking method has great impact on the manufacturing process. High requirements, especially for the flatness of the tabs, may restrict the development of production capacity.
In addition, since the battery core is packaged in the blade battery, if the vehicle suffers a serious collision and the battery pack is deformed, then after the blade battery that is too long is deformed by external force, one battery cell is damaged, and the remaining batteries connected in series will be damaged. The core may also be affected, making it very difficult to ensure the integrity of the battery core, ultimately causing difficulties in repair.
CATL丨CTP technology that simplifies complexity
As the number one battery manufacturing company in China, as early as the 2019 Frankfurt International Auto Show in Germany, CATL launched a new CTP highly integrated power battery development platform, which is the first The first-generation CTP technology increased the battery pack volume utilization rate to 55%. In the same year, it jointly launched the world's first CTP battery pack with BAIC New Energy and installed it on BAIC EU5. After
, CATL launched the second-generation CTB battery technology, which integrated the original module cell voltage and current sampling and other parts, further reducing the number of module accessories, and integrating the cells directly into the battery box. According to data, since 2021, CATL's CTP battery packs have been introduced into Tesla Model 3, Model Y, Xpeng P7, NIO ES6 and other models on a large scale.
Of course, on how to obtain more "usable area", CATL has begun to dig deeper and integrate, and in the past few days officially released the third generation CTP battery technology, namely Kirin battery technology.In fact, if we look at the picture, we will find that its overall layout is similar to BYD's blade battery. The cells are stacked in segments into a strip-like layout. However, the cells use ternary lithium with higher energy density instead of ternary lithium. Blade batteries use lithium iron phosphate. Of course, according to the manufacturer's description, this technology will also launch a lithium iron phosphate version. I wonder which one of these two batteries is better?
Let’s get back to the subject. According to Kirin Battery’s data, the battery system’s integration level has reached a new high in the world, its volume utilization rate has exceeded 72%, and its energy density can reach 255Wh/kg, easily achieving a 1,000km battery life for the entire vehicle. And through the world's first large-area cooling technology for battery cells, Kirin batteries can support 5-minute hot start and 10-minute fast charging.
To sum it up in a simple sentence, Kirin Battery uses all the space inside the battery pack to reduce the "common area" as much as possible. First of all, on the previous CTP battery pack, when the top cover is placed upward, the battery pack needs to leave space for functional modules such as structural protection, high-voltage connection, and thermal runaway exhaust.
Kirin Battery arranges the cells inside the battery pack upside down (that is, the negative electrode faces up and the positive electrode faces down) and integrates structural protection, high-voltage connection, thermal runaway exhaust and other functional modules as much as possible The compact design allows the battery pack to hold 6% more space for cells. Don’t underestimate this 6% space. The cells it occupies are enough to increase the energy density of the battery pack to a new level.
In addition, I also think that another benefit of keeping the battery core upside down is to improve the overall safety of the battery pack after thermal runaway. Generally speaking, when the battery core experiences thermal runaway, due to the instantaneous decomposition of oxygen by the positive electrode, the oxidation reaction between oxygen and the solvent will produce a large amount of high-temperature gas or flame, which will be ejected from the pressure relief port on the top of the battery core. When the battery core is facing down, these high-temperature gases or flames will be discharged downward, reducing the risk of burns to people in the car.
In addition to this, Kirin Battery also adopts a "simplification from complexity" approach to the battery pack to integrate more structural parts.
First of all, Kirin Battery has canceled the horizontal and vertical beams, water-cooling plates and heat insulation pads used to support and strengthen the battery pack shell. Instead, it uses a multi-functional elastic interlayer that brings these three together. A structure called Micron is built in the interlayer. The bridge connection device can freely expand and contract with the thermal expansion and contraction of the battery core, thereby also improving the reliability of the battery core throughout its life cycle.
So, who is this multifunctional elastic sandwich? Let’s do this part of the analysis based on the patent pictures we collected.
