Laser Welding Electrode Tab Joining Process
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Solution Overview
Problem
Existing methods for joining electrode stacks in lithium-ion batteries, such as ultrasonic welding, pose a high risk of particle formation leading to short circuits and lack stability and homogeneity in electrical resistance.
Innovation Solution
A multi-stage joining process using laser welding, where anode and cathode tabs of partial stacks are sequentially joined with their respective current collectors, with additional separators between stacks, allowing for high mechanical stability and homogeneous electrical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ultrasonic welding is used to join electrode tabs, then joining speed and productivity are improved, but particle formation occurs leading to short circuits and reduced reliability
Solution Approach 1:
The patent replaces ultrasonic welding (mechanical/vibrational system) with laser welding (optical/thermal system). The laser beam melts and fuses the electrode tabs without mechanical contact, eliminating particle generation while maintaining high joining speed. This substitution resolves the contradiction by achieving both high productivity and reliability through a fundamentally different physical mechanism.
2Productivity
If ultrasonic welding is used to join electrode tabs, then joining efficiency is improved, but connection homogeneity and electrical resistance uniformity deteriorate
Solution Approach 1:
The patent changes the physical parameters of the joining process by using laser welding instead of ultrasonic welding. The laser parameters (power, speed, focus position) can be precisely controlled to achieve uniform melting and fusion across all electrode tabs, ensuring homogeneous connections and consistent electrical resistance while maintaining high joining efficiency.
3Reliability
If multi-stage joining process is implemented, then connection reliability and homogeneity are improved, but process complexity increases
Solution Approach 1:
The patent combines the stacking process with the joining process into a single integrated operation. As each new electrode stack is placed on the stack, the laser immediately welds the electrode tabs to the current collectors without requiring separate joining steps. This merging reduces process complexity while maintaining the reliability benefits of controlled, sequential joining.
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 prevents particle formation that can cause short circuits, enhances process stability, and allows for online control, providing a cost-effective solution by integrating joining into the stacking process without time loss, suitable for various applications including electric vehicles and consumer electronics.
Implementation Method 1
A multi-stage joining process using laser welding, where anode and cathode tabs of partial stacks are sequentially joined with their respective current collectors
Data Source
Figure 1a~1b
Figure 1c
Figure 2a~2b
AI summary
The invention refers to a method for joining an electrode stack (100) of several partial stacks (2), whereat a partial stack (2) comprises an anode (4) with an anode tab (6), a cathode (8) with a cathode tab (10) and at least one separator (12) arranged between the anode (4) and the cathode (8), and whereat at least one further separator (12) is arranged between the partial stacks (2). The several partial stacks (2) are placed on top of each other in a stacking process, and the anode tabs (6) of the several partial stacks (2) are joint to each other and with an anode current collector in a multi-stage joining process, and the cathode tabs (10) of the several partial stacks (2) are joint to each other and with a cathode current collector in a multi-stage joining process. The invention also refers to a battery cell comprising an electrode stack (100) produced by the method according to the invention.