Battery Cell Voltage Inflection Diagnosis for Internal Short Risk
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Solution Overview
Problem
Secondary battery cells are prone to internal short circuits due to separator failure, deformation, or dendrite formation, leading to safety issues like thermal runaway, which existing technologies fail to effectively detect and prevent.
Innovation Solution
A battery diagnosis device that monitors cell voltage changes over time, identifies an inflection point where the rate of voltage decrease transitions from decreasing to increasing, and classifies cells as abnormal based on predetermined conditions, such as a voltage decrease rate of 0.7 mV/h after the inflection point, to proactively detect potential internal short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing battery monitoring technologies are used, then the battery system operates with standard monitoring capabilities, but internal short circuits cannot be detected early enough to prevent thermal runaway
Solution Approach 1:
The system performs preliminary diagnosis by monitoring voltage changes during a negligence test period before the battery is put into service. This early detection approach identifies cells with internal short circuits before they can cause thermal runaway, preventing the safety issue before it occurs.
Solution Approach 2:
The invention replaces physical inspection or invasive testing methods with electrical measurement-based diagnosis. By monitoring voltage changes over time during a negligence test, the system detects internal short circuits through electrical parameters rather than mechanical means, enabling non-invasive early detection.
2Reliability
If proactive diagnosis is implemented to detect potential internal short circuits, then safety against thermal runaway is improved, but the device complexity increases due to additional monitoring and analysis requirements
Solution Approach 1:
The battery cell itself provides the diagnostic information through its voltage response during the negligence test. The cell's electrical characteristics during this test period reveal whether it has internal short circuits, eliminating the need for separate active testing equipment or complex external diagnostic devices.
Solution Approach 2:
The system diagnoses internal short circuits by monitoring changes in voltage parameters over time during the negligence test. By analyzing the rate of voltage decrease and detecting inflection points in the voltage-time curve, the system identifies abnormal cells using parameter analysis rather than complex structural modifications.
Data Source
AI summary
A battery diagnosis method, a battery diagnosis device and a battery pack performing the same. The battery diagnosis device may include a detection device that detects a cell voltage of a battery cell and a diagnosis device. The diagnosis device calculates a rate of voltage decrease over time of the cell voltage if a negligence test of the battery cell is initiated, and detects an inflection point at which the rate of voltage decrease changes from a decreasing trend to an increasing trend. The diagnosis device diagnoses the battery cell as an abnormal battery cell if the inflection point is detected.