UK-Israel battery technology startup Addionics is highlighting the importance of the pouch cell form factor over the prismatic and cylindrical alternatives.
With their cylindrical shape and build, cylindrical cells are one of the first types of mass-produced batteries and to this day continue to be made in high volumes and dominate certain applications. On the other hand, prismatic cells gained popularity due to their large capacity, thin profile and effective use of space. Their prismatic shape makes it easy to connect multiple cells together, creating a bigger battery pack. Finally, pouch cells, with their sealed flexible foil acting as the container, are known for having a more lightweight structure, says Gilad Fisher, marketing director of Addionics.
In 2020, the total usage in the passenger vehicle market was around 147 GWh in a $17bn market. This was split with 40 percent prismatic, 35 percent pouch and 15 percent cylindrical. This is based on the top six suppliers: LG, CATL, Panasonic, Samsung, BYD and SKI. The remaining 10 percent from the Tier 2 players may also be split within the three formats.
Addionics’ additive technology is compatible with all formats and improves mechanical stability by embedding layers and has additional benefits for pouch cells. This benefits the most from Addionics and is also one of the dominant formats for next-generation batteries. This combined with the natural abilities of pouch cells ensures for one of the most adaptable and powerful batteries on the market.
The technology is currently embedded in pouch cell batteries in three different chemistries: LFP (lithium iron phosphate), silicon and solid-state, and is also compatible with other formats.
Whilst each type of battery cell is better suited to different situations, the cylindrical cell has proven to be the most convenient and adaptable in many ways despite its limits. However, pouch cell usage is growing thanks to its flexibility and overall optimization, and is set to dominate the automotive market.
According to a recent report, the global Cylindrical Lithium Ion Battery market was valued at just under $8bn in 2019. With high mechanical stability, the cylindrical cell is mostly produced with optimized automation processes and techniques, increasing consistency and lowering the cost per unit. Indeed, many manufacturers can provide this type of battery cell which creates product uniformity. That means that if a business’ supplier cannot deliver for any reason, they are sure to find another one producing the same product in terms of performance and dimensions. This makes it easier to switch.
However, due to its shape, it is not possible to fully use the space available in the battery pack, leading to the lower packing density of the cylindrical cell. With a 4680 cell with 25 Ah capacity, as Tesla presented last year, the cell count is 4 times that of a 100 Ah flat cell for the same pack capacity which in turn increases the overhead for the battery management system.
Used mainly in consumer electronics and EVs, the prismatic cell’s packing advantages lie in its layered approach to materials. Their shape resembles a box of chewing gum or a small chocolate bar and though they exist in different sizes, there is no universal format and each manufacturer designs its own.
The soft aluminium coating of a pouch cell allows for a more lightweight battery and depending on the use, an adaptable size and available space says Fisher. This leads to flexible cells that can easily fit the available space of a given product. In terms of space optimization, this translates to between 90%-95% packaging efficiency and increased energy density. By moving to more convenient designs, pouch cells have the potential to match the next-generation performance batteries to accelerate the electrification needs of EVs and consumer electronics.
A limitation of the pouch cell format lies in the lack of standardization, impacting costs to produce and selling prices. As the development of the pouch cell continues, it will become more available, adoption will increase and it will be more widely used. Indeed, standardization will improve production, efficiency, lower costs and increase volumes all whilst optimizing performance.
Additionally, the pouch cell still has some optimization to do as it has lower mechanical resistance and can suffer from potential expansion due to ageing caused by gas development.
Whilst the cylindrical cell has come to a point where it reached its limit in increasing energy density, says Fisher it won’t disappear from the market either. Instead, the pouch cell will have a more dominant stake in the battery market, especially once more development and investment have been put in and it becomes more mass-produced.
Pouch cells are also set to be used the most because the battery considered to be the holy grail of EV batteries, solid-state, can only work in the pouch cell format. Therefore as solid-state is commercialized, with experts talking about 2025-2030, it will be embraced by the industry, meaning that batteries will be adapted to the pouch format.
Looking forward, it appears that as the pouch cell is optimized and moves to higher volume production, flat formats (pouch and prismatic) will be the most used, especially for automotive and energy storage use.
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