Battery Tab Laser Welding Through Transparent Pressing Material
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Solution Overview
Problem
Existing methods of laser welding electrode tabs to current collecting units in secondary batteries often result in voids (welding failure portions), which increase battery resistance.
Innovation Solution
The method involves sandwiching the electrode tab between a transparent material and the current collecting unit and applying laser to penetrate the transparent material, ensuring the electrode tab is stacked without gaps, using a pressure of 100 N or more, and employing a transparent material with a melting point of 800°C or more, such as crystallized glass, quartz glass, barium fluoride glass, or sapphire glass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If laser welding is performed by stacking electrode tabs on current collecting unit without additional components, then the welding process is simple, but voids are generated in the welded zone increasing battery resistance
Solution Approach 1:
A transparent material is introduced as an intermediary component between the laser source and the electrode tab/current collector assembly. This transparent material serves multiple functions: it transmits laser energy to enable welding, provides pressure application surface for gap elimination, and maintains structural integrity during the welding process. The intermediary resolves the contradiction by enabling reliable welding without requiring complex positioning or clamping mechanisms.
2Reliability
If pressure is applied to eliminate gaps between electrode tabs and current collecting unit, then voids are reduced in welded zone, but additional pressing mechanism increases device complexity
Solution Approach 1:
The transparent material combines multiple functions into a single component: it serves as both the laser transmission medium and the pressure application surface. By merging these functions, the invention eliminates the need for separate pressing mechanisms while achieving gap elimination and void reduction in the welded zone.
3Reliability
If transparent material with high melting point is used to withstand laser heat, then welding reliability improves, but material selection becomes more restricted
Solution Approach 1:
The invention specifies a melting point parameter threshold (800°C or higher) for the transparent material to ensure it can withstand laser welding temperatures without deforming. This parameter-based approach provides clear selection criteria while maintaining welding reliability. Common materials meeting this criterion include sapphire, quartz glass, and certain ceramics, which are well-established in industrial applications.
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 approach significantly reduces voids in the welded zone, thereby minimizing battery resistance and ensuring stable welding between the electrode tab and the current collecting unit.
Implementation Method 1
welding between the electrode tab and the current collecting unit by sandwiching the electrode tab between a transparent material and the current collecting unit and then applying laser to penetrate the transparent material
Implementation Method 2
applying laser to penetrate the transparent material
Data Source
Figure 1
Figure 2
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AI summary
Provided is a technique to reduce voids between an electrode tab (21t, 22t) and a current collecting unit (33, 43) in a portion where the electrode tab (21t, 22t) and the current collecting unit (33, 43) are welded. The manufacturing method disclosed herein is a method of manufacturing a secondary battery (100) including an electrode body (20) having an electrode tab (21t, 22t) and a current collecting unit (33, 43) electrically connected to the electrode body (20). This method includes: welding between the electrode tab (21t, 22t) and the current collecting unit (33, 43), by sandwiching the electrode tab (21t, 22t) between a laser transparent material (G) and the current collecting unit (33, 43) and then applying laser (LA) to penetrate the transparent material (G) and welding the tabs and the current collector unit. This method avoir projection of spatters.