Internal Short Circuit Test Device for Electrochemical Cells
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Solution Overview
Problem
Existing methods for testing electrochemical cells, particularly lithium-ion rechargeable batteries, fail to reliably induce an internal short circuit under controlled conditions, which is necessary for evaluating cell behavior and safeguard systems, often resulting in cell destruction due to thermal runaway.
Innovation Solution
A test device with a switching mechanism connected to the cell's electrodes, featuring a contact substance that bridges the electrodes upon melting, allowing for a controlled and reproducible short circuit, enabling the evaluation of cell behavior and safeguard effectiveness while withstanding high short-circuit currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing test methods are used to induce internal short circuit, then thermal runaway occurs leading to cell destruction, but controlled and reproducible short circuit cannot be achieved
Solution Approach 1:
The switching device is pre-installed inside the electrochemical cell during manufacturing, with partial electrodes positioned adjacent to current-carrying electrodes and a contact substance prepared in a holding element. This preliminary arrangement enables controlled short circuit induction without requiring external intervention during testing, resolving the contradiction between reliable short circuit induction and controlled testing conditions.
2Reliability
If a complex switching mechanism is used to control short circuit, then reliable closing is achieved, but device complexity increases
Solution Approach 1:
The contact substance automatically closes the circuit through its own weight when heated and softened, eliminating the need for complex mechanical switching mechanisms. The contact substance serves itself by transitioning from a held position to bridging the gap between partial electrodes, achieving reliable closing with minimal device complexity.
Solution Approach 2:
The patent replaces complex mechanical switching mechanisms with a thermal-field-based approach. Heating elements activate the contact substance to flow and bridge electrodes, substituting mechanical actuation with thermal-field control, thereby reducing device complexity while maintaining reliable closing.
3Strength
If the switching device must withstand high short-circuit currents, then the device becomes more robust, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The switching device is designed as a disposable component installed during cell manufacturing. The contact substance and holding element are simple, inexpensive components that sacrifice themselves during the test, eliminating the need for complex, expensive, and difficult-to-manufacture robust switching mechanisms.
Solution Approach 2:
The patent changes the physical state of the contact substance from solid to liquid through temperature control. In the solid state, it can be precisely positioned in the holding element during manufacturing. When heated, it transitions to liquid state to flow and bridge electrodes, then solidifies to maintain the short circuit. This parameter change enables simple manufacturing while achieving the required electrical strength.
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 solution allows for a targeted and safe induction of internal short circuits in electrochemical cells, enabling the evaluation of cell behavior and safeguard systems, with the ability to maintain current flow until thermal runaway conditions are met or prevented, ensuring reliable testing without cell destruction.
Implementation Method 1
the contact substance is arranged such that upon transition to the short-circuit state, under the influence of gravity, it passes into the interspace between two adjacent partial electrodes
Implementation Method 2
under the influence of gravity, it passes into the interspace between two adjacent partial electrodes
Data Source
AI summary
A test device for an electrochemical cell is arranged inside the electrochemical cell in such a way that it is in electrical contact with two current-carrying electrodes of the electrochemical cell. The test device includes a switching device having at least one cathode and one anode partial electrode which are adjacently arranged, but with a space thereinbetween. In an initial state, the switching device is opened such that electrical current cannot flow between the partial electrodes. The switching device is closed in a short-circuit state by bridging the space between the partial electrodes such that an electrical current can flow between the current-carrying electrodes of the electrochemical cell and through the partial electrodes.