Cylindrical & Prismatic LiFePO4 Cells, who wins?
The shape of the battery affects the overall performance of the entire battery pack, no doubt. When it comes to DIY energy storage, prismatic LiFePO4 cells and cylindrical LiFePO4 cells are the most popular. There are obvious advantages to both types of cells, so choosing the right cell is crucial.
What are Cylindrical & Prismatic LiFePO4 Cells?
The cylindrical shape of LiFePO4 cells makes them easy to produce. This is the initial appearance of all mass-produced lithium batteries. Because of this, the cylindrical shape is also the shape of lithium batteries with the longest history and largest size.
The prismatic LiFePO4 cell is a relatively new type of battery shape. It is said that the prismatic LiFePO4 cell is the product of the development of the electric vehicle industry. In general, this type of battery does not be widely used in general energy storage scenarios because of its large capacity and attention to space utilization.
The pouch battery shape has a higher utilization rate, but is not as popular as cylindrical LiFePO4 cells and prismatic LiFePO4 cells for some reason.
What’s Different Between Cylindrical & Prismatic LiFePO4 Cells?
Space Utilization
Cylindrical and prismatic LiFePO4 cells utilize space differently. Prism-shaped cells can be arranged closely, whereas cylindrical cells are inevitably spaced apart.
The Life Span
As a result of the different manufacturing processes, the cylindrical LiFePO4 cell will have slightly more cycles than the prismatic cell.
Weight
The majority of cylindrical cells have steel shells, whereas most prismatic cells use stainless steel and aluminum shells.
Manufacturing Cost
The manufacturing cost of cylindrical cells will be relatively lower due to their long history and simpler production and processing technology, while prismatic cells are relatively new and have limited processing technology and no special standardized production specifications, so their manufacturing costs will be higher.
Damage Cost
At the same capacity, damage to a prismatic cell will severely affect the entire battery pack. At the same capacity, damage to a cylindrical cell will not seriously endanger the entire battery pack.
Energy Density
The structure determines the energy density of prismatic LiFePO4 cells, which is slightly higher than that of cylindrical cells.
Easy to Expand
Since most scenarios currently require large-capacity batteries, the option of capacity expansion has become a consideration for many people. However, expanding the capacity of cylindrical cells is more challenging than expanding the capacity of cylindrical cells. A cylindrical cell may need tens of thousands of cells with the same capacity, but a prismatic cell may only require a few, thereby requiring fewer cells. In contrast, prismatic LiFePO4 cells can be expanded more easily.
Differences in Chemical Activity
Because of the cylindrical cell’s internal structure and shape, electrolytes are distributed uniformly inside the cell, allowing it to be fully utilized. In the inner corners of the prismatic cell, some electrolytes will be in an idle state, and the prismatic structure will exert some pressure on the corners. In summary, the electrolyte will not be utilized very much.
Heat Dissipation
Because cylindrical cells cannot be arranged as closely as prismatic cells, and there are gaps between them, cylindrical cells will dissipate heat better.
Battery Pack Stability (with BMS)
Due to the smaller number of cells in the battery pack, prismatic LiFePO4 cells will provide better system stability, since the BMS can serve each cell independently.
Summary
Overall, both cylindrical and prismatic LiFePO4 batteries have their own advantages and disadvantages, depending on the application. Currently, the development of the latter is rapidly increasing with many manufacturers investing great resources in research and development to improve its current limitations. Therefore, it can be anticipated that prismatic LiFePO4 cells will become the dominant energy storage battery in the near future. As of now, it definitely should be a top option for consideration.