's patent for this multifunctional elastic sandwich is called "Water-cooling plate assembly, water-cooling system, battery and its box and electrical device". It can be seen from the overall appearance that it is a long rounded rectangle with a central hollow structure. structure.
From the patent drawing, number 371 is the cooling channel on the inner layer of the mezzanine, and number 372 is the cooling channel on the outer layer of the mezzanine. They are mainly used to guide the coolant in series. Among them, 371 occupies the largest area, so that it can be more Extensive take away the operating temperature on the battery cells.
According to official statements, the interlayer water cooling function is placed between the cells, which increases the heat exchange area by 4 times. This large-area cooling technology of the battery core shortens the temperature control time of the battery core to half of the original time, allowing the Kirin battery to easily meet higher current and higher voltage fast charging. In addition, the Kirin battery also supports 5-minute fast hot start and It can be quickly charged to 80% in 10 minutes, which can be said to be a very high achievement in the industry.
and number 373 is a reinforced structure, of which 373a and 373b are reinforcement ribs in the cooling. This design is like the beams and columns built in our houses, which can further strengthen the structural strength of the coolant channel, and can also Prevent the cooling channel from deforming or even breaking under the action of external force.
The picture below is a patented diagram of the combination of the multifunctional elastic interlayer and the battery core. It can be seen from the picture that liquid cooling tubes are connected to both ends of the multifunctional interlayer, and this liquid cooling tube can cool all the components in the battery pack. The multi-functional sandwich panels are connected in series to establish an internal circulation channel and improve the structural strength between the multi-functional sandwich panels.
Another thing worth noting is that according to the promotional video, the two ends of this multifunctional elastic interlayer are designed with a structure similar to a buffer energy-absorbing box, which can absorb the expansion of the battery core due to the charging and discharging process. First of all, when the battery cell is in the working state of charging and discharging, lithium ions are embedded in the layered material, causing the thickness of the pole piece to increase. This expansion is reversible, while the other irreversible expansion mainly forms SEI during the formation process. The film is caused by the gas produced.
If the battery core expands excessively, its internal pressure will increase, and the performance and life of the battery core will decrease. And if the cell expansion is excessively restricted, such as wrapping it tightly, the cell separator will also be squeezed, which will accelerate the attenuation of the cell capacity. Therefore, most companies will reserve some space for the battery cells and the battery pack casing. This will result in a waste of space and volume, and will also increase the thickness of the battery cells and widen the gap between the positive and negative electrodes of the battery cells. distance. The elastic interlayer of the Kirin battery can absorb the size tolerance changes caused by the cell expansion, preventing the single cell from being squeezed, thereby increasing the battery's cycle life.
In addition, according to the official statement, this multifunctional elastic sandwich also has a "built-in micron bridge connection device", which may be a highly elastic polymer material used to fill the channels inside the sandwich. , improve the overall plasticity.
In fact, it can be seen that the main core of Kirin battery lies in the design of this multi-functional elastic interlayer. Its comprehensive and integrated functions cover the functions of cell cooling, battery pack lateral structural support and cell heat insulation, reducing the internal structure of the cell. The volume of the components is reduced, freeing up space to store more batteries, and achieving thermal stability and thermal safety of the full chemical system, thereby adapting to higher energy density material upgrades and effectively meeting the needs of 800V voltage platform models.
However, what I want to say here is that from the structure of this multi-functional elastic sandwich, its lateral support strength feels lower than the strength of traditional horizontal and longitudinal beams, but I personally think that it is a battery pack technology after all. The safety will naturally be placed on the body chassis. In addition, we will continue to dig into the issue of whether the Kirin battery cells are easy to replace.
Of course, from a macro perspective, CTP technology still retains the overall battery pack, so the weight has also increased accordingly, which is absolutely "intolerable" for battery life. So, wouldn’t it be great if the battery pack was removed to reduce this weight and improve battery life? Therefore, in order to further improve battery life and eliminate "unnecessary" battery pack components, some car companies have developed new CTC technology (Cell To Chassis), which is battery-chassis integration technology.
