Secondary Battery Multi-Tab Laser Welding With Optical Defect Inspection
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Solution Overview
Problem
Ultrasonic welding methods for secondary batteries lack reliable quality verification, making it difficult to detect welding defects such as weak bonding, as existing inspection methods rely solely on appearance and do not ensure total quality verification.
Innovation Solution
Implementing a laser welding method and monitoring system that includes a perforated defect inspection device and a back bead inspection device to automatically determine welding defects by analyzing light transmission and reflection images, ensuring thorough quality inspection of welded portions on thin-film bases and multi-tabs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ultrasonic welding is used to bond multi-tab to base tab, then welding process is simple and fast, but welding quality cannot be reliably verified and bonding strength is insufficient
Solution Approach 1:
The patent replaces ultrasonic welding (mechanical vibration-based) with laser welding (optical energy-based). The laser welding process uses a laser beam to melt and join the multi-tab to the base tab, enabling both high productivity and reliable quality verification through automated optical inspection systems that can detect welding defects and measure bond strength.
Solution Approach 2:
The patent introduces an automated inspection system as an intermediary between the welding process and quality assessment. This system includes cameras and sensors that capture images of the welded portion, automatically analyze welding quality, and provide feedback on bonding strength, thereby enabling reliable verification without compromising welding speed.
2Productivity
If appearance inspection only is performed on welded portion, then inspection process is simple and fast, but welding defects such as weak bonding cannot be detected
Solution Approach 1:
The patent replaces manual appearance inspection with an automated optical inspection system. The system uses cameras to capture images of the welded portion and automatically analyzes them to detect welding defects, weak bonding, and other quality issues, thereby maintaining high inspection speed while significantly improving detection accuracy.
Solution Approach 2:
The patent creates optical copies (images) of the welded portion using cameras and image processing systems. These digital copies allow for automated analysis and detection of welding defects without requiring physical contact or slowing down the production process, thus maintaining high inspection speed while improving precision.
3Strength
If laser welding is used to join multi-tab with electrode bases, then bonding strength and welding reliability are improved, but device complexity and inspection system cost increase
Solution Approach 1:
The patent designs the inspection system to perform multiple functions: capturing images of the welded portion, analyzing welding quality, detecting defects, and measuring bond strength. This multi-functional approach consolidates what could be multiple separate inspection devices into a single integrated system, reducing overall complexity while maintaining high bonding strength through laser welding.
Solution Approach 2:
The inspection system is designed to automatically analyze welding quality and detect defects without requiring manual intervention. The system self-calibrates and self-evaluates welding parameters, reducing the need for complex external monitoring equipment and simplifying the overall device complexity while ensuring high bonding strength through consistent quality control.
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 laser welding method provides higher bonding strength and reliability, with improved quality distribution and reduced standard deviation of tensile forces, while the monitoring system automates defect detection, enhancing working efficiency and reducing human error.
Implementation Method 1
a welded portion in which the multi-tab is welded with the positive electrode base and the negative electrode base is melting-joined by using a laser
Implementation Method 2
a backlight configured to irradiate the welded portion with light in a direction from a first surface toward a second surface opposite the first surface of the welded portion
Implementation Method 3
a front light configured to irradiate the welded portion with light in a direction from the second surface toward the first surface of the welded portion
Data Source
AI summary
Embodiments relate to laser welding methods, monitoring methods, and monitoring systems for a secondary battery. A laser welding method for a secondary battery includes performing laser welding on a positive electrode base having a thin-film shape in which a plurality of positive electrode base tabs are formed at a side, a negative electrode base having a thin-film shape in which a plurality of negative electrode base tabs are formed at a side, and a thin-film multi-tab to be joined to each of the positive electrode base and the negative electrode base, a welded portion in which the multi-tab is welded with the positive electrode base and the negative electrode base being melting-joined by using a laser such that a plurality of welding spots is formed on the welded portion.