Battery Weld Inspection Using Impedance and Cole-Cole Analysis
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Solution Overview
Problem
Conventional methods for inspecting the welding state of battery electrodes are destructive and time-consuming, leading to inefficiencies and potential battery damage.
Innovation Solution
A non-destructive method involving impedance measurement and Cole-Cole plot analysis is employed to determine the welding state of battery electrodes by measuring impedance before and after electrolyte injection, using AC current or voltage in specific frequency bands and analyzing x-intercept and minimum values on Cole-Cole plots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a destructive inspection method of manually sampling welding regions is used, then the welding state can be inspected, but it causes lots on hold and reduces productivity
Solution Approach 1:
The patent replaces the mechanical destructive sampling method with an electrical impedance measurement system. By applying AC voltage and measuring impedance characteristics (Cole-Cole plots) across different frequencies, the system non-destructively detects welding quality without physical contact or damage to the battery components, thereby maintaining productivity while ensuring inspection accuracy.
Solution Approach 2:
The patent introduces impedance measurement as an intermediary method between direct physical inspection and final quality determination. The Cole-Cole plot analysis serves as a mediator that translates electrical impedance data into welding quality assessment, enabling indirect but accurate evaluation of welding states without destructive sampling.
2Measurement precision
If manual sampling inspection is performed, then welding quality can be assessed, but it requires time-consuming processes and cannot perform in-line total inspection
Solution Approach 1:
The patent implements continuous impedance measurement across multiple frequency points to generate complete Cole-Cole plots for every battery unit. This continuous measurement approach replaces discrete manual sampling, enabling in-line total inspection where every battery is assessed without interruption or time loss, while maintaining comprehensive welding quality evaluation through the full impedance spectrum.
Solution Approach 2:
The patent varies the AC voltage frequency parameter across a spectrum (e.g., 10 Hz to 10 kHz) to generate comprehensive impedance data. By changing this single parameter systematically, the system obtains complete Cole-Cole plots that fully characterize welding quality, replacing the need for multiple manual inspection steps and significantly reducing inspection time.
3Productivity
If impedance measurement is performed before electrolyte injection, then welding state can be determined non-destructively, but the measurement must be completed before a critical process step
Solution Approach 1:
The patent performs impedance measurement and welding quality assessment as a preliminary action before electrolyte injection. By completing the inspection at this early stage in the manufacturing process, the system enables rapid non-destructive evaluation without interfering with subsequent critical steps, allowing defective batteries to be identified and removed before they undergo additional processing.
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
Enables rapid, in-line inspection of battery welding quality, allowing for the identification and removal of defective batteries, improving production efficiency and quality without damaging the batteries.
Implementation Method 1
measuring a first impedance by applying an AC current or an AC voltage in a set frequency band
Implementation Method 2
creating a first Cole-Cole plot based on the first impedance; determining the welding state of the battery based on an x-intercept value on the first Cole-Cole plot
Data Source
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AI summary
The present invention provides a method for inspecting the state of welds in a battery, the state of welds being inspected for a battery having: a tap or current collection plate welded to a current collector of an electrode assembly in which the current collector and separation film have been wound or stacked; and a can housing or electrode lead welded to the tap or current collector plate. The method comprises: a first impedance measurement step for measuring first impedance by applying, prior to injecting electrolyte into a battery, alternating current or alternating voltage at a set frequency band; a first Cole-Cole plot preparation step for preparing a first Cole-Cole plot on the basis of the first impedance; and a primary state of welds determination step for determining the state of welds of the battery on the basis of x fractional value on the first Cole-Cole plot.