Winding vs stacking battery – which one is best

Winding vs stacking battery, which is best?
There are two processes in the middle process of lithium battery preparation: winding vs stacking battery.
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    There are two processes in the middle process of lithium battery preparation: winding vs stacking battery. Winding is to shape the long pole pieces in a rotating manner, and the positive and negative pole pieces are continuous. The lamination is formed by stacking the slit positive and negative electrodes.

    There are also differences in the die-cutting process between winding and lamination. Winding mainly cuts the non-coating area. From the perspective of efficiency and cost, laser die-cutting is mainly used. The lamination still needs to be combined with hardware die-cutting because it needs to cut the coating area.

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    The stacking battery in the battery market is expected to increase

    In the application of power and energy storage batteries, cylindrical batteries can only use the winding process due to the restriction of shape design. Rectangular and pouch batteries can be either wound or laminated. From the practical application in the past, the stacking process is mainly used by South Korean battery factories such as LGES and SKI, while domestic square batteries mostly use winding schemes. 

    However, with the launch of the blade battery solution, the increase in battery capacity and the advancement of the stacking process, the competition winding vs stacking battery of prismatic batteries has once again attracted market attention. In this regard, we also analyze the advantages and disadvantages of the two routes and the progress of industrialization.

    What are the advantages and disadvantages of winding vs stacking battery

    From the perspective of lithium battery performance, the lamination process is theoretically more dominant in energy density, cycle life, and rate performance. One is that due to the curved C angle in the winding process, the space utilization of the battery cell will be lower than that of the laminated battery. 

    Moreover, the bending of the pole piece will cause uneven stress during charging and discharging, causing deformation and twisting, thereby affecting the cycle life of the battery. The second is that the number of tabs in the lamination scheme is twice that of the winding scheme, which can reduce the electron transmission distance, reduce resistance, reduce heat generation, and the current distribution is uniform, which can improve the cycle life and rate performance of lithium batteries.

    What are the advantages and disadvantages of winding vs stacking battery?

    From the perspective of industrial control, the difficulty of winding is that it is necessary to ensure that the alignment of the positive and negative electrodes and the separator is controlled within ±0.5mm, otherwise short circuits will easily occur. In addition, in the case of bending and deformation of the pole piece, problems such as powder dropping and burrs must be controlled, which also puts forward higher requirements for production and preparation. The lamination process is more complicated than the winding process in the slitting process, and the control requirements for the section and burrs of the pole piece after slitting are very high. Otherwise, it will affect the yield and consistency of the battery, and then affect the performance.

    From the perspective of production cost, the production process of the winding process is relatively simple, with a high degree of automation and an advantage in production efficiency. The lamination process needs to increase the number of slitting, burr removal and other processes, and the stacking efficiency is lower than that of winding, so the production efficiency is lower than that of winding. At the same time, because the investment cost of lamination equipment is higher, it also makes winding vs stacking battery economically superior.

    In short, the stacking process can improve the overall performance of lithium batteries. However, it still faces the problems of production yield, consistency and production cost. Therefore, winding is still the current mainstream route, but the future of lamination can be expected.

    The market situation of winding vs stacking battery

    With the product iteration of lithium batteries in terms of product form, cell capacity, and cycle life, as well as the technical progress of the lamination process itself, the increase in the penetration rate of the lamination process is worth looking forward to.

    The market situation of winding vs stacking battery

    The first is the change in product form. The square battery was previously “brick-shaped”, and the length of the mainstream single battery cell is in the range of 140mm to 300mm. In 2020, BYD launched a blade battery with a length of 1m, and SVOLT subsequently launched a short blade battery with a length of about 600mm. 

    The blade cell can bring about an increase in the energy density of the battery volume and a higher group efficiency, and is a competitive product solution. Due to the length factor of the blade battery cell, only lamination technology can be used in the process. In the future, the increase in the volume of blade battery products will drive the increase in the penetration rate of the lamination.

    From the perspective of the application of power battery companies, BYD and SVOLT are actively promoting the blade battery solution, and will also introduce the entire system into the stacking process. CALB, EVE, and Volkswagen Group’s next-generation technology solutions, although they have not yet reached the length of the blade in terms of product specifications, from the perspective of battery performance, the choice of the stacking route has also been clarified.

    The second is the change of battery capacity. The increase of battery capacity is an important way to reduce battery cost and increase energy density. The 250-300Ah of a single battery is already relatively limited. Currently, 280Ah batteries are the mainstream for energy storage batteries, and batteries with larger capacities of 300Ah and even 560Ah are also coming out one after another.

    EVE released the 560Ah energy storage large battery cell LF560K

    With the increase of battery capacity, the disadvantages of the C angle of the winding scheme will gradually appear. Including the impact of space utilization on energy density, and the improvement of preparation requirements for pole piece bending and pole piece alignment accuracy. The lamination scheme will be more suitable for large-capacity batteries. Therefore, when EVE released the 560Ah energy storage large battery cell LF560K in October 2022, winding vs stacking battery, it chose the stacking scheme.

    According to calculations, when the current lamination process has a single-chip efficiency of 0.6-0.7s/piece and a cell capacity of 200-280Ah, the investment in single-GWh lamination equipment is 50-60 million RMB. However, with the improvement of lamination efficiency and the increase of battery capacity, the investment in lamination equipment will decrease significantly. Assuming that the lamination efficiency reaches 0.2s/piece, for a 280Ah cell, the cost of lamination and winding will be relatively close. If the cell is of a larger size, the cost of lamination may be more advantageous.

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    Anna
    I’m Anna and I have worked for years in battery manufacturing industry. Introducing professional batteries knowledge, especially in lithium-ion battery with a solid background, I enjoy sharing ideas with people at all stages if they are interested or work in energy industry. I now help you understand the most advanced technology about batteries and bring you the latest news in this industry .

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