Multilayer Battery Pack Insulator for Thermal Runaway Flame Containment
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Solution Overview
Problem
Existing fiberglass fabric insulation in electric vehicle battery packs fails to effectively inhibit flame propagation during thermal runaway conditions, allowing flames to spread rapidly between cells at high temperatures.
Innovation Solution
A flexible multilayer insulator comprising a coating layer, a compressible layer, and an intermediate fabric layer, with the coating layer containing flame-resistant materials and the compressible layer capable of significant compression and recovery, is used to thermally isolate battery cells and prevent flame propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fiberglass fabric insulation is used in battery packs, then protection against contamination and environmental temperatures is achieved, but protection against flame propagation during thermal runaway is insufficient
Solution Approach 1:
The patent applies composite materials by combining multiple insulator layers with different properties: a first insulator layer (fiberglass fabric) for structural support and contamination protection, a second insulator layer (intumescent material) for flame propagation resistance, and an adhesive layer for bonding. This composite structure achieves superior flame protection while maintaining reasonable complexity through the systematic integration of materials with complementary functions.
Solution Approach 2:
The insulator is segmented into distinct functional layers: the first insulator layer provides mechanical support and contamination barrier, the second insulator layer provides flame propagation resistance through intumescent properties, and the adhesive layer provides bonding. This segmentation allows each layer to be optimized for its specific function, achieving high reliability without excessive overall complexity.
2Reliability
If a multilayer insulator with flame-resistant coating is used, then flame propagation is inhibited for 10 minutes at 1000-1400°C, but the insulator thickness and space occupation increase
Solution Approach 1:
The second insulator layer utilizes phase transition through intumescent material that expands when exposed to heat, forming a protective char layer. This phase transition mechanism allows the material to provide extended flame propagation resistance (10 minutes at 1000-1400°C) while maintaining a relatively thin profile, as the expansion occurs in response to thermal exposure rather than occupying space in the relaxed state.
Solution Approach 2:
The insulator design changes material parameters dynamically: the intumescent material transitions from a compact state to an expanded protective state upon thermal exposure. This parameter change allows the insulator to provide high-temperature flame protection during thermal runaway events while maintaining minimal thickness during normal operation, thus reducing space occupation under normal conditions.
3Object-affected harmful factors
If fiberglass insulator is used between battery cells, then thermal insulation during normal use is provided, but flame spreads rapidly between cells during thermal runaway
Solution Approach 1:
The patent employs composite materials by integrating a first insulator layer (fiberglass fabric) with a second insulator layer (intumescent material) and an adhesive layer. This composite construction provides both thermal insulation during normal use and flame propagation resistance during thermal runaway, addressing the harmful factor of flame spread while maintaining manufacturability through established composite material fabrication techniques.
Solution Approach 2:
The adhesive layer serves as an intermediary that bonds the first and second insulator layers together, creating a unified protective barrier between battery cells. This intermediary layer ensures that the composite insulator structure functions as an integrated system, providing both thermal insulation and flame propagation resistance without compromising manufacturing simplicity through the use of standard adhesive bonding processes.
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 multilayer insulator effectively contains and suppresses flame propagation within the battery pack for at least 10 minutes at temperatures up to 1400°C, protecting adjacent cells and maintaining the housing temperature below 200°C.
Implementation Method 1
a first layer as a coating layer... the coating material of the first layer includes flame resistant/retardant material(s)... the coating material of the first layer can withstand heat as high up to 1600° C.
Implementation Method 2
a second layer as a compressible material... the second layer of compressible material provides a compression force deflection curve that allows for significant compression and recovery properties
Implementation Method 3
an intermediate layer sandwiched between the first layer and the second layer... the intermediate layer can be provided as a fabric layer
Data Source
AI summary
A flexible multilayer battery pack insulator for an electric vehicle has a first layer of a coating material having opposite outer and inner sides, a second layer of compressible material having opposite outer and inner sides, and an intermediate fabric layer sandwiched between the inner side of the first layer and the inner side of the second layer, wherein the second layer has a relaxed thickness extending from the inner side of the second layer to the outer side of the second layer, wherein second layer can compress up to 50% of the relaxed thickness and recover to the relaxed thickness.