Pros and Cons of Lithium Prismatic Cells Vs Cylindrical Cells

Battery cells are designed in various shapes to cater to the needs of different electronic devices and battery-operated applications. Distinct shapes, such as prismatic cells and cylindrical cells, offer various advantages based on specific requirements, whether for cost-effective mass production or for applications needing higher capacity batteries.

Understanding the operational differences between these two battery types is essential. The choice of battery cell considerably influences your product’s design, power availability, and safety in the event of cell failure. By selecting the appropriate cell type, optimal performance and safety for your particular application can be achieved.

Battery Cell Shapes and Sizes

Different battery shapes are engineered to fit various devices and applications. The predominant types are cylindrical and prismatic cells, with each offering unique characteristics and advantages.

Cylindrical Cells

Cylindrical cells are elongated and circular, resembling the familiar batteries used in toys, remote controls, and other devices. They are created by tightly winding electrodes within a specially designed metal casing. This shape holds several benefits:

- Universal Sizes: Cylindrical cells are available in standardized dimensions like 14650, 18650, 21700, and 26500, which ensures compatibility across various applications, promoting interchangeability among manufacturers.

- Structural Strength: The round design evenly distributes internal pressure and electrolytes, thereby reducing the chances of leakage or cell swelling.

- Mass Production: Their simple design and extensive usage make them easy and economical to produce in large quantities.

Prismatic Cells

Prismatic Lifepo4 cells, on the other hand, are flat and rectangular, engineered to optimize space efficiency. They typically consist of layers of electrodes encased in steel or aluminum, with an insulated film covering. This design offers numerous advantages:

- Space-Saving: Their compact structure enhances space utilization within devices, making them particularly suitable for applications where dimensions are crucial, such as in electric and hybrid vehicles.

- Custom Shapes: Unlike cylindrical cells, prismatic cells do not conform to universal size norms. This adaptability permits manufacturers to design unique shapes tailored to specific applications, though it usually involves navigating minimum order quantities and requisite certifications.

However, there are challenges associated with prismatic cells:

- Stress Points: The flat, rectangular design, especially at the corners, may be more vulnerable to stress from impacts and vibrations. If not adequately shielded, these areas could deteriorate over time.

- Electrolyte Distribution: The pointed corners may impede the uniform distribution of electrolytes, potentially resulting in cell swelling and deformation.

Prismatic cells are available in various sizes, and their non-standardized formats often necessitate custom production. This customization can lead to increased costs and demands careful consideration of manufacturing and certification factors.

Voltages And Capacities

Regarding voltages and capacities, both cell forms exhibit distinct pros and cons. Prismatic cells, being larger than cylindrical cells, have fewer connections in the application, allowing for greater capacities. For instance, a single lithium phosphate battery (LifePO4) in prismatic form delivers 3.2 volts and 100Ah.

Conversely, cylindrical cells possess more connections in applications and are available in smaller sizes, resulting in less energy storage. Although they have lower capacity compared to prismatic cells, they excel in voltage power and deliver quicker discharge rates per amp hour (Ah) due to their design requiring more connections.

To attain the same amp hour rating as one prismatic cell, roughly 18 cylindrical cells are necessary. For achieving a voltage of 48 volts, you would need either 18 prismatic cells or 16 sets of 18 cylindrical cells.

Despite requiring more units to match the capacity of prismatic cells, cylindrical cells provide enhanced energy efficiency. This feature makes cylindrical cells ideal for high-performance applications such as toys and consumer electronics, where extended battery life is important. In contrast, prismatic cells are more suited for applications with higher energy demands, including energy storage systems, medical devices, and electric vehicles.

Lifepo4 Prismatic Cells Vs Cylindrical Cells: Which Is Better?

Several factors should be considered when comparing LiFePO4 prismatic cells to cylindrical cells:

Prismatic cells are theoretically able to achieve a higher energy density than cylindrical cells. Their simpler structure and less complex production process contribute to this benefit, as they do not require high-strength stainless steel shells like their cylindrical counterparts. This factor promotes the growing popularity of prismatic batteries in electric vehicle applications.

Prismatic cells also exhibit excellent thermal characteristics, necessitating less cooling per energy unit compared to cylindrical cells. They provide superior cycle life even under varied and high loads, which often degrade other lithium cell formats. With a cycle life up to four times greater than cylindrical lithium cells, prismatic cells can significantly reduce operational and ownership expenses.

In contrast, cylindrical batteries have been extensively developed, leading to a highly mature and standardized technology. Their assembly permits greater spacing between individual cells, enhancing heat dissipation. Numerous models employing cylindrical cells utilize cost-effective air cooling methods.

When deciding between prismatic and cylindrical cells, keep in mind your specific lithium application requirements:

- High Power and Long Service Life: Cylindrical cells are preferred due to their established technology, standardized design, and efficient heat dissipation.

- Limited Space and Cost Considerations: While prismatic cells may entail higher initial costs, they provide compact designs suitable for constrained spaces and lower long-term operational costs thanks to their superior energy density and longevity.

Ultimately, your choice should reflect your priorities—whether it's maximizing energy density and cycle life with prismatic cells or utilizing the dependable technology and heat dissipation strengths of cylindrical cells.