Lithium Ion Cylindrical Cells Vs. Prismatic Cells

Cylindrical and Prismatic Cells are the best options on the market for building Lithium Batteries. Consider the following advantages and disadvantages of each cell type before you buy the battery for the desired application.

Cylindrical Cells

The cylindrical cell continues to be one of the most widely used packaging styles of today. With its superiority making it easy to manufacture and have excellent mechanical stability. Tubular cylinders can withstand high internal stress without deformation.

Many lithium and nickel-based cylindrical cells include a positive thermal coefficient (PTC) switch. When exposed to excessive current, the normally conductive polymer heats up and becomes resistive, stopping the current flow and acting as short circuit protection. Once the short is removed, the PTC cools down and returns to the conductive state.

Most cylindrical cells also feature a pressure relief mechanism, and the simplest design utilizes a membrane seal that ruptures under high pressure. Leakage and dry-out may occur after the membrane breaks. Re-sealable vents with a spring-loaded valve are the preferred design. Some consumer Li-ion cells include the Charge Interrupt Device (CID) that physically and irreversibly disconnect the cell when activated to an unsafe pressure builds up. 

Prismatic Cells

Introduced in the early 1990s, the modern prismatic cell satisfies the demand for thinner sizes. Wrapped in elegant packages resembling a box of chewing gum or a small chocolate bar, prismatic cells make optimal use of space by using the layered approach. Other designs are wound and flattened into a pseudo-prismatic jelly roll. These cells are predominantly found in mobile phones, tablets and low-profile laptops ranging from 800mAh to 4,000mAh. No universal format exists and each manufacturer designs its own.

Prismatic cells are also available in large formats. Packaged in welded aluminum housings, the cells deliver capacities of 20–50Ah and are primarily used for electric powertrains in hybrid and electric vehicles. Figure 5 shows the prismatic cell.

Prismatic cells are the most popular today due to their large capacity. The shape can connect easily four batteries at once to form a battery pack.

Cylindrical Advantages

The cylindrical cell design has good cycling ability, offers a long calendar life and is economical, but is heavy and has low packaging density due to space cavities.

The cylindrical cell battery has a strong and robust advantage as its casing has protected. Batteries, in this case, are more resistant to working at hot temperatures. Resistance to shocks is also excellent, then this battery is often familiar to use on electric vehicles. Many cells are combined in series and parallel to increase battery voltage and capacity. If one cell is damaged, the impact on the whole package is low.

Typical applications for the cylindrical cell are power tools, medical instruments, laptops, and e-bikes. To allow variations within a given size, manufacturers use partial cell lengths, such as half and three-quarter formats, and nickel-cadmium provides the largest variety of cell choices. Some spilled over to nickel-metal-hydride, but not to lithium-ion as this chemistry established its own formats. 

Prismatic Disadvantages

Prismatic cells consist of many positive and negative electrodes that are flanked together making it possible for short circuit and inconsistency. Prismatic cells die faster because thermal management is less efficient and relatively sensitive to deformation in high-pressure situations. Other disadvantages include a limited number of standard sizes and higher average hourly wattage prices. BMS is also complicated to handle this sell because of the capacity that is owned.

Selecting Your Cell

Most often, choosing your lithium battery’s cell design comes down to space, cost and safety considerations.

If your lithium application requires strong power, performance and longevity with less concern for use of space, consider picking up a cylindrical cell. If overloading becomes a concern, opt for cylindrical’s improved safety profile. However, if your lithium application requires power packed into a small space and you’re able to handle the cost, prismatic is your best bet.

Right now, the cost-effective cylindrical model controls market share. However, as new products create a need for increasingly space-conscious solutions, battery technology advances and prices change, demand for prismatic cells is expected to increase.

If you’re still not sure what type of lithium cell is right for you, consider working with an established partner capable of helping you make a smart buying decision matched to your specific needs.