Multilayer Battery Insulation Sheet for Thermal Runaway Delay
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Solution Overview
Problem
Existing battery technologies face challenges in preventing thermal runaway, particularly in large format batteries used in electric vehicles and grid storage systems, where thermal runaway can propagate across multiple cells, leading to cascading failures and ignition, and current solutions like modifying electrolytes or adding insulation can impact energy density or electrochemical performance.
Innovation Solution
A thermally insulating multilayer sheet comprising a nonporous elastomeric barrier layer, a flexible foam layer, and a flame retardant component distributed within the foam layer, which provides effective thermal insulation, pressure management, and flame resistance, even in very thin configurations, to prevent thermal runaway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulation between cells is increased to reduce thermal heat transfer, then thermal runaway prevention is improved, but energy density is reduced
Solution Approach 1:
The insulation system is segmented into multiple functional layers: a flexible foam layer for primary thermal insulation, a nonporous elastomeric barrier layer for enhanced heat blocking, and a flame retardant component for fire suppression. This segmentation allows each layer to contribute differently to thermal protection, achieving effective thermal runaway prevention with reduced overall thickness compared to single-layer insulation systems.
Solution Approach 2:
The patent employs a composite multilayer structure combining materials with different thermal properties: the flexible foam layer provides low thermal conductivity for insulation, the nonporous elastomeric barrier layer provides superior heat blocking due to its nonporous structure, and the flame retardant component provides chemical fire suppression. This composite approach achieves high thermal protection performance with minimized thickness, thereby maintaining higher energy density.
2Reliability
If flame retardant additives are added to electrolyte to prevent thermal runaway, then thermal safety is improved, but electrochemical performance is negatively impacted
Solution Approach 1:
The flame retardant function is extracted from the electrolyte and relocated to a separate multilayer insulation sheet positioned between battery cells. This extraction allows the electrolyte to maintain its optimal composition for electrochemical performance while the insulation sheet provides thermal safety through its flame retardant component and multilayer structure.
Solution Approach 2:
The multilayer insulation sheet acts as an intermediary barrier between battery cells, providing thermal protection without directly contacting or interfering with the electrolyte. The flame retardant component within the insulation sheet suppresses thermal runaway propagation through physical barrier and chemical mechanisms, while the electrolyte maintains its electrochemical function undisturbed.
3Quantity of substance
If insulation thickness is reduced to maintain energy density, then energy density is improved, but thermal insulation effectiveness is reduced
Solution Approach 1:
Different regions of the insulation system have specialized properties optimized for their specific functions: the flexible foam layer provides bulk insulation with low thermal conductivity, the nonporous elastomeric barrier layer provides enhanced heat blocking at critical interfaces, and the flame retardant component provides localized fire suppression. This local optimization allows the system to achieve high thermal protection effectiveness with reduced overall thickness.
Solution Approach 2:
The patent utilizes parameter changes in material properties to enhance thermal protection in thin configurations. The nonporous elastomeric barrier layer changes the porosity parameter to create a heat-blocking layer, while the flame retardant component changes the chemical composition parameter to provide fire suppression. These parameter changes allow the insulation system to maintain high effectiveness at reduced thickness.
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 sheet effectively delays or prevents thermal runaway by reducing heat conduction and convection, maintaining thermal insulation across multiple heating and cooling cycles, and improving flame resistance, while allowing for reduced thickness and weight, thus enhancing safety and performance in battery applications.
Implementation Method 1
The flexible foam layer can include a silicone foam and the heat management layer can delay thermal runaway by at least 10 minutes when the flexible foam layer is immersed in water
Implementation Method 2
the flexible foam layer has an open-cell structure that can be imbbed with water or another liquid to increase the heat capacity of the flexible foam layer and further delay thermal runaway
Implementation Method 3
The nonporous elastomeric barrier layer can prevent water vapor transmission and can contain water within the flexible foam layer
Data Source
AI summary
A thermally insulating multilayer sheet for preventing thermal runaway includes a nonporous elastomeric barrier layer having a first and a second opposed surface; a flexible foam layer disposed on the first surface of the barrier layer; and a flame retardant component, wherein the flame retardant component is distributed within the flexible foam layer, contacts a surface of the flexible foam layer, or both.