Laser End-Face Welding of Metallic Foils for Low-Stress Battery Tabs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for welding metallic foils in Li-ion battery production, such as resistance welding, ultrasonic welding, and laser welding, face limitations in the number of layers that can be stacked and subject thin electrode foils to excessive thermal and mechanical stress, especially as the number of electrodes increases.
Innovation Solution
A method involving a parallel joint arrangement where metallic foils are welded by directing a laser beam onto the end face of the foils, reducing the energy input required and minimizing stress by creating a less-deep and longer weld seam, allowing for a large connection cross-section without needing to weld through the entire stack thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser welding is performed through the entire stack thickness to ensure bond to collector, then welding reliability is improved, but thermal stress and mechanical stress on thin electrode foils increase excessively
Solution Approach 1:
The invention extracts the welding action from the conventional broad-side approach and redirects it to the end face of the parallel joint. By taking out the welding process from the traditional configuration and applying it to the end face, the laser beam welds through a significantly reduced thickness (only the thickness of the parallel joint rather than the entire stack), thereby maintaining bonding reliability while dramatically reducing thermal stress and mechanical stress on the thin electrode foils.
2Quantity of substance
If the number of electrode foils is increased to enhance energy storage capacity, then energy density is improved, but the complexity and difficulty of welding increases
Solution Approach 1:
The invention changes the welding dimension from broad-side (through the entire stack thickness) to end-face (through the parallel joint thickness only). This dimensional change allows multiple thin foils to be welded simultaneously without increasing welding complexity, as the laser beam applies energy to the end face where all foils converge, creating a parallel joint that bonds all layers at once rather than requiring sequential welding through each layer.
3Use of energy by moving object
If energy input per unit length is increased to weld through thicker stacks, then welding penetration is improved, but damage to thin electrode foils increases
Solution Approach 1:
The invention extracts the welding action from the conventional broad-side approach and redirects it to the end face of the parallel joint. By taking out the welding process from the traditional configuration and applying it to the end face, the laser beam welds through a significantly reduced thickness (only the thickness of the parallel joint rather than the entire stack), thereby maintaining bonding reliability while dramatically reducing thermal stress and mechanical stress on the thin electrode foils.
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
This method enables the welding of a large number of foils with reduced mechanical and thermal stress, maintaining the integrity of thin foils and preventing tear formation, while allowing for efficient current conduction without the need to weld through the entire stack, thus enhancing energy storage capacity.
Implementation Method 1
welding the metallic foils together by directing a laser beam onto an end face of the parallel joint of the foils, such that a weld seam joining the foils is formed
Data Source
AI summary
A method for welding metallic foils includes the method steps of: forming a parallel joint with a plurality of metallic foils to be joined, by arranging the foils in such a way that they contact each other over a wide area, and welding the metallic foils together by directing a laser beam onto an end face of the parallel joint of the foils, such that a welded seam joining the foils is formed.