Since the goal is to eliminate the module and integrate it directly into the battery pack, we need to understand the purpose of the module.
A module is a collection of related components that form a unit; it can also be understood as a collection or assembly of parts. For example, the front-end radiator module in a traditional vehicle, and in the electronics industry, functional integration modules are also called modules. In the realm of battery packs, integrating several cells, busbars, sampling units, and necessary structural support components to form a module is also called a module.
ternary lithium-ion battery module
Early power lithium-ion battery packs used cylindrical cells; for example, Tesla used more than 7,000 cells. If these cells were directly assembled into the battery pack, the assembly complexity would increase significantly, and the processing efficiency would be very low. Therefore, pre-assembling some of the cells became crucial. This is one of the main reasons for the emergence of battery modules.
Another advantage of the modular design is that it facilitates after-sales maintenance and allows for the replacement of individual modules or entire modules.
Like two sides of a coin, the use of modules also necessitates the addition of some extra components, and the more modules there are, the more additional components there will be. These additional components will increase the cost and weight of the battery pack.
Tesla is similar. Initially, Tesla used more than 10 modules, but now the Model 3 only uses 4 large modules, greatly reducing redundant components. In addition, the use of large-capacity square aluminum-cased cells, cell technology innovation, and improved processing consistency have also provided opportunities for eliminating modules.
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CTP has clear advantages in reducing costs and increasing density.
What are the effects of canceling the module?
CATL's data shows that CTP battery packs have increased volume utilization by 15%-20%, reduced the number of battery pack components by 40%, improved processing efficiency by 50%, and increased battery pack energy density by 10%-15%, reaching over 200Wh/kg, significantly reducing the manufacturing cost of power lithium-ion batteries.
According to data from Honeycomb, compared with the traditional 590 module, the first generation of CTP reduced the number of components by 24%, while the second generation improved assembly efficiency by 5-10%, space utilization by 5%, and further reduced the number of components by 22%.
It's difficult to discern the superiority of one technology from just two sets of promotional data, but both CTP companies have demonstrated impressive performance in reducing components and increasing energy density.
Another advantage of module-less manufacturing is the simplification of the product processing flow. A representative from Svolt Energy explained to *Electric Vehicle Observer* that traditional technology involves assembling battery cells into modules using a specific frame structure. These modules then undergo off-line testing, followed by storage and transportation. If the PACK and module are not located in the same factory, additional storage, incoming inspection, and on-line inspection processes are required. All these processes necessitate investment of manpower, equipment, and space.
Adopting a module-less approach can effectively shorten production lines and reduce process waste. Cells are stacked and tested online, and placed vertically into the battery casing, significantly reducing the number of transfer steps and minimizing the traditional module frame welding process. The welding equipment alone costs several million yuan.
Several concerns from industry insiders
Many industry insiders believe that CTP is not a new technology. In the past, it was mostly used in lithium iron phosphate batteries and buses. Because buses have a large battery layout space, lithium iron phosphate batteries have strong stability and are widely used.
However, unlike the combination of buses and lithium iron phosphate batteries, CTP technology will mostly be used in passenger vehicles, most likely with ternary lithium batteries. For example, CATL's cooperation with BAIC New Energy uses ternary lithium batteries. Because of this, some industry insiders have raised several concerns about this technology.
○ Ternary lithium batteries have poor thermal stability. How can their safety be improved?
According to Mr. Ma, a representative from a battery system manufacturing company, in traditional battery packs, the distance between modules serves as a means of heat dissipation. The modules themselves also have thermal insulation designs, taking targeted measures against heat flow, airflow, and ejected conductive materials that may result from thermal runaway of individual cells, thus suppressing the propagation of thermal runaway to some extent. With CTP becoming a large module, will this reserved space be insufficient?
According to the technical staff at Honeycomb, the advantages of CTP lie precisely in its excellent heat dissipation and insulation. Early modules used lithium iron phosphate cells to form VDA-standard modules with a length of 355mm. Due to their high stability, sufficient heat insulation gaps were not considered. Later modules, similar to Volkswagen's MEb standard with a length of 590mm, were limited by the specifications, which restricted the selection of heat insulation buffer materials between the cells. Only small-sized, high-performance materials could be sought, which required relatively high costs to meet safety requirements.
The technician added: "Comparatively, CTP can provide more space by reducing some components, and its own size is less restricted, so it can obtain relatively large clearance space, which allows for more possibilities in material selection, thereby reducing costs."
CATL's solution to this issue is still unclear. However, a battery department head at a relevant automaker revealed that CATL has reserved some space in the battery pack for heat dissipation, and the overall effect is acceptable.
Will CTP affect lifespan?
For ternary lithium batteries, traditional modules have a pre-tensioning force design (cells expand after cycling; if not properly restrained, lifespan will be affected; excessive restraint will also reduce lifespan or cause safety issues) to ensure battery lifespan, and this pre-tensioning force has been tested and verified. The multi-cell integrated design of CTP adds the difficulty of setting the pre-tensioning force. Will this affect the lifespan of the cells?
In response, Svolt's technical staff stated that Svolt's CTP technology inherits the relevant experience of traditional module integration. It applies a certain pre-tightening force to the cell directly through the casing, while utilizing the advantages of flexible space to allow the cell to expand appropriately, thereby improving the impact of integration on cell life and enhancing the lifespan of the battery system.
Will after-sales maintenance costs and the difficulty of reusing the equipment increase?
Mr. Ma believes that traditional battery packs have internal modules, so problems can be resolved by replacing the battery modules. However, if a battery pack without modules malfunctions, does the entire pack need to be replaced? This is likely beyond the capabilities of a 4S dealership and would probably require returning it to the battery manufacturer for repair, significantly increasing after-sales costs.
Han Feng, deputy chief engineer of new energy power technology at Changan Automobile Oushang Research Institute, also stated that not all cells in retired power lithium-ion batteries are damaged. In traditional battery packs with modules, as long as the modules with damaged cells are identified, the other undamaged modules can be directly reused. However, without modules, the difficulty of removing damaged cells increases, making reuse much more complicated.
Regarding the two issues mentioned above, it is unclear whether CATL has any solutions. However, Svolt Energy stated that their CTP technology has already considered this issue. On the one hand, they ensure cell consistency through strict process control to reduce the failure rate; on the other hand, their CTP can achieve cell disassembly to a certain extent, facilitating maintenance and reuse.
In fact, if a single faulty cell can be accurately identified, and the individual cell can be disassembled and replaced by frontline repair personnel, the repair cost will definitely be lower than replacing the entire module.
Could this become a development trend?
Several concerns have arisen among industry insiders: While it seems there are solutions for modular battery packs, will this approach truly be accepted by more and more OEMs?
Han Feng frankly admitted that this technology remains highly attractive to the company. CATL's power lithium-ion batteries using this technology are no longer prohibitively expensive, reaching a level comparable to second-tier battery companies. Naturally, vehicle manufacturers would prefer to purchase better products at lower prices.
Han Feng believes that as an OEM, the first thing to consider is to reduce costs, especially with the significant reduction in subsidies. The cost pressure on vehicle manufacturers will be directly transmitted to battery companies, and battery companies will definitely need to find ways to cope.
Currently, some battery companies' CTP (Cost-to-Pack) solutions can reduce battery pack costs by approximately 0.1 yuan/Wh. This reduction is significant, especially in the lithium iron phosphate battery sector, where price requirements are extremely stringent.
