Battery Cell Defect Detection via Entropy-Based Graphite Interface Analysis
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Solution Overview
Problem
Defective secondary batteries can cause fires and are often identified by disassembling the cell, leading to the discard of healthy cells.
Innovation Solution
A method and system for detecting defective cells by performing charge or discharge within a specific SOC range, calculating entropy values from voltage and temperature data, and estimating the graphite interface state to determine cell defects without disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the cell is disassembled to diagnose the internal state of the secondary battery, then the defect detection capability is improved, but the loss of healthy cells increases
Solution Approach 1:
The patent replaces the mechanical disassembly method with an electrochemical measurement system. By measuring voltage, temperature, and calculating entropy changes during charge-discharge cycles, the system detects graphite interface defects without physically opening the cell, thus eliminating the waste of healthy cells while maintaining defect detection capability
Solution Approach 2:
The patent introduces entropy change as an intermediary parameter to indirectly detect graphite interface defects. Instead of directly observing the interface through disassembly, the system measures entropy changes during electrochemical reactions, which serve as a mediator to reveal the presence of defects without physical intervention
2Measurement precision
If the cell is disassembled to detect defective cells, then the detection accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical disassembly equipment with simpler electrochemical measurement devices. The system uses standard battery testing equipment to measure voltage and temperature, calculating entropy changes through software algorithms, thereby reducing device complexity while maintaining or improving detection accuracy
Solution Approach 2:
The patent creates a virtual model of the cell's internal state through entropy calculation. By measuring external parameters (voltage, temperature) and computing entropy changes, the system generates information equivalent to direct internal observation without requiring physical access to the cell interior
3Reliability
If the cell is disassembled to identify defective batteries, then the safety risk is reduced, but the productivity decreases
Solution Approach 1:
The patent performs defect detection during the formation process or early charging cycles, before the cell enters full production. By identifying defective cells early through entropy measurement during initial charge-discharge cycles, the system prevents defective batteries from reaching consumers, ensuring safety without requiring post-production disassembly
Solution Approach 2:
The patent replaces time-consuming manual disassembly and inspection processes with automated electrochemical measurement. The entropy calculation method can process multiple cells rapidly through standardized charge-discharge protocols, significantly improving throughput while maintaining safety by accurately identifying defective cells
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 non-destructive detection of defective cells, improving reliability and allowing re-formation of potentially recoverable cells, thus reducing waste and enhancing safety.
Implementation Method 1
calculating an entropy value of the cell based on the first charge/discharge data
Implementation Method 2
obtaining first charge/discharge data including voltage and temperature information during the charge or the discharge of the cell
Data Source
AI summary
A defective cell detection method includes: performing at least one of a charge or a discharge of a cell so that a state of charge (SOC) of the cell falls within a range; obtaining first charge/discharge data including voltage and temperature information during the charge or the discharge of the cell; calculating an entropy value of the cell based on the first charge/discharge data; estimating a state of a graphite interface of the cell based on the calculated entropy value; and determining whether or not the cell is defective based on the estimated state of the graphite interface of the cell.