Battery Cell Diagnosis Using EIS Reactance Slope
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods fail to effectively detect lithium precipitation in battery cells during the production process, which can lead to battery ignition issues, making it difficult to diagnose defective cells.
Innovation Solution
A method and apparatus using electrochemical impedance spectroscopy (EIS) measurements with an activation waveform to calculate the reactance slope of battery cells, distinguishing between normal and defective cells based on the slope within a predetermined voltage range, employing a charger/discharger, EIS meter, and processor to diagnose lithium precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional diagnosis methods are used, then the production process is simple, but lithium precipitation cannot be detected
Solution Approach 1:
The patent performs EIS measurement during the activation process (charging section) before the battery is put into service. By conducting the diagnosis in advance during manufacturing, lithium precipitation can be detected early without requiring complex post-production testing equipment.
Solution Approach 2:
The patent changes the measurement parameters by using EIS with specific frequency ranges (1-25 Hz) and analyzing reactance slope in a specific voltage section (3.5V-3.8V). This parameter-specific approach enables precise detection of lithium precipitation while using standard equipment.
2Measurement precision
If EIS measurement is performed during activation process, then lithium precipitation can be detected, but measurement time increases
Solution Approach 1:
The EIS measurement is integrated into the activation process (charging section) that must be performed anyway before battery delivery. This preliminary action approach allows detection of lithium precipitation without adding separate testing time to the production schedule.
Solution Approach 2:
The patent performs EIS measurement in a specific voltage section (3.5V-3.8V) rather than the entire charging range. This partial measurement approach focuses on the critical region where lithium precipitation indicators are most apparent, reducing overall measurement time while maintaining detection accuracy.
3Measurement precision
If reactance slope analysis is used, then diagnosis accuracy improves, but calculation complexity increases
Solution Approach 1:
The patent transforms the raw EIS data into a meaningful diagnostic parameter by calculating the reactance slope in the voltage section of 3.5V-3.8V. This parameter transformation simplifies the diagnosis by converting complex impedance spectra into a single slope value that directly indicates lithium precipitation status.
Solution Approach 2:
The system uses the calculated reactance slope as feedback to automatically diagnose whether lithium precipitation has occurred. The processor compares the slope value against predetermined thresholds and provides immediate diagnostic results, creating a closed-loop system that improves accuracy without requiring manual analysis.
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 accurate diagnosis of defective cells with lithium precipitation by differentiating reactance slopes, allowing for early detection and prevention of battery failures.
Implementation Method 1
performing an electrochemical impedance spectroscopy (EIS) measurement in a charging section of the activation process
Implementation Method 2
a lithium battery which uses lithium ions in a redox reaction
Data Source
AI summary
Discussed are a method and an apparatus for diagnosing a battery cell. The method may include applying, by the apparatus for diagnosing the battery cell, an activation waveform having a predetermined frequency to the battery cell in an activation process, and performing an electrochemical impedance spectroscopy (EIS) measurement in a charging section of the activation process. The method may further include, based on the EIS measurement, calculating a slope of a reactance of the battery cell in a voltage section of a predetermined range, and diagnosing the battery cell based on the slope.