Lithium Battery Welding Process and Quality Control

Lithium batteries require the use of various laser welding processes during the manufacturing process. Each of these processes has its unique functions and importance. By selecting and using these laser welding processes appropriately, the quality and performance of the battery can be ensured to meet the requirements of different application scenarios. The welding processes involved in the manufacturing of lithium batteries include cap laser welding, tab laser welding, end face laser welding, copper foil laser welding, busbar laser welding, and welding of flexible connections. In the following example, we will introduce the process flow and quality inspection procedures for tab laser welding in lithium battery manufacturing.

1.Tab Welding Process for Lithium Batteries

1.1 Preparation:

a. Check the dimensions and quality of the tab, battery cell, and welding materials.

b. Prepare the welding equipment, such as spot welding machine or ultrasonic welding machine.

c. Ensure that the welding environment meets the requirements, including temperature, humidity, cleanliness, etc.

1.2 Tab Cutting and Tab Bending:

a. Cut the tab to the appropriate length based on the size of the battery cell.

b. Use specialized tools to bend the tab into the desired shape for connection with the battery cell.

1.3 Tab-to-Cell Connection:

a. Align the bent tab with the tab hole on the battery cell.

b. Use a spot welding machine or ultrasonic welding machine to weld the tab and the battery cell together.

1.4 Welding Quality Inspection:

a. Check for any signs of incomplete welding, weak welding, or poor bonding at the welding area.

b. Verify that the connection between the tab and battery cell is secure and free from any loosening.

c. Perform strength testing on the welding area to ensure the welding quality.

1.5 Cleaning and Packaging:

a. Clean any residues or oxides from the welded area to ensure the tab surface is clean.

b. Package the welded battery cells to protect them from damage during transportation and storage.

The tab welding process for lithium batteries requires strict adherence to operating procedures to ensure welding quality, improve battery performance, and enhance safety.

2．Parameter Settings

The parameter settings for lithium battery tab welding need to be determined based on the specific welding equipment and materials, but generally include the following aspects:

2.1 Welding Current: Set the welding current based on the thickness of the welding material and the power of the welding equipment. In general, higher welding currents result in deeper penetration, but excessive current can cause electrode overheating and affect welding quality.

2.2 Welding Time: The welding time refers to the duration of contact between the electrode and the welding material. Generally, longer welding times result in higher welding strength, but excessively long welding times can cause electrode overheating and affect welding quality.

2.3 Welding Pressure: Welding pressure refers to the pressure applied by the electrode on the welding material. Generally, higher welding pressure results in greater welding strength, but excessive pressure can cause electrode deformation and affect welding quality.

2.4 Welding Speed: Welding speed refers to the speed at which the electrode moves. Generally, faster welding speeds result in higher welding efficiency, but excessively fast speeds can result in insufficient contact time between the electrode and the welding material, affecting welding quality.

2.5 Welding Electrode: Select suitable welding electrodes based on the welding material and welding equipment. In general, the material, shape, and size of the welding electrode can affect welding quality and efficiency.

When performing tab welding for lithium batteries, these parameters need to be adjusted according to the specific conditions to ensure welding quality, improve welding efficiency, and ensure safety.

3.Welding Precautions

During the welding process for lithium battery tab connections, it is important to pay attention to the following points:

3.1 Ensure that the tab and battery cell dimensions and quality meet the requirements.

3.2 Select appropriate welding equipment and welding parameters.

3.3 Ensure that the welding environment meets the specified conditions.

3.4 Ensure a secure and tight connection between the tab and the battery cell during welding.

3.5 Perform stringent quality inspections on the welds.

3.6 Exercise caution when cleaning the welded area.

3.7 Properly protect the surface of the battery cell during packaging.

Failure to adhere to proper procedures or neglecting the above points may result in reduced welding quality, decreased battery performance, and potential safety hazards. Therefore, it is crucial to strictly follow operating guidelines and pay attention to the mentioned considerations.

4.Quality Control for Welding

Quality inspection for lithium battery tab welding is a critical step in ensuring welding quality, improving battery performance, and ensuring safety. It generally includes several aspects such as visual inspection, strength testing, electrical performance testing, leak testing, and durability testing. When performing quality inspections, it is important to select appropriate inspection methods and standards based on specific circumstances and ensure accurate and reliable inspection results. If welding quality issues are identified, prompt measures should be taken to address them and ensure battery performance and safety. The specific aspects are as follows:

4.1 Visual Inspection: Check for issues such as incomplete welds, weak welds, or any signs of loose connections between the tab and the battery cell.

4.2 Strength Testing: Perform strength tests on the welded areas, such as tension tests or pressure tests, to ensure welding quality.

4.3 Electrical Performance Testing: Conduct electrical performance tests on the welded areas, such as insulation resistance tests or current tests, to ensure welding quality.

4.4 Leak Testing: Perform leak tests on the welded areas, such as helium leak detection or bubble tests, to ensure welding quality.

4.5 Durability Testing: Conduct durability tests on the welded areas, such as temperature cycling tests or humidity cycling tests, to ensure welding quality.

When performing quality inspections for lithium battery tab welding, it is important to select appropriate inspection methods and standards based on specific circumstances and ensure accurate and reliable inspection results. If welding quality issues are identified, prompt measures should be taken to address them and ensure battery performance and safety.

5.Summary

The process of lithium battery tab welding involves several steps, including preparation, tab cutting and bending, tab-to-cell connection, welding quality inspection, and cleaning and packaging. When performing tab welding, it is important to ensure that the tab and battery cell dimensions and quality meet the requirements, select appropriate welding equipment and parameters, ensure the welding environment meets the specifications, ensure a secure connection between the tab and the battery cell, conduct rigorous welding quality inspections, handle cleaning of the welded area with care, and properly package the battery cells. It is crucial to strictly follow operating guidelines and pay attention to the mentioned considerations to ensure welding quality, improve battery performance, and ensure safety.