Intumescent Battery Pad for Thermal Runaway Shielding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Large lithium-ion batteries face safety issues due to thermal runaway, which can lead to cascading fires in battery packs, and existing solutions to reduce flammability often compromise energy density or performance.
Innovation Solution
An intumescent battery pad comprising a polyurethane foam with an intumescent material containing an acid source, a carbon source, and a blowing agent is used between battery cells, providing thermal shielding and maintaining energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If increased insulation between cells is incorporated to reduce thermal heat transfer during thermal events, then flame safety is improved, but energy density is reduced
Solution Approach 1:
The foam's chemical composition is modified by incorporating intumescent materials (such as melamine, pentaerythritol, and ammonium polyphosphate) that change the material's thermal response parameters. When exposed to heat, these materials undergo chemical reactions that produce expanding gas bubbles, transforming the foam from a simple insulator to an active thermal barrier that dynamically responds to thermal threats, achieving both safety and space efficiency
Solution Approach 2:
The battery separator is constructed as a composite structure combining base polyolefin foam material with intumescent additives. This composite approach integrates the thermal insulation properties of the foam with the flame-retardant and expanding characteristics of intumescent materials, creating a multi-functional barrier that provides both passive insulation and active fire suppression while maintaining thin profile for high energy density
2Reliability
If electrolyte is modified by adding flame retardant additives or using inherently non-flammable electrolytes, then flame safety is improved, but electrochemical performance is reduced
Solution Approach 1:
The flame safety function is extracted from the electrolyte and relocated to the separator component. By placing intumescent flame-retardant materials in the separator rather than the electrolyte, the invention isolates the flame protection mechanism from the electrochemical reaction medium, allowing the electrolyte to maintain its high conductivity and performance characteristics while the separator provides independent flame suppression through intumescent expansion
3Reliability
If intumescent material is added to achieve UL-V0 flame rating, then flame safety is improved, but foam compression properties may be affected
Solution Approach 1:
The foam's mechanical parameters are optimized by carefully controlling the intumescent material concentration (typically 1-10 wt%), particle size distribution, and cross-linking density. These parameter adjustments ensure that the foam maintains sufficient compression strength (e.g., >50 kPa at 25% deflection) for battery assembly handling while containing enough intumescent material to achieve UL-V0 flame rating through proper expansion behavior during fire exposure
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 intumescent battery pad effectively prevents cascading thermal runaway events while meeting or exceeding flame safety standards and maintaining high energy densities, as demonstrated by achieving a UL-V0 rating and maintaining desired foam properties.
Implementation Method 1
an intumescent material comprising an acid source, a carbon source, and a blowing agent
Implementation Method 2
a polyurethane foam having a compression force deflection of 5 to 1,035 kilopascal at 25% deflection
Data Source
AI summary
In an aspect, an intumescent battery pad for a lithium ion battery comprises a polyurethane foam having a compression force deflection of 5 to 1,035 kilopascals at 25% deflection determined in accordance with ASTM D3574-17; and an intumescent material comprising an acid source, a carbon source, and a blowing agent; wherein the intumescent battery pad has a UL-V0 rating at a thickness of 1 millimeter. In another aspect, a battery can comprise at least two battery cells; and an intumescent battery pad located in between the at least two battery cells.