Battery Terminal Weld Junction Integrity Evaluation
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Solution Overview
Problem
The process capability of ultrasonic welding in battery cell weld junctions is subject to variation due to ultrasonic welder variations and other factors, affecting the integrity of the welds within the sealed pouch of battery cells.
Innovation Solution
A test fixture is used to evaluate the integrity of battery cell weld junctions by applying a dynamic vibrational excitation load and a static load, allowing for non-destructive assessment of the welds' integrity through a stress test routine that includes clamping the cell body, gripping the terminals, and monitoring displacement during the application of loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ultrasonic welding process is used to join electrode foils and terminals, then manufacturing efficiency is improved, but weld junction integrity becomes subject to variation
Solution Approach 1:
The patent applies preliminary action by performing a stress test on the weld junction before the battery cell is considered complete. The test fixture applies dynamic and static loads to the terminal before final assembly, identifying potential weld defects early in the manufacturing process rather than after assembly, thereby ensuring reliability while maintaining productivity
Solution Approach 2:
The patent implements feedback by using sensors to monitor the response of the weld junction during stress testing. The system measures displacement, force, and vibration characteristics during dynamic and static loading, providing real-time feedback on weld quality. This feedback mechanism allows for immediate identification of defective welds and adjustment of manufacturing parameters
2Adaptability or versatility
If ultrasonic welder variations are present, then manufacturing flexibility is improved, but manufacturing precision deteriorates
Solution Approach 1:
The patent applies parameter changes by systematically varying test parameters such as dynamic load frequency, static load magnitude, and vibration amplitude to characterize weld junction behavior. By changing these parameters during testing, the system can identify optimal ranges that ensure consistent weld quality despite variations in ultrasonic welding parameters, thereby maintaining manufacturing precision while allowing flexibility in the welding process
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 reliable evaluation of weld junction integrity, identifying and rejecting battery cells with compromised welds, thereby ensuring consistent quality and preventing potential electrical short circuits.
Implementation Method 1
A dynamic stress end effector coupled to the terminal gripper applies a vibrational excitation load to the terminal
Implementation Method 2
The positive charge portions of the electrode foils are ultrasonically welded together and welded to the positive terminal, and the negative charge portions of the electrode foils are ultrasonically welded together and welded to the negative terminal
Data Source
AI summary
A method and a test fixture for evaluating a battery cell composed of a cell body having a plurality of electrode foils, a positive terminal and a negative terminal, wherein the positive terminal and the negative terminal are each joined to the cell body at weld junctions. This includes retaining the cell body of the battery cell in a first clamping device. The terminal is grasped in a terminal gripper. A dynamic stress end effector coupled to the terminal gripper applies a vibrational excitation load to the terminal. A static stress end effector applies a static load to the terminal. Integrity of the weld junction is evaluated based upon the applied static load.