Laser Welded Battery Lead Joint With Controlled Melting Width
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Solution Overview
Problem
Welding a lead to a sealing plate in sealed batteries often results in sputtered substances causing internal short-circuits due to gaps or foreign substances, leading to reduced joint strength and potential thermal runaway.
Innovation Solution
A method where the lead is laser-welded to the sealing plate with a continuously scanned laser beam having a spot diameter smaller than the lead's thickness, ensuring a smaller melting width at the end section compared to the center section, and applying negative pressure to remove sputtered substances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If resistance welding is used to join the lead to the sealing plate, then joint strength is improved, but sputtered substances are generated causing internal short-circuits
Solution Approach 1:
The patent replaces resistance welding (mechanical/electrical system) with laser welding (optical system). The laser beam melts and fuses the lead to the sealing plate without generating sputtered substances, thus eliminating internal short-circuits while maintaining joint strength.
Solution Approach 2:
The patent changes the welding parameters by using a laser beam with spot diameter smaller than the lead thickness, creating a keyhole effect that confines melting to a narrow region. This parameter change prevents sputtering while achieving strong joint between lead and sealing plate.
2Object-generated harmful factors
If laser welding with spot diameter smaller than lead thickness is used, then sputtered substances are reduced, but manufacturing precision is required to maintain melting width control
Solution Approach 1:
The patent employs periodic scanning of the laser beam across the lead width, moving the laser spot in a controlled manner to create a consistent melting pattern. This periodic action ensures uniform melting width and prevents excessive melting at edges while minimizing sputtering.
Solution Approach 2:
The patent uses continuous laser beam scanning without interruption to maintain steady-state melting conditions. This continuity ensures consistent energy input and melting width control throughout the welding process, preventing variations that could lead to sputtering or poor joint quality.
3Productivity
If the laser beam is continuously scanned, then productivity is improved, but the melting width must be precisely controlled to prevent holes in the lead
Solution Approach 1:
The patent implements feedback control by monitoring the welding process parameters (laser power, scanning speed, focal position) and adjusting them in real-time to maintain optimal melting width. This feedback mechanism allows high-speed continuous scanning while preventing hole formation in the lead.
Solution Approach 2:
The patent dynamically adjusts the laser scanning parameters during the welding process, varying the scanning speed and laser power based on the position and material conditions. This dynamic control enables high productivity through continuous scanning while maintaining precise melting width control to prevent defects.
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 approach significantly reduces the formation of holes in the lead, minimizes sputtered substances, and maintains high joint strength, preventing abnormal heat generation from internal short-circuits.
Implementation Method 1
a lead extending from one of the electrode plates (1, 2) in the electrode group (4) is laser-welded to the sealing plate (10)
Implementation Method 2
laser-welding the other end of the lead (11) to the sealing plate (10) by continuously scanning a laser beam (12)
Implementation Method 3
substances (mainly metal particles removed from a welded portion of the lead) can be sputtered
Data Source
AI summary
A sealed battery including: an electrode group 4 formed by winding or stacking a positive electrode plate 1 and a negative electrode plate 2 with a separator 3 interposed between the positive electrode plate 1 and the negative electrode plate 2, and housed in a battery case 5, an opening of the battery case 5 being sealed with a sealing plate, wherein a lead 11 extending from one of the electrode plates in the electrode group 4 is laser-welded to the sealing plate 10, and a melting width of an end section 13 of a welded portion 9 between the lead 11 and the sealing plate 10 is smaller than a melting width of a center section of the welded portion 9.