Battery Electrode Tab Disconnection Detection Using Impedance Spectra
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Solution Overview
Problem
Existing methods for detecting electrode tab disconnections in battery cells are inadequate for mass production due to the need for pressurization mechanisms and lengthy inspection times, and they struggle to accurately differentiate between normal and tab-disconnected battery cells based on impedance measurements.
Innovation Solution
An electrode tab disconnection inspection apparatus using a K-nearest neighbor (K-NN) algorithm compares impedance values of a battery cell with a predetermined data group to determine disconnections by selecting nearest neighbor data points, allowing for accurate classification of battery cells as normal or tab-disconnected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressurization mechanism is used to measure impedance change, then disconnection detection capability is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent extracts the pressurization function from the inspection system, eliminating the need for external pressurization mechanisms. Instead, the battery cell's own internal pressure variations during charging/discharging are utilized to induce impedance changes that reveal disconnection defects, thereby simplifying the inspection apparatus while maintaining detection capability
Solution Approach 2:
The battery cell itself serves as the pressure source through its normal charging and discharging operations. The internal pressure changes that occur naturally during electrochemical reactions are harnessed to generate the impedance variations needed for disconnection detection, eliminating the need for external pressurization equipment
2Measurement precision
If CT scanning is used for physical inspection, then disconnection detection capability is improved, but inspection time increases
Solution Approach 1:
The patent replaces the mechanical/optical CT scanning system with an electrical measurement system. By measuring impedance changes in the frequency domain during normal battery operation, the system achieves disconnection detection without the time-consuming mechanical scanning process, reducing inspection time to seconds
Solution Approach 2:
The inspection is performed using impedance measurements taken during routine charging/discharging operations before the battery is put into service. This preliminary electrical characterization allows rapid identification of disconnection defects without requiring separate inspection time, as the measurement occurs during normal operational cycles
3Productivity
If impedance value comparison method is used, then inspection speed is improved, but measurement precision deteriorates due to overlapping impedance regions
Solution Approach 1:
The patent transitions from comparing single impedance value points to analyzing impedance characteristics across the entire frequency domain. By examining the spectral distribution and patterns of impedance across multiple frequencies, the system can distinguish between normal and defective cells even when their impedance magnitudes overlap, thereby maintaining high inspection speed while improving determination accuracy
Solution Approach 2:
The patent transforms the impedance data from simple magnitude values into frequency-domain spectral patterns, analogous to changing from grayscale to color information. This spectral fingerprinting approach provides additional discriminatory features that enable accurate classification of battery cells based on their unique impedance signatures across different frequencies
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
The apparatus enables quick and accurate detection of electrode tab disconnections, facilitating efficient manufacturing and recycling processes by reducing false positives and negatives in disconnection determination.
Implementation Method 1
an impedance measurement part connected to electrode leads of a battery cell to be inspected, and configured to measure an impedance value according to a frequency of the battery cell
Data Source
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AI summary
An electrode tab disconnection inspection apparatus of a battery cell according to the present technology includes: a measurement part configured to measure impedance values and impedance angles according to a frequency of a battery cell to be inspected; an arithmetic part configured to calculate real part resistance values of impedance according to the frequency of the battery cell to be inspected from the impedance values and the impedance angles; and a determination part configured to compare real part resistance values of a real part resistance value region in a resonant frequency range of non-defective battery cells of the same type as the battery cell to be inspected and real part resistance values of impedance of the battery cell to be inspected in a frequency range having the same range as the resonant frequency range to inspect whether electrode tabs of the battery cell to be inspected are disconnected.