Metal Drawing

With the development of new energy vehicles and energy storage systems, the requirements for the structural safety and process precision of lithium batteries are increasing. The aluminum alloy stretch shell is the main protective structure of square lithium batteries. Its material selection and processing technology are directly related to the performance, safety, and life performance of lithium batteries. Among many materials, 3003-H14 aluminum alloy has become the mainstream material for Lithium Battery Aluminum Cases due to its excellent processing performance and corrosion resistance.

3003-H14 aluminum alloy is an aluminum-manganese alloy with the following characteristics:

1. Good formability: The H14 state means that the material has been processed in a semi-hard state, with certain strength and ductility, and is suitable for the multi-pass aluminum alloy stretching process.

2. Strong corrosion resistance: The addition of manganese elements improves the corrosion resistance and adapts to the electrolyte environment of lithium batteries.

3. Balance between strength and lightweight: The tensile strength is between 145-195MPa, which is higher than pure aluminum for Lithium-ion Battery Aluminum Shell, and the density is low (2.73g/cm³), which meets the weight reduction needs of the new energy industry.
4. Excellent welding performance: convenient for subsequent laser welding and sealing of the Power Battery Cover Plate.

The main technical parameters are as follows:

Since lithium battery cells generate heat during charging and discharging, good thermal conductivity is particularly critical for shell materials. The 3003-H14 aluminum alloy not only has good thermal diffusion ability but also can resist electrolyte corrosion in long-term service, ensuring the sealing and structural integrity of the Battery Aluminum Housing.

Aluminum alloy stretching is a typical metal sheet forming process, which relies on a special stretching die to perform multiple continuous stamping, stretching, and shaping of aluminum alloy strips or discs, and finally forms an Aluminum Battery Case structure with a certain height, depth, and precision.

In the production of lithium battery shells, our factory adopts a progressive design of 9 continuous stretching dies. Through automatic feeding and in-mold conversion, the aluminum alloy discs are deformed from the initial sheet to the finished shell after 9 processes.

Technical difficulties in mold design include:

1. Stretching uniformity control: Multi-pass molds need to ensure that the material is evenly distributed and deformed during the stretching process to avoid tearing or wrinkling of the material.

2. Mold wear resistance design: Aluminum alloy is relatively soft, and the mold material must have high hardness and good polishing properties to maintain the mold life and product surface quality.
3. Guidance and positioning accuracy: Each level of the mold must maintain strict position alignment to ensure the coordination and consistency between the mold and the Aluminum Alloy Prismatic Battery Case during continuous stamping.
4. Lubrication and cooling system: Continuous stretching has high requirements for mold friction, and the lubrication oil circuit design and heat dissipation efficiency directly affect mold stability and product accuracy.

The reasonable design of the stretching die is the key factor in determining the quality and consistency of the LiFePO4 Aluminum Case Battery Cell.

Our factory is equipped with 10 new energy Aluminum Laminate Pouches for Li-ion Batteries' automatic production lines, with a daily production capacity of 100,000 aluminum alloy shells. These production lines realize the full process automation from automatic feeding-continuous stretching-trimming-cleaning-inspection-packaging.

Brief description of the main process:

1. Automatic feeding system: The aluminum alloy disc is accurately positioned in the mold through a robotic arm, improving efficiency and accuracy.
2. Continuous stamping and stretching: 9 stretching dies are used to continuously stamp the aluminum sheet to form a square shell structure.
3. Trimming and shaping: The edges of the shell are trimmed to standardize the size, which facilitates subsequent assembly.
4. Ultrasonic degreasing and cleaning: Ultrasonic cleaning technology is used to remove residual stamping grease to ensure product cleanliness.
5. Online detection: Through machine vision and dimensional measurement systems, the wall thickness, size, and appearance quality of each Aluminum deep drawing stamping battery case are monitored in real time.
6. Automatic stacking and packaging: Automatic material collection and packaging equipment are used to achieve standardized batch shipments.

This highly automated production method not only improves production efficiency but also significantly improves the consistency and quality control level of lithium battery aluminum alloy stamping shells

In lithium battery systems, the Aluminum shell for Prismatic and cylindrical battery cases not only plays a physical protective role but also directly relates to the thermal management performance, structural stability, and bursting strength of battery cells. Therefore, it is particularly important to precisely control the wall thickness all around during the stretching process. Insufficient wall thickness of Lithium Batteries Square Aluminum Shell may cause bulging or cracking of battery cells during charge and discharge expansion; while excessive wall thickness increases weight, reduces energy density, and affects overall performance. Therefore, achieving high-precision wall thickness control is the core link to ensure the performance and safety of lithium battery systems.

1. Bursting force and pressure resistance
Excessive deviation of shell wall thickness will lead to insufficient local strength and easy rupture when the battery is thermal away. The wall thickness tolerance of the 3003-H14 shell needs to be controlled at ≤±0.05mm and the bursting pressure needs to be ≥1.2MPa (national standard requirement).

Precision stretching can ensure the consistency of thickness of four corners and side walls to avoid the risk of shell bursting due to stress concentration.

2. Sealing and welding quality
The insufficient flatness of the shell opening will affect the sealing of the cover plate welding and cause electrolyte leakage. The mold design needs to reserve a shaping station to ensure the dimensional accuracy of the opening end.

3. Battery energy density
A shell that is too thick increases weight and reduces energy density; a shell that is too thin affects structural strength. The work-hardening characteristics of 3003-H14 need to balance the material thinning rate through mold design.

The lithium battery aluminum alloy stretched shell produced by our factory is widely used in the following fields:

1. New energy vehicle battery pack: Square aluminum shell battery cells are the mainstream power battery structure and are widely used by OEMs such as BYD and CATL.

2. Energy storage system battery module: It is used in scenarios such as home energy storage, industrial energy storage, and backup power supply for communication base stations, and has excellent structural strength and corrosion resistance.

3. Smart devices and mobile power supplies: Some high-end mobile power supplies also use aluminum alloy square shells to improve product grade and heat dissipation efficiency.

In the future, as lithium batteries develop towards higher energy density and higher safety standards, higher requirements will be placed on the precision and performance of the Prismatic Cell Aluminum Battery Case. Stretching die technology, material modification, and surface treatment processes will become the key directions for continuous optimization. As the core of new energy technology, the structural parts process of lithium batteries is an important guarantee for safety and performance. The use of 3003-H14 aluminum alloy combined with advanced aluminum alloy stretching die design and automated stamping process not only achieves high-efficiency and high-consistency mass production but also provides a solid foundation for the development of new energy vehicles and energy storage industries.