Overall, this technology can actually be regarded as an "extreme". It basically does not even need a battery pack. The battery is placed directly on the chassis, which means that the members in the car sit directly on the power battery. . Moreover, the structural strength of the battery system of CTC technology is completely guaranteed by the strength of the battery shell and the strength of the body, so this will have more stringent requirements for battery production. There are now two well-known CTC battery technology companies, namely Tesla and Leapmotor .
Tesla丨CTC technology based on 4680 cells
Earlier, Tesla showed some technical details of Model Y for the first time during a visit held at the Berlin factory in Germany, including 4680 Structure battery is CTC technology based on 4680 battery.
It can be seen from the actual picture of Tesla CTC on display that the 4680 batteries are staggered and laid out in the body chassis, with the positive electrode of the 4680 battery cells facing upwards. The series and parallel connection of the battery cells is completed at the positive terminal, and the battery cells are connected in series and parallel at the positive terminal. Serpentine tubes are installed between the cores to cool the sides of the cells.
So in other words, Tesla directly arranged the 4680 cylindrical battery cells on the chassis, and the front and rear of the battery compartment were directly connected to two large body castings. The cockpit floor was gone, replaced by a battery cover, and the seats were directly installed on the chassis. Cover the battery.
Of course, the key point of Tesla’s technology is also the battery itself, which is the 4680 battery.
Tesla announced on Battery Day in September 2020 that it had developed a new size 4680 poleless battery with a height of 80mm and a diameter of 46mm. Compared with traditional lithium batteries, this battery without tabs no longer has protruding tabs at both ends of the battery. This design can significantly reduce heat generation, solve the heat dissipation problem of high-energy-density batteries, and increase peak charge and discharge power.
In addition, the 4680 battery uses silicon carbon anode material. In terms of energy density, this material is higher than the common graphite anode material at this stage, which can be increased by more than 8%, and the energy density can be increased by more than 10%. , ultimately making the energy of the new battery 5 times that of the past, and the power being 6 times that of the past. At the same time, the cost is reduced by 14%, and the cruising range is increased by 16%. How does
achieve Wujier?
In fact, Tesla 4680's "no pole ears" is just an "exaggeration", it still has pole ears. It's just that it's all concentrated to one side. You should know that the current common battery cells are all in the "jelly roll design" style, which is a way to roll the cathode, anode and separator together and connect them to the positive and negative terminals of the battery container through the cathode and anode ears.
However, when the battery is undergoing a discharge cycle, the resistance will increase as the endurance distance increases, and this will also increase the manufacturing cost. The core of the poleless technology is to remove the pole parts and directly connect the positive and negative current collectors to the cover shell, thereby doubling the current conduction area and shortening the current conduction distance. At the same time, the internal resistance of the battery is greatly reduced, the heat generation is reduced, the battery life is extended, and the peak power of charge and discharge is increased.
Also, with the use of Tesla's body-integrated die-casting technology and CTC technology, the new car is expected to lose 10% of its weight, increase its battery life by 14%, and reduce the number of body parts by as many as 370, which can be said to be an improvement in battery life. A lot of effort. It is worth mentioning that the welding method of the 4680 battery cells does not use the previous aluminum wire welding, but uses square metal sheets to connect the cells. At the same time, the collection boards of the battery management system are directly connected together to reduce the wiring harness in the battery pack. use and reduce costs.
Regarding the protection of thermal runaway , Tesla’s 4680 battery cells are filled with resin materials on the top, bottom and between the cells to provide thermal protection and structural support. According to the patent, resin materials can usually be appropriately adjusted within the limits of chemical substances, fillers and process requirements, so technicians can adjust the heat resistance and flame retardancy, tensile modulus , elongation , yield strength , bonding shear strength , mixing viscosity, processing time and density, one or more considerations to configure the resin material.
