Battery Cell Impedance Phase Shift Thermal Runaway Detection
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Solution Overview
Problem
Lithium-ion batteries face challenges in effectively monitoring and preventing thermal runaway events, which can lead to cascading cell failures and fires, as existing methods like surface temperature monitoring are not sufficiently effective and can be costly and complex.
Innovation Solution
A battery cell evaluation apparatus that measures impedance phase shift between an applied current and voltage across the cell terminals, using a current source, measurement circuitry, and control circuitry to compare the phase shift data to a protection profile and trigger protective measures before thermal runaway occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surface temperature monitoring using thermocouples is implemented on each cell, then thermal runaway detection capability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts the temperature sensing function from physical thermocouple contacts and implements it through electrical impedance measurement. By measuring the impedance of the cell terminals, the system can detect temperature changes and thermal runaway conditions without requiring physical temperature sensors on each cell, thereby reducing assembly complexity while maintaining detection capability
Solution Approach 2:
The patent replaces the mechanical/physical thermocouple contact system with an electrical measurement system. Instead of using physical sensors that require mechanical attachment to each cell, the system uses electrical impedance measurements through the existing cell terminals to detect thermal conditions, eliminating the need for additional mechanical components and simplifying assembly
2Reliability
If surface temperature monitoring using thermocouples is implemented on each cell, then thermal runaway detection capability is improved, but manufacturing cost increases
Solution Approach 1:
The patent makes the cell terminals serve multiple functions: they are used for both normal electrical connection and for thermal runaway detection through impedance measurement. This multi-functionality eliminates the need for separate thermocouple components, reducing part count and manufacturing cost while maintaining the ability to detect thermal runaway conditions
Solution Approach 2:
The patent enables the cell itself to provide the sensing function through its own electrical impedance characteristics. The cell terminals and internal structure serve as the sensing element, eliminating the need for external sensing components. The system uses the cell's inherent electrical properties to detect thermal conditions, thereby reducing manufacturing cost
3Device complexity
If simple voltage monitoring is used, then device complexity is reduced, but measurement precision for detecting thermal runaway conditions deteriorates
Solution Approach 1:
The patent changes the measurement parameter from simple voltage to electrical impedance. By measuring impedance (which includes both resistance and reactance components), the system gains more sensitive and accurate detection of thermal runaway conditions. Impedance changes provide earlier and more precise indication of cell degradation and thermal runaway compared to voltage alone, while still using simple electrical measurement circuitry
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
The apparatus effectively predicts and prevents thermal runaway by monitoring impedance phase shift, reducing the risk of cell failures and fires, and can be implemented with minimal additional size and power requirements, enhancing battery safety and management.
Implementation Method 1
receive a measurement of an impedance phase shift of the cell as phase shift data from the measurement circuitry. In this regard, the measurement circuitry may be configured to measure, due to application of the current, the impedance phase shift between the current and a voltage across the terminals of the cell
Data Source
AI summary
A battery cell evaluation apparatus is provided that includes a current source configured to output a current at a frequency, measurement circuitry, and control circuitry. The control circuitry may be configured to electrically connect a cell of a battery to the current source and the measurement circuitry to apply the current across terminals of the cell and receive a measurement of an impedance phase shift of the cell as phase shift data from the measurement circuitry. The control circuitry may also be configured to compare the phase shift data to a protection profile, and trigger a protection device to prevent damage to the battery based on the comparison of the phase shift data to the protection profile.