The Square Formation Team Has A Challenger: BMW Is Betting on Large Cylindrical Batteries, And Eve Is Joining Forces To Engage in The Mass Production Battle.

Recently, the battery production base of BMW in Shenyang witnessed the mass production of its sixth-generation large cylindrical battery. Thus, the 46-series large cylindrical battery jointly developed by BMW and Yiliu Lithium Energy has achieved mass production for pure electric passenger vehicles, marking another significant event in the global large cylindrical battery industryization process.

At the press conference, the BMW side announced that the new-generation BMW i3 model equipped with Yiliu Lithium Energy's large cylindrical battery successfully completed a 1,213km real-road charging-free endurance challenge. The low energy consumption data of 8.8 kWh/100km was particularly eye-catching. But what is the real industrial signal behind these data? It is even more worthy of exploration.

The global top-tier luxury carmakers, in collaboration with Yiliu Lithium Energy, have been deeply engaged for many years, bringing large cylindrical batteries from laboratory samples to large-scale production. This is expected to shake up the long-term dominant industrial pattern of square batteries in the automotive sector.

01

Route Choice

BMW broke away from the square-shaped inertia and made a strategic adjustment at the system level of the entire vehicle.

Over the past decade, with its mature manufacturing processes and PACK integration solutions, as well as a complete supporting supply chain, square batteries have firmly held the dominant position in the power battery market for passenger vehicles, forming a huge technological route inertia.

Rao Guang, the vice president of BMW China's R&D department for high-voltage batteries and charging, introduced that from the fifth generation to the sixth generation, it was a return to the starting point and a re-development. Within the BMW organization, from over 20 schemes, after intense debate, they ultimately selected the 46 series large cylindrical cell route.

But this is not simply changing the shape of the battery cells; it is a bottom-level reconfiguration of the vehicle architecture, power supply system, battery packaging, and battery thermal management system. From samples to mass production vehicles, it is actually full of difficulties.

According to him, from the engineering test results, large cylindrical batteries naturally have advantages such as strong shell pressure-bearing capacity, built-in heat dissipation gaps in the cell arrangement, and compatibility with CTC integrated integration. However, their production bottlenecks are also prominent.

For example, the control of the thermal influence zone of the current collector laser welding is very difficult. Even a tiny welding defect could potentially lay down long-term reliability risks.

Therefore, many enterprises in the industry's large cylindrical products still remain at the sample and small-scale trial stage and cannot withstand the long-term durability verification of luxury car manufacturers.

As an international leading carmaker, BMW's choice of the large cylindrical battery route is actually unwilling to passively follow the mature square battery track, but with its high vehicle performance as the anchor, to build a bottom-level battery technology system for the next-generation electrification. Therefore, BMW also has to face the engineering difficulties of large cylindrical battery mass production.

02

Engineering Challenges

0.01 ppm quality control threshold, Yiliu meets BMW's strict standards

BMW set a quality control red line of 0.01 ppm (one in a million) for the sixth-generation battery. You should know that when the project was initiated, the requirement was: the welding pass rate should be above 95%, while the team could only achieve about 30% initially.

The complexity of cell manufacturing is even more unimaginable. It is reported that a battery pack integrates 960 cells, each of which needs to undergo two welding processes and be stacked within a few minutes; the entire package contains over 2,000 welding points and more than 40 areas of gluing, and the product must pass a 1700-volt or higher high-pressure test before leaving the factory. The production line needs to maintain an output rate of approximately 150 pieces per minute, and it also needs to complete nearly 200 quality verification items. It can be seen that the production efficiency and quality control standards on the production line have formed a sharp engineering balance problem.

In terms of component selection, BMW adopted different supply strategies for the battery cells of the new-generation models. Among them, the high-performance iX3 50L top-tier model, the complete set of large cylindrical battery cells is exclusively supplied by Yiliu Lithium Energy. This is the trust vote cast by BMW after multiple rounds of reliability and safety verification and layer-by-layer screening.

According to the data, Yiliu Lithium Energy, relying on its cylindrical battery factory, has refined and accumulated a complete cylindrical battery intelligent manufacturing system. The mature methodological approach of digital twin and AI full-link quality inspection has been migrated and implemented in BMW's Shenyang battery factory. This digital system can predict process fluctuations in real time, reduce the individual differences of the battery cells to within the BMW's standards, and maintain the 0.01 ppm quality bottom line in the battery cell manufacturing process. At the same time, each large cylindrical battery cell retains over 360 image archives to achieve full-process traceability. Combined with the whole-pack X-ray flaw detection test before leaving the factory, it prevents and detects internal and external defects of the battery in the battery cell manufacturing and PACK assembly two processes.

03

Chinese production line experience

Reinforcing BMW's global electric vehicle strategy

As early as around 2021, BMW established a deep partnership with BYD Energy. The sixth-generation battery manufacturing and quality control experience accumulated by BMW's Shenyang动力电池 factory will be transferred and applied to other BMW production bases worldwide.

This cooperation model is no longer "processing according to drawings"， but represents the engineering capabilities of China's battery cell production lines， participating in the construction of BMW's global electrification system as an illustration.

The new-generation i3 1213km extreme range case is a concentrated validation of this cooperation system： BYD supplies stable high consistency battery cells as the hardware foundation， while BMW completes the 800V high-voltage platform， thermal management， BMS energy management and vehicle integration calibration. The hardware and system work together to achieve the ultimate long-range driving range.

According to the plan， starting from 2027， BMW will launch nearly 20 models with the new-generation battery in the Chinese market. At the same time， BMW is evaluating the feasibility of increasing the export of Chinese-produced models to Southeast Asia and other regions. The large-capacity cylindrical battery supplied by BYD Energy is expected to achieve large-scale installation and go global simultaneously.

With the large-scale launch of BMW's new models， large-capacity cylindrical batteries will officially enter the main track of passenger vehicles， facing the comprehensive competition of square batteries. The competition between the two may fall into three core dimensions：

First， cost. Square batteries have over a decade of production experience， with significant advantages in material， equipment supply chain costs； large-capacity cylindrical batteries are still in the early stage of large-scale production， and their cost curve needs to decline with the release of production capacity.

Second， supply chain maturity. Square batteries have a complete upstream equipment and PACK ecosystem； large-capacity cylindrical batteries still need continuous iteration.

Third， long-term reliability. Square batteries have a large amount of vehicle-long-term road data accumulation； large-capacity cylindrical batteries need to continuously collect long-term cycle， aging， and safety condition data to accumulate market verification.

The competition in the battery powertrain field is never a comparison of paper parameters， but a long-lasting battle of production consistency and full life cycle safety. The launch of BMW's sixth-generation battery， and BYD Energy's achievement of the milestone of 100 million large-capacity cylindrical battery production， are just the new starting point of the competition of technical routes.