In addition, in terms of liquid cooling, the serpentine tube arrangement in the battery pack of Tesla's CTC solution is parallel to the axle direction, which can reduce the length of the serpentine tube, thereby reducing flow resistance and increasing the uniformity of cooling. . It is also equipped with eight pressure relief valves on one side of the battery core, almost all over the side of the battery pack. The advantage of this is that once thermal runaway occurs, the pressure relief valve can be quickly opened to reduce the risk of battery fire.
It can be said that the CTC technology of Tesla's 4680 battery allows Tesla, which is good at "subtraction", to continue to be a leading company in leading the development of the industry. However, as a person in the circle, we can also see from it that if this battery is really applied to the market There will still be some doubts.First of all, although the integrated battery installation in the car can fully expand the battery capacity, it is obviously very difficult to maintain a single battery cell. After all, the battery cells are "glued" together.
In addition, the 4680 battery uses a high-nickel solution, so the capacity has been improved, but the safety behind this still needs the test of time. Although the electrodeless mode can reduce the battery heat, the thermal runaway of the battery will occur after a collision. Can it be effectively controlled? It still needs to be verified by actual vehicles.
Leapmotor 丨 "CTC" technology based on large modules
As a new car-making force with the purpose of being a "technology house", Leapmotor officially launched its own CTC battery technology this year, which is also the first domestic The first company to mass-produce CTC models.
According to the official description, Leapao Intelligent Power CTC technology uses the body structure as the external structure of the battery pack, cancels part of the structural design of the battery pack, and reduces redundant structural design. The vertical space of the vehicle is increased by 10mm, and the battery layout space is increased by 14.5%. It makes the interior space layout more flexible and practical.
Specifically, we can see from the physical exploded view that Leappo’s CTC technology seems to be very simple. Compared with Tesla’s state of “sitting” on the battery, Leapao has designed a chassis for the car body. The large recessed pit is used as the battery compartment, and the battery module is fixed and suspended in the battery compartment from bottom to top by bolting, gluing, etc., and a protective cover is added to form a sealed space.
This feels like the four-wheel drive we used to play when we were kids.
Speaking of which, I wonder if you have noticed the difference between Leapao CTC and Leapao CTC. That is, compared to Tesla’s design that is full of battery cells, Leapao CTC adopts a battery module design! So instead of saying it is CTC, it is more appropriate to call it MCT, which means Module to chassis.
Judging from the patent drawings, Leopao’s CTC battery pack seems to be slightly lower than Tesla’s solution in terms of volume and integration. So does this mean that Leap CTC is not as good as Tesla?
It’s really not...
First of all, the biggest advantage of Leapmoon’s CTC technology is that it can easily maintain the battery cells. It adopts an upper cover sealed structure cabin + lower cover + rubber strip scheme to achieve full sealing of the battery module. It not only has good waterproof performance, but also achieves simple and effective maintenance. It can be said that Bits Pulling is much better.
Also, in terms of the structural strength of the battery system, Leapmoon CTC designed a reinforced plate design including cross beams and longitudinal beams, and designed a triangular force transmission guide block on the side of the battery compartment, which can be used when the vehicle is subject to greater force. In the event of a large side impact, the lateral force is converted into longitudinal force and transmitted to the front and rear body longitudinal beams to prevent the support beams between the modules from deforming and thus damaging the battery core.
According to official data, Zero Run CTC technology can increase the torsional stiffness of the vehicle by 25%, and the lightweight coefficient reaches 2.4, an increase of 20%. The higher the torsional stiffness of the car body, the stronger the ability to resist resonance , which means that the vehicle can have better driving control performance, better chassis response efficiency, and can also help NVH performance.
