The future of Energy Storage: Large Cylindrical Lithium-ion Batteries

Recently, EVE energy announced that it will start mass production and delivery of its 46 series large cylindrical batteries from September 2023. This news has drawn the market's attention to the potential of large cylindrical batteries.

As the new energy industry demands higher battery energy density and lower cost, cylindrical lithium-ion batteries are evolving towards larger sizes. In 2020, Tesla pioneered the development and production of the 4680 type (46mm in diameter and 80mm in height) large cylindrical battery, setting a new standard for the industry's transition to large cylindrical batteries.

In recent years, cylindrical lithium-ion batteries have grown from the initial 18 series to 21, 26, 32 series, and even 40 series have emerged in the market in the past two years. Global battery manufacturers have begun to invest in large cylindrical batteries to meet the needs of the energy storage and power systems sectors.

Compared with small cylindrical batteries such as 18 and 21 series, large cylindrical batteries have not only increased in size but also changed in internal structure. For example, the 18, 21, and 26 series usually adopt the conventional single-tab design, while large cylindrical batteries use multi-tab or full-tab technology.

Moreover, large cylindrical batteries have obvious advantages over small cylindrical batteries in terms of performance. First of all, cylindrical batteries require high BMS technology, and large cylindrical batteries reduce the complexity of BMS control due to fewer cells. Secondly, the reduced cell count can also reduce the use of structural components, increase the apertures of support plates and current collectors, improve the grouping efficiency, and make up for the low grouping efficiency of small cylindrical batteries. Thirdly, thanks to the high-strength steel shell design of large cylindrical batteries, they have minimal impact on cell expansion and deformation, and have excellent impact resistance and reliability in various environments. Fourthly, the multi-tab or full-tab design greatly shortens the distance of electron movement, reduces the ohmic resistance of the battery, and improves the rate performance of the battery. Fifthly, the larger size of large cylindrical batteries is conducive to cost reduction in the industry. Upgrading from 21700 cells to 46800 cells can reduce unit production costs by 14%.

However, there are also significant technical and manufacturing barriers for large cylindrical batteries. The increase in volume brings greater challenges to radial and axial geometric symmetry manufacturing difficulties and strict requirements for positive and negative tabs. The flattening, welding, and injection of full-tabs pose great technical challenges and increase the difficulty of manufacturing. In addition, due to the larger single-cell volume, internal heat dissipation becomes more difficult.

Industry experts believe that 2023 may be the year of large cylindrical battery expansion. In early 2023, Tesla announced that it would build two new factories near its Nevada production base in the United States, one of which would produce its latest 4680 batteries.

According to incomplete statistics from the Energy Storage Application Branch of China Chemical and Physical Power Industry Association, major domestic battery companies such as CATL, Eway Li-Nergy, Penghui Energy, Langtaitong Technology, Guoxuan High-Tech, Haichen Energy, Bik, and Baolixin have all made plans for large cylindrical battery development. CATL stated at its 2022 annual performance briefing that it had successfully developed 4680 and other large cylindrical batteries. In 2021, Eway Li-Nergy launched its 40 series large cylindrical batteries for household energy storage applications. Penghui Energy started mass production of its 40 series large cylindrical batteries in 2022. Langtaitong Technology's 32 series large cylindrical batteries entered mass production in 2016 and their product performance has been recognized by various customers in energy storage and small power sub-markets. The mass production of domestic 4680 large cylindrical batteries is also imminent.

Preliminary data shows that China's shipment volume of large cylindrical batteries in 2022 was close to 160 million units. In the first half of 2023, this number had already reached about 110 million units. These batteries are widely used in key market segments such as lead-acid battery replacement, portable energy storage devices, household energy storage systems, low-speed electric vehicles, smart homes, and robotics, among other fields.

The future development trend of large cylindrical batteries is the 4680 type battery. Eway Li-Nergy recently stated during a research survey that major global automakers are highly interested in large cylindrical batteries, and the consensus is that the 46 series large cylindrical batteries will become one of the mainstream power batteries in the future. However, widespread application will still take some time. In fact, many non-power battery manufacturers, including Bik and Langtaitong Technology, are actively developing 4680 type batteries to meet specific application needs.

As technology advances, the cycle life of large cylindrical batteries is expected to reach 5,000 cycles or even higher. This means that the batteries can withstand more charge and discharge cycles, providing longer service life. Although square-shaped batteries also have application potential, they do not have advantages in manufacturing efficiency and cost within the capacity range of less than 50Ah. At this point, large cylindrical batteries (not only the 4680 type but also sizes of 32 and above) show their unique competitive advantages.

In summary, large cylindrical batteries, with their outstanding performance stability, impact resistance, manufacturing processes, and cost advantages, have great potential and advantages in the field of energy storage. As technology progresses and market demand grows, large cylindrical batteries will play an increasingly important role in the future of energy storage. Industry experts believe that "the current large cylindrical battery industry chain is in the pre-dawn breakthrough stage, and the global demand for large cylindrical batteries in 2023 is expected to be about 23 GWh, with the potential to exceed 250 GWh in 2026."

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