Battery Degradation Assessment Using Equivalent Circuit Constants
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Solution Overview
Problem
Existing methods for secondary battery degradation determination, such as JP 2022-020404, require full charging and discharging to acquire charging and discharging characteristics, making them inefficient for recycling companies to assess battery reuseability.
Innovation Solution
A battery degradation determination system using a processor to measure and calculate equivalent circuit constants based on charging and discharging characteristics, allowing for quick and efficient degradation assessment by comparing initial and post-use constants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full charging and discharging is performed to acquire charging and discharging characteristics, then degradation determination accuracy is improved, but determination time increases significantly
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing equivalent circuit constants (R0, R1, C1) during battery manufacturing or initial charging. These pre-calculated constants serve as reference values for later degradation comparisons, eliminating the need to perform full charge-discharge cycles at the time of degradation assessment. The recycling company can directly compare measured constants against these pre-stored references to determine degradation status.
Solution Approach 2:
The patent extracts the essential degradation indicators by focusing only on measuring terminal voltage and current during a simple constant current charge, then calculating equivalent circuit constants from these measurements. This extracted approach isolates the key parameters (R0, R1, C1) that indicate degradation, removing the need for complete charge-discharge characteristic acquisition while maintaining determination accuracy.
2Loss of information
If traditional charging and discharging characteristic measurement is used, then comprehensive battery performance data is obtained, but the process becomes complex and time-consuming
Solution Approach 1:
The patent extracts only the essential information needed for degradation determination by measuring terminal voltage and current during a simplified constant current charge process. From these extracted measurements, equivalent circuit constants are calculated to represent battery performance, eliminating the need for complex multi-stage charge-discharge protocols while retaining the critical degradation indicators.
Solution Approach 2:
The patent changes the measurement parameters from comprehensive charge-discharge characteristics to specific equivalent circuit constants (R0, R1, C1) that can be derived from simplified measurements. This parameter transformation converts a complex measurement problem into a simpler one where degradation is indicated by changes in these specific electrical parameters rather than requiring full performance curves.
Data Source
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AI summary
A battery degradation determination system includes a battery degradation determination apparatus (10) configured to perform degradation determination for a secondary battery (20). The battery degradation determination apparatus (10) includes a processor. The processor is configured to measure a charging and discharging characteristic value of the secondary battery (20); to calculate a first equivalent circuit constant in an equivalent circuit in which a power supply is a main tank circuit including a first resistive element and a first capacitive element that are connected in parallel, based on the measured charging and discharging characteristic value; and to perform the degradation determination for the secondary battery (20), based on at least the first equivalent circuit constant that is calculated.