Cell formats

Battery cells used in EVs are commonly built in three main formats: cylindrical, prismatic, and pouch. The cell format affects manufacturing, packaging efficiency, cooling, mechanical stability, and how the cells are integrated into the battery pack.

No single format is best in every application. Different formats suit different design priorities, including cost, energy density, structural integration, thermal management, and production scale.

Cylindrical cells

A cylindrical cell consists of sheet-like anodes, separators, and cathodes that are layered and rolled into a jelly-roll structure, then placed inside a rigid cylindrical can.

Cylindrical cells have been used in batteries for many years and benefit from mature, high-volume manufacturing. In EVs, they are used in several well-known battery designs, including Tesla applications, and are also being adopted in BMW's latest Neue Klasse battery generation.

Advantages

• Mechanical stability: The cylindrical shape distributes internal pressure well and helps the cell resist deformation.
• High production throughput: Cylindrical cells are well suited to highly automated, high-volume manufacturing.
• Consistent geometry: The fixed shape can simplify cell production and quality control.

Disadvantages

• Lower space utilization at pack level: Round cells leave unused space when packed together unless the pack is designed carefully.
• More pack integration work: A large number of smaller cells can increase pack complexity.

Common sizes

Prismatic cells

Prismatic cells use a rigid rectangular housing, usually made of metal. Inside, the electrodes and separator are either stacked or rolled and packaged into a box-shaped enclosure.

Prismatic cells are widely used in EVs because their shape can make better use of available pack space than cylindrical cells.

Advantages

• Good space utilization: The rectangular shape allows efficient packaging within the battery pack.
• Fewer cells for the same pack size: Larger cell sizes can reduce the number of cells and connections required.
• Strong structural form: The rigid housing helps support cell handling and integration.

Disadvantages

• More complex cell expansion management: Large flat surfaces can swell and require careful pack compression and support.
• Potential stress concentration: Corners and edges can experience higher local mechanical stress.
• Lower standardization: Prismatic cells come in many sizes and designs, which can reduce manufacturing commonality.

Pouch cells

Pouch cells use a flexible laminated foil instead of a rigid metal can. Internally, the electrodes are usually stacked, and the flexible outer pouch helps minimize inactive material and weight.

Pouch cells can offer high packaging efficiency and low weight, which makes them attractive in applications where space and gravimetric efficiency matter.

Advantages

• High packaging efficiency: Pouch cells can reduce inactive material and use pack space efficiently.
• Low weight: The flexible enclosure is lighter than a rigid metal housing.
• Flexible sizing: Pouch cells can be produced in a wide range of shapes and dimensions.

Disadvantages

• Swelling: Pouch cells require careful compression and pack design to manage expansion over time.
• Lower inherent mechanical protection: The flexible enclosure provides less structural support than cylindrical or prismatic housings.
• Greater pack-level support requirements: The surrounding pack structure must do more of the mechanical work.

Blade-type cells

Blade cells are best understood as a specialized long, thin prismatic cell design rather than a completely separate fundamental format.

BYD's Blade Battery is the best-known example. It uses long LFP cells that are integrated efficiently into the battery pack, helping improve space utilization, structural efficiency, and thermal behavior.

Advantages

• Efficient pack integration: The long, narrow cell shape can improve pack-level space utilization.
• Good thermal characteristics: The geometry can support effective heat dissipation.
• Strong safety reputation: Blade-type LFP designs are closely associated with high thermal stability and robust pack design.

Disadvantages

• Less flexible across all pack layouts: The long-cell format suits some architectures better than others.
• Design is closely tied to pack concept: Many of the benefits depend on the full battery-pack architecture, not only the cell itself.

Summary

Cell format is an important part of battery design because it affects cost, pack efficiency, cooling, durability, and manufacturing strategy.

• Cylindrical cells are strong, standardized, and well suited to high-volume production.
• Prismatic cells use pack space efficiently and are common in EVs.
• Pouch cells can reduce weight and inactive material, but need more pack support.
• Blade-type cells are a prismatic variation optimized for efficient pack integration.

The choice of cell format is therefore not only about the cell itself, but also about how the entire battery pack is designed.