Battery Cell Metal Defect Inspection via Thermal Resistance Change
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Solution Overview
Problem
Conventional methods for inspecting defects in the metal portions of lithium secondary batteries, such as tab disconnection and weld defects, face challenges in accuracy due to ambiguous judgment criteria and mis-inspection issues, particularly with curved weld surfaces and small resistance changes in weak welding or partial disconnections.
Innovation Solution
A method and apparatus that calculates the difference in resistance values before and after inducing heat generation in the metal portion of a battery cell, comparing these differences with a predetermined reference value to determine defects, using impedance measurement and controlled heat induction to minimize electrolyte temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If CT imaging is used for non-destructive inspection of metal portions, then inspection coverage is improved, but inspection time becomes excessively long
Solution Approach 1:
The patent changes the measurement parameter from direct resistance measurement to resistance change measurement before and after heat generation. By applying heat to the battery cell and measuring the differential resistance change, the method achieves high defect detection sensitivity without requiring time-consuming CT imaging, thus resolving the contradiction between detection accuracy and inspection time
Solution Approach 2:
The patent performs preliminary heat generation on the battery cell before the actual resistance measurement. This preliminary action of heating the cell creates a controlled thermal state that amplifies resistance changes in defective areas, enabling rapid detection without needing lengthy imaging processes, thereby reducing inspection time while maintaining high accuracy
2Productivity
If probe pin is used for weld inspection by measuring resistance, then inspection speed is improved, but mis-inspection rate increases due to curved weld surfaces
Solution Approach 1:
The patent extracts the measurement probes from direct contact with the curved weld surface. Instead of using probe pins that require physical contact with the difficult-to-reach curved surfaces, the method uses external electrodes to apply heat and measure resistance changes, eliminating the mis-inspection problem caused by poor contact while maintaining fast inspection speed
Solution Approach 2:
The patent replaces the mechanical contact-based resistance measurement system with a thermal-field-based measurement system. By using heat generation and measuring resistance changes rather than direct mechanical probe contact, the method overcomes the limitation of curved surfaces while preserving high inspection speed, resolving the contradiction between productivity and measurement precision
3Device complexity
If direct resistance measurement is used for weak welding detection, then measurement simplicity is improved, but detection accuracy deteriorates due to small resistance changes
Solution Approach 1:
The patent changes the measurement approach from absolute resistance measurement to differential resistance measurement. By measuring resistance before and after heat generation and comparing the changes, the method amplifies the subtle resistance differences caused by weak welding, achieving high detection accuracy while maintaining measurement simplicity through the use of standard measurement equipment
Solution Approach 2:
The patent applies excessive heat generation to the battery cell beyond normal operating conditions. This excessive thermal action causes significant resistance changes in defective areas, making weak welding defects detectable. The method maintains simplicity by using standard measurement equipment while the controlled excessive heating amplifies the signal for accurate defect detection
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
Provides a highly reliable inspection for defects by increasing the resistance change in defective metal portions, enabling precise detection of micro-defects like weak welding or tab disconnections through impedance changes induced by controlled heat generation.
Implementation Method 1
inducing the heat generation in the metal portion according to a heat generation condition
Implementation Method 2
calculating a difference between resistance values measured before and after inducing heat generation
Data Source
AI summary
An apparatus and method for inspecting defective battery cells according to embodiments and experimental examples of the present invention, and a system including the same, may calculate a difference between resistance values measured before and after inducing heat generation of a metal portion in the battery cell; and compare the difference with a predetermined reference value to determine whether a defect exists in the metal portion.