Battery Tab Laser Welding With Line Welds Against Separator Piercing
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Solution Overview
Problem
Lithium-ion battery electrodes and tabs welded using ultrasonic waves often form needle-shaped protrusions that can pierce the separator, leading to short circuits and safety issues due to high pressure and wear-related pseudo or over welding problems.
Innovation Solution
Employing a laser welding process to connect electrodes and tabs, creating line-shaped welding marks on an empty foil zone with a larger contact area, reducing the likelihood of piercing the separator and avoiding issues related to welding head wear and pseudo or over welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ultrasonic welding is used to connect electrodes and tabs, then welding connection is achieved, but needle-shaped welding protrusions are formed that can pierce the separator causing short circuits
Solution Approach 1:
The patent replaces the ultrasonic welding method with a laser welding method. This substitution changes the welding mechanism from mechanical ultrasonic vibration to optical laser heating, which melts and fuses the electrode and tab materials without creating needle-shaped protrusions. The laser welding process parameters (power, speed, focus) are controlled to achieve strong welding connections while maintaining smooth weld surfaces that do not pierce the separator.
Solution Approach 2:
The patent changes the welding parameters by switching from ultrasonic frequency and amplitude parameters to laser power, welding speed, and focal position parameters. This parameter transformation allows precise control over the welding process, creating welds with appropriate height and shape that provide strong electrical connection without forming harmful protrusions that could penetrate the separator.
2Strength
If ultrasonic welding is used, then welding connection is achieved, but welding head wear causes pseudo welding or over welding
Solution Approach 1:
The patent eliminates the mechanical contact between welding head and workpiece by using laser welding. The laser beam delivers energy without physical contact, so there is no wear of the welding head. This non-contact welding method ensures consistent welding quality over extended periods without the degradation issues that plague ultrasonic welding tools.
Solution Approach 2:
The laser welding system is self-maintaining in terms of the welding head (since there is no physical welding head that wears). The laser source continues to deliver consistent energy without requiring replacement or maintenance of contact components, enabling continuous production with consistent welding quality.
3Strength
If ultrasonic welding is used, then welding connection is achieved, but welding head replacement increases workload
Solution Approach 1:
By replacing the mechanical ultrasonic welding system with a laser welding system, the patent eliminates the need for physical welding head replacement. The laser optics require minimal maintenance compared to the heavy-duty ultrasonic welding horns and transducers that are subject to mechanical stress and wear, significantly reducing operational workload.
4Object-affected harmful factors
If laser welding is used to create line-shaped welding marks, then contact area with separator increases reducing piercing risk, but welding process complexity increases
Solution Approach 1:
The patent transitions from point welding or spot welding to line welding, extending the weld geometry from zero-dimensional spots to one-dimensional lines. This dimensional change increases the contact area between the weld and the separator from a point contact to a line contact, distributing the mechanical stress and eliminating the concentrated pressure that causes piercing. The line-shaped weld marks are achieved through linear motion of the laser beam or linear movement of the workpiece.
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
Prevents short circuits by reducing pressure on the separator, maintaining tab flatness, and reducing workload through elimination of welding head replacement needs, thereby enhancing battery quality and safety performance.
Implementation Method 1
an end of the tab is welded to the empty foil zone by a laser welding process
Data Source
AI summary
The present disclosure provides a battery and a portable electrical device. The battery includes a housing and a battery cell disposed in the housing; the battery cell includes electrodes and tabs, where the electrode includes a current collector and an active material layer, and the current collector includes a coating zone coated and an empty foil zone, and an end of the tab is welded to the empty foil zone by a laser welding process; a surface of the empty foil zone facing away from the tab has a plurality of welding zones arranged at intervals, and each welding zone comprises at least one line-shaped welding mark and a surface of the tab facing away from the empty foil zone has no welding mark. The protrusion of the present disclosure is less likely to pierce a separator between a positive electrode and a negative electrode.