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The power battery industry is currently undergoing continuous technological innovation and practice, leading to the emergence of numerous innovative solutions and achievements in battery system integration. One of the key focuses in internal battery integration design is the concept of "fewer components," which involves reducing or eliminating internal modules and other structural components within the power battery. This, in turn, increases the available space for battery cells and enhances the energy density of the battery system.
This article explores how Cell To Pack (CTP) technology optimizes battery structure, increases energy density, and reduces weight. It also discusses the advantages and disadvantages of this technology and introduces the blade battery as a representative of the Cell To Pack integration.
What is Cell To Pack technology?
Cell To Pack (CTP) technology eliminates or reduces the traditional three-level Pack structure of "cell-module-battery pack" by integrating battery cells directly into the battery pack. By omitting the module, the technology reduces the number of components, optimizes space utilization, and lightens the overall battery pack, thereby enhancing the battery's energy density. The entire manufacturing process is simpler, and the production cycle is shorter.
The Cell To Pack integration of power batteries is an innovative battery integration solution. In this approach, battery manufacturers bypass the traditional battery module stage, integrating the cells directly into the battery pack, thereby reducing the number of structural components within the pack. This increases the space utilization rate of the battery pack, raises its energy density, and reduces manufacturing costs.
In recent years, with strong support from leading power battery companies, this technology has been widely applied in many popular new energy passenger vehicles. Chinese battery companies have not only led the global development of CTP technology but have also started exporting this technology globally.
Advantages and disadvantages of CTP technology
Lightweighting: The number of components in the battery pack is reduced by 40%, and the utilization rate is increased by 15%-20%. The typical module integration approach is eliminated, directly integrating the cells into the battery pack, significantly reducing the number of structural components (such as module end plates, side plates, high-voltage connectors between modules, low-voltage sampling harnesses, and structures used to secure the modules). This increases the space available for cells, reducing the weight of the battery pack.
High Energy Density: Energy density is increased from both mass and volume dimensions, with battery energy density increasing by 10%-15%. The primary advantage of CTP batteries lies in their high integration efficiency, high energy density, and cost reduction due to fewer components.
Consequently, CTP batteries can store more energy within the same vehicle boundary, thereby increasing the vehicle's driving range. The number of components is reduced by 40% compared to typical module integration batteries, energy density is increased by 10%-15%, and volume utilization is improved by 15%-20%.
Low Cost: CTP technology controls costs, simplifies manufacturing and assembly processes, increases production efficiency by 50%, and reduces defect rates. The simpler structure requires long lasting battery performance, adhering to the "weakest link" principle, where the poorest-performing component directly determines the overall performance.
However, CTP battery packs primarily use bonding for cell fixation, and structural thermal adhesives are difficult to disassemble without damage once cured. If a cell within the battery pack fails, it cannot be replaced individually, resulting in poor overall repairability of the battery pack.
The internal grouping method of the battery pack also dictates that the high-voltage connectors between cells require more complex and larger equipment for welding, leading to higher manufacturing investment costs.
CTP batteries are better suited to meet the demand for longer driving ranges in electric vehicles and are gradually becoming the mainstream choice for high-range models in the new energy vehicle industry.
Blade battery: a representative of CTP integration
The blade battery is another representative solution of Cell To Pack integration. It is named after its long, slender cells that resemble blades. The key design point of the blade battery is also the elimination of the battery module structure through a "fewer components" approach. It uses elongated cells and a design where the cell tabs exit from the sides to achieve an innovative battery system.
The design also reduces or eliminates the use of transverse and longitudinal beams within the battery pack, thereby freeing up the space occupied by these beams. This allows for more cells to be placed within the battery pack, increasing the overall battery capacity, voltage, and driving range while reducing the weight of the battery pack and achieving lightweighting.
The main advantages of the blade battery include high integration efficiency within the battery pack and high volume grouping efficiency. Compared to typical module integration batteries, the blade battery improves volume grouping efficiency by over 15%, simplifies battery pack assembly processes, and reduces production costs. The size of the cells can also be adjusted according to different boundary requirements, making the blade battery widely applicable to various vehicle models.
However, the elongated shape of the blade battery cells increases the complexity of the manufacturing process. The cells and the casing within the battery pack are bonded together, resulting in poor overall repairability and replaceability. If a cell suffers an irreparable fault, the entire battery pack must be replaced, increasing repair costs.
Overall, the blade battery, as an innovative solution for Cell To Pack integration, can increase the lithium ion battery storage and meet the demand for longer vehicle driving ranges. While Cell To Pack integration technology offers numerous advantages, its practical application requires consideration of factors such as cell type, operating environment, and battery pack maintenance to ensure that the battery pack's performance meets real-world needs.
What is the future development trend of CTP integration?
Given that power batteries, especially cells, require significant investment and possess high technical barriers, car manufacturers typically find it difficult to reach these areas. To avoid being constrained by battery manufacturers, car manufacturers aim to control all products outside the cell.
For battery manufacturers, PACK is more profitable than modules, and they have the opportunity to undertake the entire PACK process only after transitioning to CTP solutions. Currently, aside from BAIC, which has announced that its EU5 model will be equipped with CATL's CTP batteries, other companies like BYD are also investing in research and development.
BYD's original Cell To Body (CTB) technology simplifies the structure and reduces the space loss caused by connecting the body and the battery cover, potentially further improving overall space utilization. In this structural mode, the battery serves not only as an energy source but also as a structural component, participating in the transmission and reception of forces within the vehicle.
This can reduce side pillar intrusion during a crash by 45%. BYD's new cell integration method marks a shift from body integration to battery-body integration, which helps improve space utilization and further unlock the performance potential of electric vehicles.
From a structural design perspective, BYD's CTB technology integrates the vehicle floor panel and the battery pack's upper shell into a single unit. The upper cover of the battery and the sill, along with the front and rear cross members, form a flat, sealed surface that seals the passenger cabin with adhesive. The bottom is assembled with the vehicle body through mounting points.
In this design, the battery system is integrated into the body during battery pack manufacturing, ensuring that the battery itself meets sealing and waterproofing requirements, while the sealing between the battery and the passenger cabin is relatively simple, and risks are controllable.
In the future, CTP and Cell To Chassis (CTC)—where cells are directly integrated into the vehicle chassis—will coexist. Vehicle manufacturers with more experience in chassis development will have greater control in the future, while battery manufacturers lacking experience and technical accumulation in vehicle chassis development may lose control over entire projects, disrupting the current dominant position of battery manufacturers. Under the battery-swapping model, the joint efforts of governments and enterprises may promote CTP development in the short term.
Conclusion
Cell To Pack technology demonstrates significant advantages in the power battery field, including lightweighting, high energy density, and low cost. However, as the technology evolves, further optimization of CTP technology and addressing its challenges in maintenance and manufacturing will become important issues for the industry.
As CTP and CTC technologies coexist, car manufacturers and battery companies will seek new cooperation and balance in future competition, paving the way for innovative development in the new energy vehicle industry.
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