Battery Cell Case Step Welding to Prevent Back Bead Intrusion
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Solution Overview
Problem
Existing battery cell manufacturing processes face challenges in achieving improved welding quality and efficiency, particularly in connecting multiple plates of metal material, which can lead to deformation and reduced assembly precision.
Innovation Solution
A manufacturing method involving a three-step laser welding process is employed, including one-side and other-side sub-welding operations followed by a main welding operation, with controlled heat inputs to form step welding regions and a main welding region, ensuring precise connection of plate ends while minimizing deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single welding operation is used to connect metal plates, then the manufacturing process is simple, but the welding quality is poor and deformation occurs
Solution Approach 1:
The welding process is divided into three distinct stages: first welding, second welding, and third welding. Each stage targets specific regions of the metal plate connection with controlled heat inputs, allowing progressive fusion and minimizing deformation while achieving high welding quality through staged processing rather than a single operation
Solution Approach 2:
The first and second welding operations are performed as preliminary actions to prepare the metal plate edges and create initial fusion zones before the main third welding operation. This preliminary processing reduces the complexity of the final welding by pre-positioning materials and reducing the heat input required in the concluding welding stage
2Productivity
If high heat input is used in welding, then the welding speed is fast, but back bead protrudes into the electrode assembly space
Solution Approach 1:
Different heat inputs are applied to different regions and stages of the welding process. The first and second welding operations use controlled heat inputs appropriate for their specific regions, while the third welding operation uses a different heat input level suited for the final connection, ensuring that each local area receives the optimal thermal energy without causing back bead protrusion that would compromise assembly precision
Solution Approach 2:
The heat input parameter is changed and optimized for each welding stage. By adjusting the heat input levels across the three welding operations rather than using a constant high heat input, the process achieves both high productivity through efficient welding and high manufacturing precision by preventing back bead protrusion into the electrode assembly space
3Manufacturing precision
If multiple welding operations are performed, then the welding quality is improved, but the manufacturing time increases
Solution Approach 1:
The three welding operations are merged into a single integrated manufacturing process that is performed continuously on the battery cell case. By combining multiple welding operations into one coordinated process sequence rather than separate operations, the total manufacturing time is reduced while still achieving the high welding quality that multiple passes provide
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enhances welding quality and efficiency, preventing back bead protrusion into the electrode assembly space, improving assembly precision, and reducing deformation of the battery cell case.
Implementation Method 1
performing a first welding by irradiating a laser with a first heat input to a first region
Implementation Method 2
irradiating a laser with a first heat input to a first region having a predetermined length
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
In an embodiment, a battery cell may include: a case including a first open region, a second open region facing each other, at least one step region connected to at least one of the first open region or the second open region, and a receiving region connected to the at least one step region; and an electrode assembly disposed in the receiving region, and including a positive electrode plate, a negative electrode plate, and a separator; a plurality of cap plates covering the first open region and the second open region; at least one step welding region formed in the at least one step region; and a main welding region connected to the at least one step welding region and formed in the receiving region. The receiving region has a first thickness greater than a second thickness of the at least one step region.