Expandable Gap Fillers for Battery Pack Thermal Venting Barriers
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Solution Overview
Problem
Existing thermal management systems in traction battery packs are inadequate in preventing the transfer of thermal energy during battery cell venting events, leading to potential damage to nearby structures.
Innovation Solution
Incorporation of expandable gap fillers made of high-temperature resistant foam with a low-melting point binding that transitions from a compressed to an uncompressed state upon exceeding a predefined temperature threshold, reducing free air volume and establishing a thermal barrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional thermal management systems are used in battery packs, then the structure is simple and easy to manufacture, but they are inadequate in preventing thermal energy transfer during battery cell venting events
Solution Approach 1:
The gap filler transitions from a compressed state during normal operation to an expanded state during thermal events, dynamically adapting its properties based on temperature conditions. This dynamic behavior provides thermal protection only when needed, resolving the contradiction between maintaining simple structure and providing reliable thermal prevention.
Solution Approach 2:
The gap filler's physical parameters (volume, density, thermal conductivity) change in response to temperature changes. When temperature exceeds a threshold, the material expands and its thermal insulation properties improve, enabling reliable thermal energy prevention while maintaining structural simplicity during normal operation.
2Object-affected harmful factors
If gap fillers are used to fill void spaces in battery packs, then thermal energy transfer is reduced, but the device complexity increases
Solution Approach 1:
The gap filler is self-activating through temperature-responsive expansion. It automatically transitions from compressed to expanded state when thermal conditions require protection, eliminating the need for external control systems, actuators, or complex mechanisms. This self-service capability reduces overall device complexity while effectively reducing thermal energy transfer.
Solution Approach 2:
The gap filler uses simple, inexpensive materials (foam core with melting point binder) that perform their thermal protection function during extreme events. The sacrificial nature of the binder material, which melts to trigger expansion, provides an economical solution that addresses thermal hazards without requiring complex reusable systems.
3Temperature
If the binding material has a low melting point to enable expansion, then thermal barrier formation is achieved, but the binding strength at normal temperatures may be reduced
Solution Approach 1:
The gap filler employs different materials with different properties in distinct regions: the foam core provides structural integrity and compression resistance, while the binder layer provides localized bonding with temperature-dependent behavior. This local quality differentiation allows the binder to have low melting point for trigger functionality while the foam maintains overall structural strength.
Solution Approach 2:
The gap filler combines foam material and binder material into a composite structure where each component contributes different properties. The foam provides mechanical strength and compression resistance, while the binder provides adhesion and temperature-responsive expansion capability. This composite approach resolves the contradiction between binding strength and expansion trigger temperature.
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
Effectively mitigates the transfer of thermal energy within the battery pack, preventing damage to adjacent components by significantly reducing convective heat transfer during battery cell venting.
Implementation Method 1
The expandable gap filler is configured to transition from a compressed state to an uncompressed state when a temperature near the expandable gap filler exceeds a predefined temperature threshold
Implementation Method 2
the binding is configured to melt to allow the foam portion to expand when the temperature exceeds the predefined temperature threshold
Implementation Method 3
Effectively mitigates the transfer of thermal energy within the battery pack, preventing damage to adjacent components by significantly reducing convective heat transfer during battery cell venting
Data Source
AI summary
Thermal barrier systems are provided for use within traction battery packs. An exemplary thermal barrier system may include one or more expandable gap fillers configured to transition from a compressed state to an uncompressed state when a temperature near the expandable gap filler exceeds a predefined temperature threshold. In the uncompressed state, the expandable gap filler reduces a free air volume of a void space of the traction battery pack, thereby managing or even preventing the transfer of thermal energy to nearby structures.