The different lithium-ion cell shapes offered by SIG Energy Technology

There are three types of Lithium-ion cells on the market: prismatic, cylindrical and pouch cells. Each one has its own interest of use according to its final application. Pocket cells have the particularity of resembling small ultra-thin bags. While they are known to be used for portable battery applications, cylindrical and prismatic cells are more integrated in industrial and automotive applications.

This article is an introduction to the cells on which SIG Energy Technology is focusing its research, innovation and production efforts: cylindrical cells and prismatic cells.

I. Activities and strategic positioning

SIG Energy Technology targets the industrial and automotive markets. Since 2015, it has positioned itself at the same level of quality and performance as the dominant groups known on the market. It took 3 years of intensive testing before SIG Energy Technology was able to provide high quality solutions to an ambitious and demanding clientele.

II. Cells in cylindrical and prismatic format

The final application, the mechanical and electronic objectives as well as the spatial constraints are all elements to consider when defining the cell format to be integrated into the project.

• Cylindrical cells, as their name indicates, have a cylinder shape, such as the usual AAA batteries for example. You will find in our catalog the models 18650 (diameter 18mm, height 650 mm), 21700 (diameter 21mm, height 700 mm) and 26650 (diameter 26mm, height 650 mm). Larger sizes are currently being studied, such as the 4680 cells. SIG Energy Technology has decided to complete its range of #NMC cells with three new references in #LFP (18650, 26650 and 21700), which is rare on the cylindrical market and allows to combine the advantages of chemistry and format.
  Advantages: quick voltage rise, power devices in small spaces (portable devices, scooters, bikes...)
  Disadvantages: they require soldering points to be connected together and therefore special devices for integration as well as a risk of defects in manufacturing.
• Prismatic cells, rectangular in shape, are larger than cylindrical cells and contain more energy. There are many models, of varying height and width, although standards are tending to develop, particularly for the automotive industry (VDA/MEB) or cell-to-pack.
  Advantages: fewer units to connect, therefore easier to install, simplified integration by using busbars and screws, possibility of replacing only one cell
  Disadvantages: the numerous dimensions of existing cells can make a module difficult to replace in the event of a production stoppage of a reference, format unsuitable for very small applications, deformation during life problem solved thanks to our spacers.
  Prismatic cells are especially known for their fast energy rise, while cylindrical cells are distinguished by their power.

III. Energy / Power of the cell

For both cylindrical and prismatic cells, the design will develop more power or energy. The "Power" cells will be dedicated to automotive projects while the "Energy" cells will be dedicated to stationary projects.

• The power cells support high currents (>1C), making possible fast charging or strong discharge peaks. They are therefore suitable for high-performance electric vehicles, despite the impact on cell ageing in these "extreme" conditions. The challenge for power batteries is temperature management, which can go from 25°C to 80°C in a few minutes. SIG Energy Technology initially selected high performance products and then approached partners for integration and thermal management for specific projects.
• The energy cells offer lower C-rates in charge and discharge (<=1C), however the number of cycles will significantly increase. They are therefore particularly used in stationary storage projects, and in the service of renewable energies.

IV. What to remember

SIG Energy Technology, attentive to the singularity of its customers' projects, offers cylindrical and prismatic cells, of power and energy, in the formats and chemistries of its expertise (LFP/NMC). Thus, you will be able to obtain from SIG Energy Technology the cell adapted to your needs, without ever neglecting the qualitative criteria (characterization of the capacity at different C-Rate, internal resistance, SOC-OCV, cyclic ageing), and safety (IEC62619 or equivalent, UN38.3 for transport, presence of pressure valve, CID or PTC).

Our sales and R&D teams will answer all your questions on request and provide you with the best solution for your project.