Implanted MOSFET for Controlled Battery Short Circuit Simulation
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Solution Overview
Problem
Existing methods for initiating thermal runaway in Li-ion battery cells, such as the internal short circuit techniques developed by NREL/NASA and Tsinghua University, require external heat and do not allow control over short circuit resistance, making it difficult to accurately simulate real-world short circuits and investigate the severity of thermal runaway.
Innovation Solution
A modified Li-ion battery cell incorporating a micro-size metal oxide semiconductor field effect transistor (MOSFET) with a controllable voltage source to simulate internal short circuits with varying resistances, eliminating the need for external heat and enabling precise control over short circuit resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If external heat is applied to initiate thermal runaway, then thermal runaway can be triggered, but the temperature of the trigger cell and surrounding cells increases making them less resistant to thermal runaway and complicating interpretation of results
Solution Approach 1:
The patent replaces the thermal initiation method with an electrical initiation method. Instead of using external heat to trigger thermal runaway, the invention uses an implantable electronic circuit that delivers a controlled electrical current pulse to the battery cell, causing immediate internal heating and thermal runaway without externally heating the cell or surrounding cells, thus maintaining test result interpretability
Solution Approach 2:
The patent extracts the heat generation function from the external environment and relocates it inside the battery cell through an implantable electronic circuit. The circuit is placed within the cell structure itself, allowing the heat to be generated internally at the precise location needed to trigger thermal runaway, eliminating the need for external heat application
2Reliability
If implantable internal short circuit is used to initiate thermal runaway, then thermal runaway can be triggered, but the resistance of the short circuit cannot be controlled or varied
Solution Approach 1:
The patent implements a dynamic resistance control system through the electronic circuit. The circuit can vary its output resistance to simulate different short circuit conditions, allowing researchers to study how different resistance levels affect thermal runaway severity and propagation, thus providing adaptability while maintaining reliable thermal runaway initiation
Solution Approach 2:
The patent enables parameter changes in the short circuit resistance through the electronic circuit's controllable output. By adjusting the circuit parameters, the resistance can be varied to simulate different defect severities, allowing investigation of the relationship between short circuit resistance and thermal runaway characteristics
3Ease of manufacture
If heat application is required to activate implantable short circuit, then short circuit can be initiated, but it complicates the test setup and makes results harder to interpret
Solution Approach 1:
The patent replaces the thermal activation mechanism with an electrical activation mechanism. Instead of requiring external heat to activate the implantable short circuit, the system uses an electrical signal to trigger the circuit, which then generates the necessary internal heat to initiate thermal runaway, thereby simplifying the test setup by eliminating external heating equipment
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
This approach allows for reliable and repeatable simulation of internal short circuits with controlled resistance, enabling the investigation of thermal runaway propagation and severity, and can be used to develop detection methods and mitigate hazards in battery packs without the complications of external heat application.
Implementation Method 1
A transistor having a source, a gate, and a drain is positioned in the cell. A controllable voltage source is provided, joined to the gate and source of the transistor. The transistor source is joined to a first location within the electrical cell multiple layers, and the transistor drain is electrically joined to a second location within the electrical cell multiple layers. Voltage from the controllable voltage source can reduce resistance between the transistor source and the transistor drain
Data Source
AI summary
A modified battery cell for simulating failure conditions includes a multiple layer electrical cell. A transistor having a source, a gate, and a drain is positioned in the cell. A controllable voltage source is provided, joined to the gate and source of the transistor. The transistor source is further joined to a first location within said electrical cell multiple layers, and the transistor drain is electrically joined to a second location within said electrical cell multiple layers. Voltage from the controllable voltage source can reduce resistance between said transistor source and said transistor drain for simulating a fault condition between the first location and the second location.