JIASHAN, China, Jan. 10, 2024 /PRNewswire/ — In recent years, continuous innovations in new energy vehicle battery technology, from cell to system levels, have elevated the performance of new energy vehicles in terms of range, fast charging and safety. As the structure of power cells evolves between prismatic, blade, and large cylindrical shapes, the power battery system has also undergone advancements such as CTP and CTC structures. Cells of various shapes influence space utilization, safety design of the battery pack as well as the integration efficiency and costs of the battery system.
Cylindrical cells, with advantages such as standardized dimensions and wide applicability, can balance high capacity with fast charging capabilities. This resolves concerns related to insufficient range and long charging times for passenger electric vehicles. With these advantages, cylindrical power cells have been recognized by automobile OEMs such as Tesla and BMW. With endeavors from the upstream and downstream links of the industrial chain to fully support technology breakthroughs, cylindrical cells will be installed on a large scale soon.
Entering the cylindrical domain, BatteroTech has brought forth the BTL cylindrical cells based on the “Mercury” technology. The major components of the battery cells adopts the AAS cladding, addressing gas generation issues and ensuring safety. Additionally, BatteroTech’s cylindrical cell has high capacity and fast charging capabilities, with an energy density of up to 280Wh/kg and fast charging time within 15 minutes.
BatteroTech officially unveiled its BTL cylindrical battery system to accelerate the installation of cylindrical cells in electric vehicles. It establishes a safety fortress for the cylindrical battery system through side impact safety, bottom ball impact safety, thermoelectric separation, and heat diffusion suppression.
01 Inherent Safety of Cylindrical Cells Reinforces System Safety
- 1.1 Inherent Safety
The inherent safety advantage of large cylindrical cells lies in the cylindrical shape, which acts as an excellent pressure vessel. The internal structure of cylindrical cells is more uniform compared to prismatic and pouch type. Additionally, the smaller individual capacity of each cylindrical cell, exemplified by BatteroTech’s 4695 series with a capacity of 32Ah, results in 20%-25% less energy release during thermal runaway compared to other forms in the same system, which reduces thermal hazards.
- 1.2 Lower Heat Generation
According to the system-level thermal principles, the heating power of a 160Ah prismatic aluminum cell is I²•R1, while the heating power of a 32Ah cylindrical cell with 5 parallel connections is（I/5)²•R2•5. Assuming equal heating power, it is calculated that 5•R1=R2. Hypothesize that the internal resistance R1 of the 160Ah prismatic aluminum cell is 0.6 mΩ, then the internal resistance of the 32Ah cylinder cell is 3mΩ, meaning the two types of cell are of equal thermal power. In actual operations, the internal resistance of BatteroTech’s 32Ah cylindrical cell can be kept within 2mΩ thanks to all-tab processing, which means the cylindrical cell decreases the thermal power by more than 33% compared with the prismatic cell. This has helped avert the problems of large thermal energy and the middle thermal position in large-capacity cells, increase the temperature uniformity between cells, and lengthen the cell’s cycle life.
- 1.3 Simplified Expansive Force Management and Lengthen Cycle Life
Regarding battery processing, during circular winding of the pole piece of the cylindrical cell, the expansive force at all positions of JR is uniform and wrinkle-free, decreasing risks of wrinkling and lithium precipitation and enhancing safety. The honeycomb patterns between cells isolate them from each other, eliminate the transmission and accumulation of the battery cells’ swelling force, and lengthen the cycle life of cells.
- 1.4 High Strength and Anti-collision
The combination of cylindrical cells in a flexible “honeycomb-like” array enhances mechanical strength and anti-collision performance of the battery pack. The lateral anti squeezing capability exceeds twice the national standard, with resistance to a bottom ball impact of 120J, further reinforcing the safety of the large cylindrical system with the vehicle body.
- 1.5 Inhibition of Thermal Propagation
The honeycomb gaps between battery cells in the battery pack are filled with thermal insulation colloids to reduce the risks of thermal propagation between cells. With the support of the thermal insulation colloids, at the occurrence of the thermal runaway of triggered cells, the measured peak temperature of cells remains below 180°C, and no thermal propagation was triggered in real testing. The dual support of the inherent safety of the single cell and the system-level multifaceted thermal propagation inhibition design ensures the safety of the cylindrical battery system.
