Pouch Cell Directional Venting for Thermal Runaway Containment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Large lithium-ion battery systems face a significant risk of fire and explosion due to thermal runaway and the propagation of flammable gases, primarily caused by internal shorts in the cells, which can lead to cascading failures within the battery system.
Innovation Solution
The battery system incorporates polymer or pouch cells with a directional venting mechanism that releases gases in a controlled manner when pressure exceeds a threshold, utilizing score lines or weakened seams to direct gases away from the cell assembly, and interleaved barrier structures to prevent heat and electrolyte sharing between cells, along with endothermic materials to manage temperature and reduce the risk of ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If polymer cells are used in large battery systems, then energy storage capacity is improved, but the risk of thermal runaway and fire propagation increases
Solution Approach 1:
The battery system is divided into multiple modules, each containing individual polymer cells separated by barrier structures. This segmentation isolates thermal runaway events to specific cells or modules, preventing propagation to the entire battery system while maintaining high overall energy storage capacity.
Solution Approach 2:
Interleaved barrier structures act as intermediary elements between adjacent polymer cells. These barriers include heat-resistant materials and gas-flow directing features that intercept and redirect thermal and gaseous hazards, preventing direct transmission of thermal runaway between cells.
2Productivity
If cells are densely packaged to optimize space, then productivity is improved, but the risk of cascading failure increases
Solution Approach 1:
The battery system is divided into multiple modules, each containing individual polymer cells separated by barrier structures. This segmentation isolates thermal runaway events to specific cells or modules, preventing propagation to the entire battery system while maintaining high overall energy storage capacity.
Solution Approach 2:
Interleaved barrier structures act as intermediary elements between adjacent polymer cells. These barriers include heat-resistant materials and gas-flow directing features that intercept and redirect thermal and gaseous hazards, preventing direct transmission of thermal runaway between cells.
3Reliability
If a sealed enclosure is used to protect battery cells, then reliability is improved, but pressure buildup from gas generation can cause explosions
Solution Approach 1:
Score lines are pre-formed in the pouch structure at specific locations before battery operation. These predetermined weak points ensure that when pressure builds up during thermal runaway, the pouch fails in a controlled manner at the score lines rather than randomly, directing gas flow through safe pathways.
Solution Approach 2:
The pouch structure is designed with removable or sacrificial features (score lines, weakened seams) that can be selectively removed or failed to release pressure. This allows the sealed enclosure to maintain its protective function while providing controlled pressure relief mechanisms to prevent explosions.
4Reliability
If thermal insulation materials are added to prevent heat propagation, then reliability is improved, but device complexity increases
Solution Approach 1:
The interleaved barrier structures serve multiple functions simultaneously: they provide thermal insulation to prevent heat propagation, guide gas flow through their geometric features, and act as physical separators between cells. This multi-functionality reduces the need for additional dedicated components, maintaining structural simplicity while achieving reliable heat propagation prevention.
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 effectively reduces the potential for cascading failures by controlling gas release and managing heat, thereby minimizing the risk of fires and explosions within the battery system, enhancing safety and reliability.
Implementation Method 1
in response to an increase in pressure within the polymer/pouch cell, e.g., a pressure increase beyond a threshold level, the polymer/pouch releases gasses in a directionally controlled manner
Implementation Method 2
interleaved barrier structures that may include surface features to direct the flow of gasses and that prevent heat transfer between the polymer cells
Implementation Method 3
along with endothermic materials to manage temperature and reduce the risk of ignition
Data Source
AI summary
Battery systems are provided that include polymer cells/pouch cells. The polymer cells/pouch cells are structured such that, in response to an increase in pressure within the polymer/pouch cell, e.g., a pressure increase beyond a threshold level, the polymer/pouch releases gasses in a directionally controlled manner so as to facilitate withdrawal of the gasses from the battery enclosure through a vent structure that is positioned for ease of communication with the released gasses. The battery enclosure is generally sealed, e.g., hermetically sealed, and the polymer cells/pouch cells may be spaced from each other, e.g., by a support structure that may include interleaved barrier structures.