Cylindrical Cells

Cylindrical cells use a wound electrode structure enclosed in a rigid metal can. This format is widely used due to its mechanical robustness and highly mature manufacturing ecosystem.

They are commonly found in standardized sizes such as 18650 and 21700, enabling scalable and repeatable pack designs. These designations refer to the cell dimensions, where the first two digits indicate the diameter (in millimeters), the next two or three digits represent the length, and the final digit denotes the cylindrical shape (0), meaning an 18650 cell is approximately 18 mm in diameter and 65 mm in length.

Strong mechanical stability, well-established supply chain, and compatibility with high-volume automated assembly. The rigid casing makes handling and integration more forgiving compared to other formats.

Lower packing efficiency due to cylindrical geometry, increased number of interconnections at pack level, and less direct thermal pathways compared to flat cell designs.

High-volume EV platforms prioritizing manufacturability and scalability. Examples include the Tesla Model 3 and Tesla Model Y, which use cylindrical cells in highly optimized pack architectures.

Pouch Cells

Pouch cells use a flexible laminated enclosure instead of a rigid casing, typically composed of aluminum-laminated polymer films. This design minimizes inactive material, allowing for higher energy density and more efficient use of available space within the battery pack. The flat geometry also enables better surface contact with cooling systems, which can improve thermal management when properly integrated.

However, the lack of a rigid enclosure shifts structural responsibility to the surrounding system. Pouch cells require external support through module frames, compression systems, or pack-level structures to maintain dimensional stability and ensure consistent electrochemical performance.

Highest energy density potential, lightweight construction, and flexible form factor for optimized pack layouts.

Requires external mechanical support, sensitive to swelling and handling, and more demanding integration to maintain long-term performance and durability.

High energy-density systems and designs where packaging flexibility is prioritized. Examples include the Chevrolet Bolt EV and Hyundai Kona Electric

Prismatic Cells

Prismatic cells are built using stacked or folded electrodes housed in a rigid rectangular casing, typically made of aluminum or steel. This format improves space utilization and enables higher packing efficiency at the module and pack level. 

The flat surfaces enable more direct and uniform contact with cooling systems, such as cold plates or thermal interface materials, improving heat transfer and simplifying thermal management design. However, prismatic cells require careful control of mechanical tolerances and compression to accommodate expansion during cycling.

Better volumetric efficiency than cylindrical cells, cleaner packaging, and more predictable geometry for module and pack design.

More sensitive to mechanical tolerances and expansion during cycling, heavier casing compared to pouch cells, and tighter constraints on structural integration.

Automotive battery packs where packaging efficiency and structural integration are critical. Examples include the BMW i3 and Volkswagen ID.4

Battery Cell

Smallest functional unit of an EV battery where electrochemical energy storage and conversion take place. Each cell operates at a relatively low voltage (around 3–4 V), requiring many cells to be combined to meet system-level energy and power demands.

From a practical standpoint, the cell defines energy density, operating voltage window, and the fundamental thermal and safety behavior of the system.

Battery Module

Group of cells assembled into a structured unit that simplifies manufacturing and system integration. Modules connect cells in series and/or parallel to increase voltage and capacity.

They provide mechanical support and alignment while serving as an intermediate level for thermal management and electrical interconnections.

Battery Pack

Fully integrated energy storage system that combines multiple modules (or directly integrated cells) with all supporting subsystems required for operation.

This includes electrical interconnections and busbars, thermal management systems, battery management systems (BMS), and structural housing with sealing and protection features.

Cell Components & Inspection

Incoming cells and components are validated through electrical testing, sorting, and quality inspection prior to assembly.

Materials: Insulation films, surface coatings, protective layers

Why it matters: Ensures consistency, prevents latent defects, and improves pack reliability

Cell Stack Assembly

Cells are aligned and assembled into defined configurations depending on format and pack design.

Materials: Structural adhesives, spacers, alignment materials

Why it matters: Controls spacing, mechanical stability, and dimensional consistency

Module Assembly

Cells are integrated into modules with electrical interconnections and structural support.

Materials: Busbar materials (Cu, Al), dielectric coatings, structural adhesives

Why it matters: Determines electrical resistance, insulation performance, and mechanical integrity

Battery Tray & Thermal Integration

Cells or modules are installed into the tray and coupled with cooling systems for heat management.

Materials: Thermal interface materials (TIMs), gap fillers, thermal pads

Why it matters: Enables heat dissipation, reduces thermal gradients, and improves safety

Electrical Assembly & Safety Integration

High-voltage connections, BMS, and safety systems are integrated for controlled operation.

Materials: Insulation materials, potting compounds, fire barrier materials

Why it matters: Ensures electrical safety, fault protection, and thermal runaway mitigation

Enclosure Sealing & Final Assembly

The battery pack is sealed and enclosed to protect against environmental and mechanical exposure.

Materials: Sealants, gaskets, structural bonding materials

Why it matters: Prevents moisture ingress, ensures durability, and maintains enclosure integrity

Structural Materials

Structural materials are used to mechanically bond and secure components within the battery system, ensuring stability under operating conditions.

Typical materials

Structural adhesives (epoxy, polyurethane, acrylic)

What they do

Maintain alignment and structural integrity under vibration, thermal expansion, and mechanical stress.

Where they are used

Cell-to-cell Bonding

Cell-to-pack Bonding

Module-to-pack Bonding

Thermal Management Materials for Heat Transfer

Thermal interface materials (TIMs) are designed to transfer heat efficiently from cells and components to cooling systems.

Typical materials

Gap fillers (thermal gels and pads), thermally conductive adhesives, phase change materials 

What they do

They improve heat dissipation by filling air gaps and maintaining contact between surfaces.

Where they are used

 Cell-to-pack Heat Dissipation

Module-to-cold plate cooling

BMS Electronics Cooling

Thermal Management Materials for Heat Isolation

Thermal isolation materials are used to limit or slow down heat transfer between adjacent cells or components.

Typical materials

Encapsulation foams, potting compounds, thermal barriers

What they do

They help delay heat propagation during thermal events, improving system safety.

Where they are used

Cell-to-cell Protection

Module-level Protection

BMS Electronics Encapsulation & Barriers

Electrical Insulation Materials

Electrical insulation materials prevent unintended current flow within the battery system.

Typical materials

Dielectric coatings, insulating films (PET, PI), conformal coatings

What they do

They ensure electrical separation and reduce the risk of short circuits.

Where they are used

Cell-to-cell Interfaces

Busbars & Interconnects

High-voltage Electronics & BMS

Protection and Sealing Materials

Protection and sealing materials are used to shield the battery system from environmental and operational exposure.

Typical materials

Sealants (RTV silicone), gaskets, potting compounds

What they do

They protect against moisture, dust, vibration, and chemical exposure while maintaining enclosure integrity.

Where they are used

Electronics & Connectors

Pack Enclosure Sealing

BMS PCB Protection