Battery Cell Impedance Sorting via Frequency Sweep
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Solution Overview
Problem
Existing methods for measuring the internal impedance of rechargeable batteries are time-consuming and not suitable for rapid assessment, especially when dealing with large numbers of cell modules or individual cells.
Innovation Solution
A method and apparatus that determine the internal impedance of rechargeable battery cells by generating impedance curves across a predefined frequency range, allowing for the sorting of cells into quality classes based on their impedance characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional capacity measurement methods are used to measure battery cells, then measurement accuracy is improved, but measurement time increases significantly
Solution Approach 1:
The patent replaces traditional mechanical/electrical capacity measurement methods with electrochemical impedance spectroscopy (EIS). Instead of measuring actual charge-discharge capacity over time, the system uses impedance measurements at multiple frequencies to characterize battery cells. This substitution of measurement methodology dramatically reduces measurement time while maintaining sufficient discrimination capability for cell sorting.
Solution Approach 2:
The patent changes the measurement parameter from direct capacity measurement to impedance measurement across multiple frequencies. By measuring impedance at several frequency points (e.g., 0.1 Hz, 1 Hz, 10 Hz, 100 Hz) and analyzing the resulting impedance spectrum, the system can differentiate between good and degraded cells without performing time-consuming capacity tests. This parameter transformation enables rapid assessment.
2Reliability
If comprehensive battery cell testing is performed to ensure quality, then reliability is improved, but productivity decreases
Solution Approach 1:
The patent applies partial action by measuring impedance at a selected set of frequency points rather than performing exhaustive testing across the entire frequency spectrum. The method uses a practical subset of frequencies (e.g., 4-5 specific frequency points) that provides sufficient information for quality assessment without the time cost of complete spectral analysis. This partial measurement approach maintains reliability while enabling high throughput.
Solution Approach 2:
The patent performs preliminary impedance characterization to identify cells that clearly meet or fail quality criteria before more extensive analysis. By using initial impedance measurements at multiple frequencies to quickly screen cells and identify obvious outliers, the system can rapidly sort large batches of cells with high confidence, improving overall productivity while maintaining quality assurance.
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 reliable and efficient measurement of internal impedance, facilitating the sorting and reuse of battery cells, thereby improving battery management and extending battery life.
Implementation Method 1
determining a respective impedance curve for a plurality of cells extracted from a plurality of rechargeable batteries, wherein each impedance curve is descriptive of an internal impedance of the respective cell as a function of frequency over a predefined frequency range
Data Source
AI summary
According to an example embodiment, a method is provided, the method comprising: determining a respective impedance curve for a plurality of cells extracted from a plurality of rechargeable batteries, wherein each impedance curve is descriptive of an internal impedance of the respective cell as a function of frequency over a predefined frequency range; determining, for each of the plurality of cells, respective one or more impedance characteristics based on the impedance curve determined for the respective cell; and sorting the plurality of cells into one or more quality classes in accordance with the one or more impedance characteristics determined for the plurality of cells.