Battery cell, Battery Module or Pack. What’s the difference?

Battery modules and packs are not the same; they represent different stages in battery applications and have distinct differences

What are the Common battery cell types?

Pouch Cell: These batteries have high energy density, can be customized in size, have mature manufacturing processes, low cost, but relatively lower safety compared to other types. They are suitable for small factories and laboratories. Pouch Cells are primarily used in consumer electronics, and even some large-scale power battery manufacturers use Pouch Cell. Pouch Cells are also used in energy storage applications.

Cylindrical Battery: It has relatively low energy density and relatively low capacity (although the situation has improved with the emergence of larger cylindrical batteries). The battery is not suitable for high-rate discharge. It is the most mature battery in terms of manufacturing processes, resulting in relatively low manufacturing costs. It has higher safety performance compared to pouch batteries. The size is fixed, which facilitates large-scale production and coordination with upstream and downstream manufacturers. There is a trend of gradual replacement in the field of power batteries.

NPP LiFePO4 Battery Cylindrical Cell

Prismatic Battery: It has relatively good safety performance and allows for more flexible size variations compared to cylindrical batteries, although not as much as pouch batteries. It can be used to make high-capacity batteries and is suitable for battery grouping. The manufacturing process is relatively simple, making it suitable for large-scale production. Large prismatic batteries, with individual battery energy exceeding 1 kilowatt-hour, have already been widely used. Additionally, the use of prismatic batteries, similar to blade-type batteries, is increasing. These batteries can omit the battery module assembly step, facilitating battery grouping. Moreover, with increased battery surface area and reduced thickness, heat dissipation is improved, thus enhancing the safety performance of the batteries.

Battery Module

What is Battery module?

The basic components of a battery module include module control, battery cells, conductive connectors, plastic frames, cooling plates, cooling tubes, end plates, and a set of fasteners that assemble these components together. In addition to collecting the individual cells and providing a certain amount of pressure, the end plates are often designed to secure the module’s structure within the assembly.

A lithium battery module is composed of several to hundreds of battery cells connected in parallel and series. In addition to the structural design, when combined with a battery management system and thermal runaway control management system, it forms a relatively complete lithium battery pack system.

Generally speaking, regardless of whether it is a pouch cell, Prismatic Battery, cylindrical battery, or 18650 battery, the automated assembly process of the module starts with the battery cell feeding. The incoming materials can be in the form of packaging provided by the original supplier or specially arranged trays prepared by the manufacturer after inspection. The feeding process can be done manually or automated through a conveyor belt, followed by the use of robotic arms for grabbing. During the feeding process, the battery cells are also subjected to code reading (collecting individual cell’s identity data), polarity detection (checking for reverse polarity), cell sorting and grouping, and removal of defective products.

After the incoming materials have undergone initial inspection and sorting, they will be processed differently based on the module and process requirements. These processes may include laser cleaning, adhesive coating, cell stacking, battery box assembly, tab cutting and shaping, module shell laser welding, module laser marking, screwing, module testing, tab laser welding, BMS system connection, module final testing, and module cutting, among others.

The module has both structural and functional requirements for the materials used, which include flame-retardant polymers such as PP, PA, PC, PC/ABS, etc. Depending on the connection method between the cells and the conductive busbars, the module can be processed in three forms: welding, screwing, and mechanical press-fit, involving processes such as laser welding.

Battery Module

What is Battery PACK?

PACK stands for packaging, assembly, and integration. The process includes processing, assembly, and packaging. The PACK production line generally only needs to perform two functions: transportation and testing. Currently, most manufacturers use semi-automatic PACK assembly lines, mainly for the assembly, testing, in-house transportation, and packaging of PACKs. For example, when two batteries are connected in series and assembled into a specific shape according to customer requirements, we refer to it as a pack:

In the PACK industry, the individual cells that are not assembled into a usable battery are often referred to as battery cells, while the finished battery with connections to the PCM board and functionalities such as charging and discharging control is called a battery.

The PACK system serves the battery cells and requires consistency and high reliability. By utilizing highly automated advanced intelligent equipment, control is exercised at each manufacturing stage to ensure the consistency of the battery.

The “cell-module-battery pack” is a hierarchical structure from micro to macro, where the cells need to be precise, the modules assembled from cells ensure safety, and the battery pack composed of modules is also safe.

The “battery pack-module-cell” is a hierarchical structure from macro to micro, where if the battery pack casing is damaged, the module casing can still provide protection; and if the module casing is damaged, the cell itself has self-protection capabilities.

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