Pouch PACK lithium battery Pack production line full analysis: core station and professional solutions

Pouch-pack lithium batteries, with their outstanding features such as high energy density, small size, excellent safety, and strong flexibility and adaptability, have become the mainstream choice in the low-speed electric vehicle market, including electric two-wheelers, electric three-wheelers, golf carts, and unmanned aerial vehicles. Dongguan Jisheng Automation, a professional supplier of Pouch-pack battery PACK production line equipment, has been deeply involved in the industry for many years. With a profound understanding and continuous innovation of new energy equipment technology, it has created an automated production line covering the entire process from "cell pretreatment - module assembly - welding -PACK assembly".

I. Overall Overview of the Production Line

The Pouch-pack lithium battery PACK production line of Dongguan Jisheng Automation, in light of the characteristics of Pouch-pack cells, adopts a modular design. Each workstation is seamlessly connected through an intelligent conveyor line and is equipped with high-precision sensors and PLC control systems to achieve automation, digitalization and traceability of the production process.
This Pouch-pack lithium battery PACK production line is precisely adapted to the production requirements of Pouch-pack lithium battery packs for low-speed electric vehicles such as electric two-wheelers (electric bicycles, electric motorcycles), unmanned aerial vehicles, electric three-wheelers, and golf carts. It can be customized and adjusted according to customers' personalized demands for battery pack capacity, size, voltage level, production rhythm, etc. Its core workstations cover a series of interlinked processes, including cell testing, sorting, cutting and flattening, cell gluing, cell stacking, TAB bending and flattening, and laser welding.

Ii. Detailed Analysis of Core Workstations

1. Battery cell sorting, cutting and leveling station: Building the first line of defense for quality

When Pouch-pack cells leave the factory, there may be individual differences in parameters such as capacity, voltage and internal resistance. If they are directly assembled, it will lead to the "barrel effect" inside the battery pack, causing some cells to deteriorate prematurely and even posing a risk of thermal runaway. Meanwhile, the tabs of pouch cells may have problems such as inconsistent lengths and uneven surfaces, which can affect the subsequent welding quality and connection reliability. Therefore, the battery cell testing, sorting, cutting and leveling station is the first key process in PACK production. Its core function is to screen qualified battery cells, ensure parameter consistency, and shape the tabs.Process principle and flow:

This work station adopts an integrated design of "testing - sorting - cutting - leveling", and the process is as follows:
⇒Battery cell feeding: Through manual or automated feeding mechanisms, Pouch-pack battery cells are batched into the silo, and the suction cups suck the battery cells into the testing station.
⇒Multi-parameter testing: After the battery cell is positioned, the test probe automatically contacts the positive and negative tabs of the battery cell to quickly detect core parameters such as the capacity, voltage, internal resistance, and self-discharge rate of the battery cell. The detection accuracy of the test equipment is as high as ±0.01V (voltage) and ±1mΩ (internal resistance), ensuring the accuracy of parameter detection.
⇒ Intelligent sorting: Based on the test data, the system classifies and sorts the battery cells according to the preset standards (such as capacity deviation ±2%, internal resistance deviation ±5%), automatically eliminating the unqualified cells (such as insufficient capacity, excessive internal resistance), and classifying the qualified cells by parameter grades to ensure that the parameters of the cells within the same battery pack are highly consistent. The sorted battery cells are sent into the corresponding material channels to achieve centralized management of "same batch, same parameters" battery cells.
⇒ TAB cutting: For cells with inconsistent TAB lengths, the cutting mechanism precisely cuts the excess parts of the tabs according to the preset dimensions to ensure that the TAB lengths of all cells are uniform, preparing for subsequent stacking and welding. The cutting accuracy reaches ±0.1mm, and the cut is smooth without burrs.
⇒TAB flattening: After cutting, the tabs may have slight bending or uneven surfaces. The flattening mechanism flattens the tabs through roller pressing or precision stamping to ensure that the surface flatness of the tabs is ≤0.05mm, thereby enhancing the adhesion and conductivity of subsequent welding.
This work station ensures the consistency and reliability of battery packs from the source through strict screening and shaping of battery cells, which is the foundation for the smooth progress of subsequent processes.

