Angled Battery Tab Welding for Porosity-Free Terminal Joints
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Solution Overview
Problem
Existing methods for welding external tabs of electrodes to internal terminals in battery cells often result in porous welds and detachments due to the lap joint configuration, particularly when using foil current collectors, leading to quality issues in battery cell connections.
Innovation Solution
The method involves laser welding external tabs of anode and cathode electrodes to internal terminals at a predetermined angle, with optional gas relief channels and clamping to ensure secure connections, eliminating the need for ultrasonic welding and enhancing weld quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If lap joint configuration is used for welding external tabs to internal terminals, then welding process is simple, but weld quality deteriorates with porous welds and detachments
Solution Approach 1:
The patent changes the welding configuration from a conventional lap joint (where tabs are welded parallel to the terminal surface) to an asymmetric angled joint. The external tabs are welded at an angle of 10° to 80° relative to the terminal surface, creating a more robust joint geometry that eliminates porous welds and detachments while maintaining manufacturing feasibility through adjusted welding parameters.
2Reliability
If ultrasonic welding is used for joining tabs to terminals, then connection is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent replaces the ultrasonic welding process (which requires complex ultrasonic generation equipment, transducers, and control systems) with a conventional laser welding or resistance welding process. By changing the joint configuration to an angled joint, the simpler thermal or resistive welding methods achieve comparable or superior connection reliability without the need for ultrasonic manufacturing equipment.
3Ease of operation
If external tabs are welded parallel to terminal surface, then welding alignment is easy, but weld strength decreases due to porous welds
Solution Approach 1:
The patent introduces an asymmetric angle (10° to 80°) between the external tabs and the terminal surface during welding. This angled configuration improves weld strength by eliminating the porous weld defects characteristic of parallel lap joints, while the alignment process remains straightforward by simply positioning the tabs at the specified angle relative to the terminal surface.
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 improves the quality and reliability of welds between external tabs and internal terminals, reducing detachments and ensuring robust connections in battery cells, applicable to various form factors like pouch and prismatic cells.
Implementation Method 1
laser welding ends of the external tabs to the one of an inner surface and an outer surface of the first portion of the terminal
Data Source
AI summary
A method for manufacturing a battery cell includes providing a stack including C cathode electrodes each including a cathode current collector, a cathode active layer, and an external tab extending from the cathode current collector, A anode electrodes including an anode current collector, an anode active layer, and an external tab extending from the anode current collector, and S separators. The method includes providing a terminal including a first portion connected to a second portion at a predetermined angle less than or equal to 100°; positioning external tabs of one of the A anode electrodes and the C cathode electrodes in contact with one of an inner surface and an outer surface of the first portion of the terminal; and laser welding ends of the external tabs to the one of an inner surface and an outer surface of the first portion of the terminal.