SHINHOP laser

Lithium batteries are widely used in industries such as digital appliances, power tools, and energy storage systems due to their high energy density, high voltage, environmental friendliness, long lifespan, simple recycling, and fast charging capabilities. Especially in recent years, the development of new energy vehicles has seen unprecedented contributions. With the emergence of traditional energy crises and various environmental issues, the development of new energy has become an imperative project. Batteries, especially power battery technology products used in the automotive industry, have enormous development potential and are one of the important strategies encouraged and supported by national policies.
Next, let SHINHOP Laser Group take you to learn about the basics of PACK battery packs!
1. Classification of PACK battery packs
1. What is PACK (battery pack), and what are its components and types?
There are many types of battery packs. From the perspective of the types of cells that make up the PACK battery pack, there are cylindrical battery PACKs, soft pack battery PACKs, and square aluminum shell battery PACKs. However, from the perspective of its components, a battery PACK is composed of battery cells (commonly known as cell), battery modules, and finally becomes a battery pack.
Battery cell: It is the basic unit that makes up the battery module. Generally, the voltage of a single cell is between 3-4V, with 3.7V being common.
Battery module: A battery module is composed of several cells. The purpose is to limit any issues in the entire battery PACK to a specific module, without affecting the quality and safety of other modules.
Battery PACK: Composed of battery modules, it also includes cooling systems, protection systems, etc., which become finished products like power batteries that can be directly supplied to users.

Classification of PACK components

Battery pack (PACK) integrated with chassis
As mentioned above, the three major types of cells have different characteristics. For example, soft pack batteries have many specifications, can be customized in size and shape, are lightweight, and are mostly used in digital appliances, with some already applied in power battery PACKs. Cylindrical batteries are generally made as 18650 cylindrical cells, with fewer models and common industry specifications. Besides the above models, there are also 32650/26650/22650/17650, etc. However, regardless of the manufacturer, these are the few models, unlike soft packs, which may have some special sizes and shapes. Cylindrical batteries are also an important component of power batteries, such as those used in Tesla cars. Finally, square large aluminum shell cells were applied in power batteries earlier, currently have a high market share, are safer, easy to weld and produce, and have a larger capacity.

Left - Cylindrical winding, Middle - Square winding, Right - Square stacking

Left - Cylindrical cell, Middle - Square shell cell, Right - Soft pack cell
2. How is the battery module constructed?
The battery module mentioned above is composed of cells, connected in different series and parallel through busbars (soft connection pieces), and is made of various materials, which can be nickel sheets, copper, copper-plated nickel, aluminum-plated nickel, etc. Different materials may use different connection methods. For example, if it is a copper sheet, it is generally fastened with screws; for nickel sheets, traditional methods include resistance welding, ultrasonic welding, wire welding, laser welding, etc. Currently, the most reliable and widely used method is laser welding, due to its high efficiency and good yield. It not only does not increase the resistance of the connection points but also makes the welds more secure, and has been widely applied in major battery manufacturers, significantly enhancing the market competitiveness of battery PACK products.

Left - Cylindrical module, Middle - Square shell module, Right - Soft pack module
3. Battery PACK (battery pack)

Left - Cylindrical PACK, Right - Square PACK

Soft pack PACK diagram
4. What is the composition of the PACK battery pack?
It mainly includes several parts: battery module, mechanical system, electrical system, thermal management system, and BMS.
Battery module:
The core of PACK is the battery module, but without support from other parts, it cannot function. If we compare PACK to a person, then the battery module is the heart, responsible for energy storage and output.
Mechanical system:
It provides various supports for the battery module, preventing external mechanical shocks, vibrations, and other environmental impacts. It facilitates the establishment and packaging of the battery module, much like a human skeleton!
Electrical system:
It mainly consists of high-voltage busbars or high-voltage harnesses, low-voltage harnesses, and relays. The high-voltage harness can be seen as the "main artery" of the battery PACK, continuously delivering power from the heart of the power battery system to various required components, while the low-voltage harness can be seen as the "nervous system" of the battery PACK, transmitting detection signals and control signals in real-time.
Thermal management system:
The thermal management system mainly has four types: air cooling, water cooling, liquid cooling, and phase change materials. Taking the water cooling system as an example, the thermal management system mainly consists of cooling plates, cooling water pipes, thermal insulation pads, and thermal conductive pads. The thermal management system is like an air conditioning system for the battery PACK.
BMS:
Battery management system, can be seen as the "brain" of the battery. It mainly consists of CMU and BMU.
CMU: Cell monitor unit, responsible for measuring parameters such as voltage, current, and temperature of the battery, and also has balancing functions. When the CMU measures these data, it transmits the data to the BMU through the aforementioned "nervous system" of the battery.
BMU: Battery management unit.
Responsible for evaluating the data transmitted by CMU. If the data is abnormal, it will protect the battery by issuing a request to reduce the current or cut off the charge and discharge path to prevent the battery from exceeding permissible usage conditions. It also manages the battery's power and temperature. Based on the previously designed control strategy, it determines the parameters and states that need to be alerted and sends the alerts to the vehicle controller, which is ultimately communicated to the driver.

PACK battery pack explosion diagram
5. Process Flow
The battery PACK is the core energy source of new energy vehicles, providing driving power for the entire vehicle. As a core component of new energy vehicles, its quality directly determines the performance of the entire vehicle. Lithium battery manufacturing equipment generally consists of front-end equipment, mid-stage equipment, and back-end equipment, and the precision and automation level of these devices will directly affect the production efficiency and consistency of the products.
Although the types of cells and modules are different, the composition and process flow of the PACK are generally the same (not all manufacturers have the same process flow), as shown in the figure below for reference.
Figure --- PACK assembly process flow
Mainly divided into assembly process, airtightness testing process, software writing process, electrical performance testing process, etc.
II. Production Line Introduction
There are many flexible circuits and pressing and tightening in the PACK assembly process, making automation difficult and the input-output ratio not high. Therefore, the degree of automation of back-end equipment is relatively low compared to front-end and mid-stage equipment, but it can accommodate three types of PACK battery packaging: cylindrical, square shell, and soft pack.
Possible automated workstations required:
1. Automatic online lower shell
2. Automatic online module into the shell
3. Module fixed tightening
4. Upper cover online and tightening
5. Automatic application of A/B thermal conductive adhesive (depending on the process)
6. Automatic application of sealing adhesive (depending on the process)
7. Finished product offline
Additionally, some may require automatic methods for copper plate installation and screw tightening, airtightness testing, and EOL testing, which are relatively rare and have stability challenges.
There are mainly two types of operation modes for back-end PACK line mass production equipment:
1. AGV + assembly trolley: Previously used more in car factories, now battery factories are gradually promoting this model.

AGV conveyor method production line

AGV production line logistics simulation
2. Conveyor line + pallet mode: roller line/friction roller line/multiplication chain conveyor line

Conveyor line method production line

Left - multiplication chain, right - friction roller line
Summary
The above is a basic explanation of lithium battery pack PACK.
With the in-depth development of the power battery industry, battery technology will become more mature and advanced, especially in high-speed charging, large-capacity storage, and battery safety technology, which will see better development and can quickly promote the development of the new energy vehicle industry. Its technology involves many disciplines and requires a lot of engineering applications for practical verification. Therefore, if car companies want to ensure stable and reliable quality and a good safety level for power battery PACK, and enhance the competitiveness of their products in the market, they need to work hard on basic research to better innovate and optimize battery products.
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