Laser-Welded Battery Tabs With Dot Weld Marks Against Separator Piercing
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Solution Overview
Problem
Lithium-ion batteries face safety issues due to needle-shaped welding protrusions formed during ultrasonic welding, which can pierce the separator between electrodes, causing short circuits and safety problems.
Innovation Solution
Laser welding is used to connect the electrodes and tabs, forming dot-shaped welding marks with a concave and annular convex part, reducing the likelihood of piercing the separator and maintaining the original flatness of the tab surface, thus preventing short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ultrasonic welding is used to connect the electrode and tab, then the welding connection is achieved, but needle-shaped welding protrusions are formed that may pierce the separator causing short circuits
Solution Approach 1:
The patent replaces the ultrasonic welding method (mechanical vibration-based) with laser welding method (optical energy-based). The laser welding process melts and fuses the electrode and tab materials without generating needle-shaped protrusions, thereby eliminating the separator piercing risk while maintaining strong welding connection. This substitution of welding mechanism fundamentally resolves the contradiction between connection strength and safety.
Solution Approach 2:
The patent changes the welding process parameters by switching from ultrasonic vibration parameters to laser energy parameters (wavelength, power, pulse duration). This parameter transformation allows the welding process to achieve strong bonding without forming harmful protrusions, as the laser heating and melting mechanism produces a different weld morphology compared to ultrasonic welding.
2Object-affected harmful factors
If laser welding is used to connect the electrode and tab, then needle-shaped protrusions are avoided and separator piercing is prevented, but the welding process must be precisely controlled to avoid over-welding or pseudo-welding
Solution Approach 1:
The patent implements feedback control in the laser welding process by monitoring welding parameters (power, speed, pulse frequency) and adjusting them in real-time based on weld quality detection. This feedback mechanism ensures precise control of the laser welding process, preventing both under-welding (pseudo-welding) and over-welding, thereby maintaining high manufacturing precision while eliminating separator piercing risks.
3Strength
If the tab surface is welded to ensure strong connection, then the welding strength is improved, but the tab surface flatness is compromised forming unfavorable structures
Solution Approach 1:
The patent applies local quality principle by concentrating the laser welding action only on the specific welding zone where the electrode and tab overlap, rather than welding the entire tab surface. This localized welding approach ensures strong connection at the joint interface while preserving the flatness of the tab's external surface, eliminating unfavorable structures that could affect separator positioning.
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
The solution effectively prevents short circuits by reducing pressure on the separator and maintaining the tab's flatness, enhancing the quality and safety performance of lithium-ion batteries.
Implementation Method 1
an end of the tab overlaps the empty foil zone and the tab and the empty foil zone are fixedly connected by laser welding
Implementation Method 2
a welding head is in contact with a tab side and applies pressure and vibrations to weld and connect the tab and the electrode
Data Source
AI summary
The present disclosure provides a battery, a manufacturing method thereof and an electronic product. The battery cell includes electrodes and tabs, where each of the electrodes includes a current collector and an active material layer, and the current collector includes a coating zone coated with the active material layer and an empty foil zone, and an end of a tab overlaps the empty foil zone and the tab and the empty foil zone are connected by laser welding; the side of the empty foil zone facing away from the tab has a plurality of dot-shaped welding marks arranged at intervals, and the dot-shaped welding marks include a concave part and an annular convex part surrounding the concave part. The contact area between the annular convex part and the separator between the positive electrode and the negative electrode is large, and the separator is less likely to be pierced.