Insulation Failure Inspection Using Impulse Voltage Waveforms
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Solution Overview
Problem
Conventional methods for inspecting insulation failures in lithium ion batteries are inaccurate and often result in non-defective cells being rejected, while defective cells cannot be reused due to high voltage testing, which can cause new insulation breakdowns.
Innovation Solution
An insulation failure inspection method using an impulse voltage applied between the metal terminal and metal foil layer, with waveform measurement to detect capacitance changes, allowing for accurate detection of existing and potential short circuits without causing further damage, and enabling reuse of inspected cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high voltage is applied for insulation failure inspection, then detection capability is improved, but new insulation breakdown occurs causing cells to be rejected
Solution Approach 1:
The patent applies periodic impulse voltage instead of continuous high voltage. The inspection uses repeated short-duration voltage pulses (e.g., 1ms to 100ms duration) at controlled intervals, allowing detection of insulation failures through capacitance changes while giving the insulation layer time to recover and preventing new breakdowns in marginal cases.
Solution Approach 2:
The patent dynamically adjusts inspection parameters including voltage magnitude, pulse duration, and frequency based on the specific cell being inspected. The system adapts the impulse characteristics to balance detection sensitivity with cell safety, rather than using fixed high voltage thresholds.
2Measurement precision
If conventional inspection methods are used, then defective cells can be identified, but false positives occur causing non-defective cells to be rejected
Solution Approach 1:
The patent employs feedback mechanisms where the capacitance response to impulse voltage is analyzed to determine insulation status. The system compares measured capacitance values against reference ranges and adjusts subsequent inspection parameters based on previous measurements, reducing false positives by confirming defects through multiple measurement cycles rather than single-threshold decisions.
3Measurement precision
If high voltage testing is performed, then insulation failures are detected, but the heat-sealable resin layer melts causing new short circuits
Solution Approach 1:
The patent uses very short-duration impulse voltage pulses (microsecond to millisecond range) that deliver sufficient voltage for detection but complete before thermal energy can accumulate and melt the heat-sealable resin layer. The inspection rushes through the critical voltage application phase so quickly that harmful thermal effects are avoided.
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 method increases inspection accuracy, prevents new insulation breakdowns, and allows for the reuse of electrochemical cells by using a low voltage impulse to avoid melting the heat-sealable resin layer, thereby reducing false positives and cell damage.
Implementation Method 1
an impulse voltage is applied between the metal terminal and the metal foil layer, and a waveform of a voltage applied to a capacitance between the metal terminal and the metal foil layer is measured
Data Source
Figure 1A~1D
Figure 2~3
Figure 4
AI summary
Disclosed is a method for manufacturing an electrochemical cell, wherein an insulation failure product can be accurately rejected, and an electrochemical cell can be used again after the insulation failure inspection. In the method for manufacturing the electrochemical cell (1), which is configured by hermetically housing an electrochemical cell main body (20) such that the leading end of a metal terminal (21) protrudes to the outside of the outer housing (10), an impulse voltage is applied between the metal terminal (21) and a metal foil layer (12), the waveform of the voltage applied to the capacitance between the metal terminal (21) and the metal foil layer (12) is measured, and the insulation failure inspection step is performed.