In addition, in order to prevent spontaneous combustion after a collision, Leappo has added a protective gas bag directly outside the CTC, which is filled with compressed nitrogen and connected to the battery compartment through pipelines. Once it encounters a collision, the protective gas will be pressed into the battery compartment and the air will be exhausted, creating an oxygen-deficient environment, thereby inhibiting spontaneous combustion.
I have to say that this solution is really wonderful...
Overall, although there is still room for improvement in Leapmoon's CTC battery technology in terms of compactness and integration, the overall design concept does Battery safety is a focus. After all, the batteries are not self-produced, and if they are installed in a large area, it is obviously not safe enough in terms of safety, so using a conservative method such as modules is also a helpless move for Zero Run.
BYD丨A combination of safety and capacity
For the former, we mentioned that BYD's blade battery is based on CTP technology, which is used to increase battery capacity and increase battery life.This CTP technology is based on the concept of battery packs, so the number of batteries has not reached saturation under its constraints. Although the CTC technology of Tesla and Leapao can do this very well, what should BYD do?
Not long ago, BYD officially released a new battery integration technology, and this technology is not the CTC we are talking about, but a new concept called CTB, which is Cell to Body battery body integration.
As the name suggests, CTB technology integrates all battery cells into the vehicle body. Its battery upper cover replaces part of the interior floor of the vehicle, and forms a flat and sealed complete body with the front and rear crossmembers to isolate the passenger compartment. From this point of view, BYD has integrated the battery system with the car body as a whole, and the sealing and waterproof requirements of the battery itself can be met. The sealing of the battery and the member cabin is also relatively simple, and the risks are controllable.
is designed in this way to protect the battery through the overall structural conditions of the car body. It can be said to be safer than other battery integration technologies. According to official data, the floor and upper cover are integrated to free up space and increase step utilization by 66%. Structural parts participate in the force transmission of the entire vehicle, and the torque stiffness is twice that of a fuel vehicle, breaking through 40,000Nm/deg torsional stiffness, which is basically on par with the Rolls-Royce Phantom . Among them, the safety of the front-impact structure has been improved by 50%, and the safety of the side-impact structure has been improved by 45%. According to the official video, the BYD CTB battery was crushed by a 50-ton truck and remained intact. The battery can be put back on the vehicle and can continue driving.
However, it is worth mentioning that the space saved by BYD's CTB solution is not used to load more batteries. Instead, this space is reserved for the passenger compartment, increasing the vertical space in the car by 10mm. Don't underestimate this short 10mm, the comfort it brings to drivers and passengers is immeasurable.
In addition, in terms of structural safety, BYD's CTB technology adheres the blade battery to the tray and upper cover to form a "sandwich" structure similar to the honeycomb aluminum plate. In this way, the blade battery, which already has high safety, plus CTB technology The stronger sandwich structure formed greatly improves the structural strength of the entire battery pack.
Of course, CTB technology brings more than just battery capacity and safety. Since this technology allows the battery pack to be well embedded in the car body, there is no need to raise the chassis to protect the battery like traditional electric vehicles, and the body is placed as close as possible. Lie low to effectively reduce wind resistance. It also allows the vehicle to have a front and rear axle load ratio of 50:50. According to data released at BYD's press conference, the Seal model equipped with CTB technology passed the Elk test at a speed of 83.5km/h and the line transfer test at a speed of 133km. /h, the maximum lateral stable acceleration of steady-state rotation is 1.05g, which means that Seal has reached the sports car level.
Of course, although CTB has some advantages, it still cannot get rid of the disadvantages of rising maintenance costs caused by battery integration. However, we still need time to wait whether this problem can be effectively solved in the future.
is written at the end:
The development of electric vehicles is obvious to all of us. Although the research and development of high-energy-density battery materials is somewhat slow now, based on the blessing of battery integration technology, judging from the current development, it is definitely a good one. solution. As OEMs and battery companies are now deploying new battery technologies, this is definitely a good thing for us consumers. After that, EV Vision will spread more knowledge about new energy vehicles, so stay tuned.
