Battery Cell Rupture Membrane With Thermal Ignition Venting
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Solution Overview
Problem
High-voltage battery cells, particularly lithium-ion batteries, face risks of thermal runaway due to mechanical impacts, overcharging, or short circuits, which can lead to overheating, electrolyte evaporation, and critical overpressure, potentially damaging the entire battery module.
Innovation Solution
A battery cell design featuring a rupture membrane with an integrated ignitable material, such as a thermite mixture of iron(III) oxide and aluminum, which ignites at a critical temperature to open the rupture membrane, allowing gas escape and reducing internal pressure before thermal runaway occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rupture membrane is used for overpressure relief, then gas escape is enabled and overpressure is relieved, but the rupture membrane may not open reliably at the critical temperature before thermal runaway occurs
Solution Approach 1:
The patent replaces the purely mechanical pressure-based rupture mechanism with a thermally activated chemical system. The ignitable material undergoes exothermic combustion when exposed to heat, generating sufficient thermal energy to rupture the membrane. This substitution enables reliable activation at critical temperatures before thermal runaway, overcoming the limitation of pressure-dependent mechanical rupture systems.
Solution Approach 2:
The invention changes the activation parameter from pressure (mechanical system) to temperature (thermal system). By using ignitable material that combusts at a specific critical temperature, the rupture membrane opens reliably when thermal runaway is imminent, regardless of the pressure build-up rate. This parameter change allows proactive safety intervention before catastrophic failure.
2Reliability
If the rupture membrane is made more fragile to ensure it bursts at critical pressure, then overpressure relief is improved, but the membrane may burst during production or conventional operation
Solution Approach 1:
The patent replaces the mechanical pressure-dependent rupture system with a thermally activated chemical system. The ignitable material requires a specific critical temperature to initiate combustion, which only occurs under abnormal conditions (thermal runaway). This eliminates the risk of premature rupture during production or normal operation, as these conditions do not generate the required critical temperature.
Solution Approach 2:
The invention changes the activation threshold from pressure to temperature. By selecting ignitable material with a specific combustion temperature well above normal operating pressures but below thermal runaway temperatures, the system achieves selective activation. The membrane remains intact during production and normal operation but reliably ruptures when critical thermal conditions are reached.
3Reliability
If ignitable material is added to enable thermal activation of the rupture membrane, then reliable opening at critical temperature is achieved, but the device complexity increases
Solution Approach 1:
The patent merges the ignitable material directly with the rupture membrane structure, forming an integrated safety component. The ignitable material is positioned in direct contact with or adjacent to the membrane, eliminating the need for separate activation mechanisms, sensors, or control systems. This merging approach achieves reliable thermal activation while minimizing structural complexity.
Solution Approach 2:
The ignitable material serves dual functions: it acts as both the activation mechanism and the energy source for membrane rupture. When exposed to critical temperatures, the material self-ignites through exothermic combustion, generating the necessary heat to rupture the membrane without requiring external triggers, sensors, or control systems. This self-service approach simplifies the overall device structure.
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 effectively prevents overpressure buildup and reduces the risk of thermal runaway by allowing gas escape and increasing internal resistance through electrolyte release, thereby enhancing the safety of the battery module.
Implementation Method 1
an ignitable material is disposed which is configured to ignite and thereby to open the rupture membrane on overheating of the battery cell casing
Implementation Method 2
At high temperatures, there may in particular be evaporation of the electrolyte contained in the battery cell, causing a critical overpressure in the battery cell
Implementation Method 3
As the escape of the electrolyte gas is an endothermic reaction, the cell temperature can be reduced as a result
Data Source
AI summary
A battery cell including a battery cell casing having a rupture membrane, an electrode unit disposed in the battery cell casing, and an ignitable material that is disposed in a region of the rupture membrane and is configured to ignite and thereby open the rupture membrane on overheating of the battery cell casing and/or of the battery cell is provided. A battery module including a plurality of battery cells is further provided.