2. TAB bending and leveling station: Optimize the connection structure to enhance welding reliability

The pouch cells are manually glued one by one. After stacking, the tabs of all the cells are on the same side (or both sides), but the tabs are usually in a straight state and cannot be directly connected in series or parallel. The core function of the TAB bending and flattening station is to bend the tabs of the module at the preset Angle and shape, forming a neat connection surface for the tabs. At the same time, it flattens the bent tabs to eliminate wrinkles and deformations, ensuring the fit between the tabs and creating favorable conditions for the subsequent laser welding process.Process principle and flow：
 

The process design of this work station fully takes into account the material characteristics of the tabs (usually aluminum or copper, which have good ductility but are prone to deformation), and adopts the method of "flexible bending + precise leveling" to avoid TAB breakage or damage. The process is as follows:
⇒Module positioning: After the stacked modules are sent to the workstation, special fixtures are used to fix the modules from all sides to ensure that the modules do not shift during the bending process and the positions of the tabs are stable.
⇒ Flexible bending: The bending mechanism adopts a segmented bending design. According to the thickness and width of the tabs, it automatically adjusts the bending pressure and Angle. During the bending process, elastic pressure blocks and buffer devices are used to prevent the tabs from breaking or cracking due to excessive instantaneous force.
⇒ TAB leveling: After bending, the tabs may have slight wrinkles or uneven surfaces. The leveling mechanism uses precision rollers or presses to evenly press the connection surfaces of the tabs, ensuring that the surface flatness of the tabs is ≤0.03mm.
⇒Inspection and confirmation: The visual inspection system inspects the bent tabs to confirm whether parameters such as the bending Angle, TAB alignment, and surface flatness meet the requirements. If they are not up to standard, an automatic alarm will be triggered, and manual handling will be carried out before re-inspection.
This work station has optimized the connection structure between battery cells by bending and flattening the tabs, providing a flat and aligned connection surface for subsequent laser welding, which is a key prerequisite for ensuring welding quality.

3. Laser welding station: Achieve reliable connection and ensure electrical performance

Laser welding is the core process for achieving series and parallel connection of battery cells in the production of Pouch-pack lithium battery packs. Its principle is to use a high-energy-density laser beam to instantly melt the metal at the connection part of the tabs, fusing the tabs of multiple battery cells into one, forming a stable electrical connection. Compared with traditional resistance welding and ultrasonic welding, laser welding has the advantages of fast welding speed, narrow weld seam, small heat-affected zone, high connection strength and good electrical conductivity. It is particularly suitable for the welding of soft pack cell tabs (thin, brittle and prone to deformation).Process principle and flow：

This work station adopts fiber laser welding technology, combined with precise positioning and real-time monitoring, to ensure the stability and reliability of welding quality. The process is as follows:
⇒ Module positioning and focusing: The module with completed TAB processing is sent to the welding station. The fixture precisely fixes the module. The laser welding head automatically aligns with the TAB welding area through the visual positioning system to complete the focus calibration (with a focusing accuracy of ±0.02mm).
⇒Welding parameter Settings: Based on parameters such as the material of the TAB (aluminum, copper or composite material), thickness, and welding area, preset welding parameters such as laser power, welding speed, and pulse frequency. The equipment of Dongguan Jisheng Automation supports parameter storage and invocation, and different modules can quickly switch welding schemes.
⇒Automated welding: The laser welding head performs welding along the preset path (such as straight line, broken line, spot welding) to achieve series and parallel connection of multiple battery cell tabs. For modules with multi-row tabs, the welding heads can synchronously complete the welding of multiple rows through a multi-axis linkage mechanism, thereby enhancing production efficiency. During the welding process, the laser beam energy is concentrated, and the weld width is only 0.3-0.8mm, with a small heat-affected zone, avoiding damage to the aluminum-plastic film encapsulation of the battery cell body.
⇒Welding quality inspection: After welding is completed, the visual inspection system automatically inspects the appearance of the weld seam (such as whether there are cracks, pores, or false welds), and at the same time, it detects the conduction resistance of the welding area through the resistance testing module to ensure good conductivity and reliable connection of the welding area. Unqualified products are automatically marked and diverted to prevent them from flowing into the next process.
⇒ Module discharge: The modules that pass the inspection are sent to the subsequent processes (such as module packaging and battery pack assembly) through the conveyor line to complete the laser welding stage.
The laser welding station achieves reliable connection of the battery cell tabs through high-energy and high-precision welding processes. It is a core procedure to ensure the electrical performance of the battery pack (such as voltage, internal resistance, and stability of charge and discharge cycles), and directly determines the overall performance of the battery pack.

The performance, safety guarantee and service life of Pouch-pack lithium batteries not only depend on the quality of the battery cells themselves, but are also closely related to the degree of refinement of the PACK production process. Through standardized and intelligent station design, we achieve efficient, precise and stable assembly from individual cells to finished battery packs, providing customers with a complete one-stop solution for Pouch-pack lithium battery pack assembly that is both cost-effective and reliable.