Battery Tab Laser Weld Rows for Strength With Less Spatter
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Solution Overview
Problem
Existing methods for welding a battery current collector foil and tab lead, such as ultrasonic and laser welding, face challenges in achieving high welding strength and low current density while minimizing the weld area, particularly with metals like copper, leading to issues like spatter scattering and increased electrical resistance.
Innovation Solution
A laser processing method using blue or green laser light to weld the current collector foil and tab lead, arranging welds in multiple linear rows perpendicular or parallel to the tab lead direction, optimizing the ridgeline length and reducing the weld area to ensure both high welding strength and low current density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If IR laser welding is used to join current collector foil and tab lead, then welding strength can be maintained, but spatter scattering occurs significantly due to low absorption rate of laser light by metals like copper
Solution Approach 1:
The patent changes the wavelength parameter of the laser from IR (around 1000 nm) to blue (450-480 nm) or green (500-560 nm). This parameter change increases the absorption rate of laser light by copper and other metals, thereby reducing spatter scattering while maintaining welding strength. The absorption rate of copper for blue laser is approximately 60-70% compared to only 10-20% for IR laser.
Solution Approach 2:
The patent substitutes the IR laser system with a blue or green laser system. This substitution fundamentally changes the interaction mechanism between laser light and metal, replacing the low-absorption IR mechanism with a high-absorption visible light mechanism, thereby eliminating the spatter problem while maintaining the welding function.
2Strength
If weld area is increased to ensure high welding strength, then joint strength is improved, but electrical resistance increases due to larger current density in the weld region
Solution Approach 1:
The patent uses blue or green laser with higher absorption rates to achieve the same welding strength with a smaller weld area. The higher energy coupling efficiency allows concentrated welding in a smaller region, thereby reducing the area through which current must pass and lowering electrical resistance.
3Reliability
If weld area is minimized to reduce electrical resistance, then current density is improved, but welding strength may be compromised
Solution Approach 1:
The patent changes the laser wavelength parameter to blue or green range, which increases the absorption rate by copper and aluminum materials. This allows achieving sufficient welding strength in a smaller area, thereby maintaining both high current density performance and adequate welding strength.
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 method achieves efficient welding with reduced spatter and metal powder scattering, ensuring smooth current flow and low electrical resistance by enhancing welding strength and minimizing the weld region, thus improving energy efficiency.
Implementation Method 1
metals, especially when a target is a metal such as copper... have a low absorption rate of laser light
Implementation Method 2
radiating laser light selected from a blue laser and a green laser... laser welding is performed by radiating laser light
Implementation Method 3
laser welding... performing a process of performing tack welding... and a process of performing main welding
Data Source
AI summary
Provided is a laser processing method capable of ensuring both high welding strength and low current density while suppressing the area of a weld region at the time of welding a current collector foil and a tab lead of a battery. The laser processing method includes a step of laser welding a current collector foil 2 and a tab lead 3 at an end of a battery, wherein the laser welding is performed by radiating laser light selected from a blue laser and a green laser. When a direction in which the tab lead extends from the end of the battery is defined as a first direction, the laser welding is performed such that welds are arranged in a plurality of linear rows perpendicular to the first direction.