- 1.6 Thermoelectric Separation and Smoke Exhaust Design
It is well-noted that the thermoelectric separation and exclusive smoke exhaust design of BatteroTech enable the separation of the high and low voltage connection at the battery cell top and the eruption gases resulting from thermal runaway at the battery cell bottom to avoid electric arc and short circuits. The layer of a smoke exhaust path at the battery pack bottom helps cool down temperatures as well. Upon being cooled down by the smoke exhaust path, the smoke gases are ultimately discharged at a temperature below 100℃ from the explosion relief valve of the box, reducing thermal hazards. The electrical compartment and cooling pipe compartment within the battery pack are mutually isolated, ensuring the safety separation of the circuit and water pathways.
02 Cylinder Selection & CTP/CTC Technology Advancements Bring Multiple Cost Reductions
- 2.1 High Production Efficiency Enables Low Costs
Why is the cylindrical cell favored? With 30 years of development, a standardized production process has been established, and the winding process is highly mature, with high automation and consistency, guaranteeing the high yield and efficiency of cylindrical cell production. The production cycle of cylindrical cells is 26% shorter compared to prismatic aluminum or blade processes. Cylindrical cells eliminate the need for alignment of the tab, preheating, hot pressing, and Mylar film wrapping processes, thereby improving production efficiency (the current industry standard for large cylindrical cell production cycle is up to 300PPM). This helps downstream new energy vehicles achieve economies of scale and cost reduction.
- 2.2 Product Standardization Brings Down Costs
Furthermore, leveraging the standardization and platform advantages of large cylindrical battery cells, BatteroTech can match different energy capacities (80kWh~120kWh) and voltage platforms (350V/400V/650V) based on the same capacity cell. This makes it possible for one cell design to meet various customers’ needs, ultimately reducing the cost of the cell.
- 2.3 Cost Reduction and Efficiency Enhancement through CTP/CTC Applications
In the meantime, as the performance and cost reductions of large cylindrical batteries in new energy vehicles have been widely validated, attention has turned to technical innovations at the system level. CTP integrates cylindrical cells directly into the battery pack, eliminating the need for traditional module components. BatteroTech’s large cylindrical system achieves an 80% weight efficiency for assembled groups and a system energy density of 224Wh/Kg. CTC, an advanced integration of CTP, replaces partial parts of the vehicle chassis with the battery pack shell, further enhancing integration efficiency and helping to compactly integrate the battery pack with the entire vehicle, reducing system costs.
03 Capacity Resonance, Accelerating the Industrialization Process of Cylindrical Cells
In terms of production capacity planning, BatteroTech officially launched the Phase I project in Jiashan, Zhejiang Province in June 2022, and the Phase II was signed on January 28th, 2023. After its completion, the total production capacity will increase to 32GWh. In March 2023, BatteroTech’s 45GWh expansion project in Jiashan was officially signed, planning to build 16 cell production lines. According to the pace of capacity release, it is expected that the third-phase project will be fully completed in 2024, achieving an annual capacity of 77GWh. Leveraging the advantages of large cylindrical standardization in production, BatteroTech can rapidly plan mass production in the future, driving the production of battery systems.
For more information, please visit BatteroTech’s official website: https://en.batterotech.com/
BatteroTech Co., Ltd. is a lithium-ion battery manufacturer dedicated in the new energy industry which is invested by Tsingshan Holding Group Co., Ltd. (a Fortune 500 corporation).
BatteroTech is dedicated to R&D, production and marketing of lithium batteries, battery modules, battery systems, etc. and committed to providing world-class solutions and services for global new energy vehicle manufacturers and electric power investors who aim to achieve the goal of “Carbon Peaking and Carbon Neutrality”. BatteroTech has set up R&D Center and manufacturing Base both in Shanghai and Jiashan, Zhejiang Province.
Source : BatteroTech's BTL Cylindrical Battery System Accelerates the Industrialization of Cylindrical Cells
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