Pouch Cell Current Interrupter for Thermal Safety
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Solution Overview
Problem
Pouch cells lack intrinsic safety mechanisms to prevent bursting due to swelling, leading to continued ionic conductivity and potential further heating during shell rupture, which is a critical issue in high-performance battery applications where voltage is limited to 60V.
Innovation Solution
A thermally induced current interrupter with a material having a negative coefficient of thermal expansion is integrated into the connection electrode, which temporarily interrupts current flow when the pouch cell temperature exceeds a threshold, preventing further charging or overcharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the pouch cell allows high current flow to achieve high performance, then power output is improved, but the risk of overheating and shell rupture increases
Solution Approach 1:
The patent incorporates a current interrupter mechanism that is pre-configured within the pouch cell structure. This mechanism proactively monitors temperature conditions and automatically interrupts current flow before the shell rupture temperature is reached, preventing the harmful effect rather than reacting after failure occurs.
Solution Approach 2:
The current interrupter is designed to autonomously detect temperature increases and interrupt current flow without external intervention. The system self-regulates by using the thermal conditions themselves to trigger the interrupter mechanism, eliminating the need for complex external monitoring systems.
2Power
If the pouch cell operates at high temperature, then power delivery is improved, but ionic conductivity persists leading to further heating and potential rupture
Solution Approach 1:
The current interrupter mechanism provides automatic feedback control by monitoring temperature conditions and responding by interrupting current flow when the threshold is approached. This creates a closed-loop safety system that continuously adjusts current flow based on thermal conditions, preventing runaway heating.
3Device complexity
If no current interruption mechanism is provided, then device complexity is reduced, but operational reliability decreases due to inability to prevent overcharging and further heating
Solution Approach 1:
The patent extracts the safety function from complex external monitoring and control systems, implementing it instead through a simple, dedicated current interrupter mechanism integrated directly into the pouch cell structure. This isolates the safety function into a separate, fail-safe component that operates independently of complex control electronics.
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 solution enhances operational reliability by preventing further heating and ensuring safe operation of battery packs in handheld power tools by interrupting current flow when the pouch cell temperature exceeds a critical threshold, thus avoiding shell rupture and associated hazards.
Implementation Method 1
The circuit breaker comprises a material with a negative coefficient of thermal expansion. The thermally induced change in the geometric dimensions of the circuit breaker is effected, according to the invention, by a change in the pouch cell temperature
Implementation Method 2
The circuit breaker can also be thermally coupled to the pouch cell only temporarily
Data Source
Figure 1a~1b
Figure 2A~2B
Figure 3
AI summary
Disclosed is a pouch cell comprising at least one terminal electrode via which the pouch cell can be electrically contacted, the pouch cell further comprising a circuit breaker which is designed to at least temporarily interrupt power consumption via the terminal electrode as a result of a thermally induced change in the geometrical dimensions of the circuit breaker. Preferably, the circuit breaker contains a material having a negative coefficient of thermal expansion, and the thermally induced change in the geometrical dimensions of the circuit breaker is brought about by a change in a pouch cell temperature.