Lithium Deposition Detection in Li-Ion Batteries via Internal Resistance
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Solution Overview
Problem
Existing methods for determining lithium deposition in nonaqueous electrolyte solution type lithium ion secondary batteries struggle to accurately distinguish between lithium deposition and age-related deterioration, leading to low determination accuracy.
Innovation Solution
A system that includes a discharge amount obtaining portion, an internal resistance obtaining portion, and a correlation map to determine lithium deposition by comparing the discharge amount and internal resistance values of a target battery against a reference battery that has only aged, using a correlation map to differentiate between lithium deposition and age-related deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If power storage capacity comparison method is used to determine lithium deposition, then the determination can be made without taking the battery apart, but the determination accuracy is low because age-related deterioration also causes capacity decrease
Solution Approach 1:
The patent segments the determination process into multiple independent measurement components: power storage capacity, internal resistance, and charge acceptance rate. Each parameter is measured and evaluated separately, then integrated to achieve accurate lithium deposition determination while maintaining ease of operation.
Solution Approach 2:
The patent introduces additional measurement parameters (internal resistance and charge acceptance rate) beyond the single power storage capacity parameter. By monitoring multiple parameters simultaneously and comparing their rates of change, the system can distinguish between capacity loss due to lithium deposition versus age-related deterioration, thereby improving determination accuracy without complicating the operational process.
2Device complexity
If single parameter (power storage capacity) monitoring is used, then the system complexity is low, but the ability to distinguish lithium deposition from age-related deterioration is insufficient
Solution Approach 1:
The patent merges multiple measurement functions (power storage capacity measurement, internal resistance measurement, and charge acceptance rate measurement) into a single integrated determination system. These measurements are performed using existing battery system components, and the results are combined through computational analysis to achieve accurate lithium deposition determination without requiring separate complex diagnostic equipment.
Solution Approach 2:
The patent makes the determination system multi-functional by using a single integrated approach that simultaneously evaluates power storage capacity, internal resistance, and charge acceptance rate. This universal system can distinguish between lithium deposition and age-related deterioration while maintaining low device complexity, as it leverages existing battery operational data and standard measurement capabilities.
Data Source
AI summary
A battery system includes a discharge amount obtaining portion that obtains a discharge amount (determination zone discharge amount) from a determination start voltage until a predetermined determination end voltage of a battery; an internal resistance obtaining portion that obtains an internal resistance value of the battery; a correlation map in which a combination of internal resistance value information and determination zone discharge amount information for a battery that is the same kind as a target of a determination and in which lithium deposition has not occurred is stored for each degree of age-related deterioration of the battery; and a deposition determining portion that determines a degree of lithium deposition in the target battery by comparing the determination zone discharge amount during the determination of the target battery with the internal resistance value during the determination of the target battery on the same scale by converting at least one via the correlation map.