Composite Thermal Sheet for Battery Thermal Runaway Barriers
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Solution Overview
Problem
Existing battery technologies face challenges in effectively managing thermal runaway, particularly in large format lithium-ion batteries, where thermal runaway in one cell can propagate to adjacent cells, leading to cascading events and potential ignition, with existing solutions either compromising electrochemical performance or limiting energy density.
Innovation Solution
A composite thermal management sheet comprising a silicone foam layer with a reactive filler composition that generates water upon heat exposure, forming a thermal barrier layer to absorb and redirect heat, thereby preventing the spread of thermal events between cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulation between cells is increased to reduce thermal heat transfer, then thermal runaway propagation is reduced, but energy density is limited
Solution Approach 1:
The invention changes the thermal properties of the insulation material by incorporating phase change materials that undergo phase transitions at specific temperatures. This allows the material to provide enhanced thermal protection during thermal runaway events while maintaining thinner overall insulation layers, thereby preserving energy density.
Solution Approach 2:
The invention uses composite insulation materials combining traditional insulation substances with phase change materials or endothermic decomposition materials. This composite structure provides both thermal insulation and active thermal management through phase change or chemical reactions, achieving better thermal runaway prevention without increasing insulation thickness excessively.
2Reliability
If flame retardant additives are added to electrolyte to prevent thermal runaway, then thermal runaway is reduced, but electrochemical performance is negatively impacted
Solution Approach 1:
The invention extracts the flame retardant function from the electrolyte by placing it in the insulation material between cells. This separation allows the electrolyte to maintain its optimal electrochemical performance while the insulation material provides thermal protection through flame retardant additives or phase change materials.
Solution Approach 2:
The invention introduces an intermediary insulation material between cells that contains flame retardant additives or phase change materials. This intermediary layer provides thermal protection without directly contacting the electrolyte, thus preventing negative impacts on electrochemical performance while still achieving thermal runaway prevention.
3Reliability
If thicker insulation material is used to delay thermal runaway propagation, then thermal runaway spread is reduced, but battery size and weight increase
Solution Approach 1:
The invention changes the thermal response characteristics of the insulation material by incorporating phase change materials that absorb large amounts of heat during phase transitions. This allows thinner insulation layers to provide equivalent or superior thermal protection compared to thicker traditional insulation, thereby reducing battery weight.
Solution Approach 2:
The invention utilizes phase transitions of incorporated materials (such as paraffin, fatty acids, or salt hydrates) that occur at temperatures relevant to battery thermal runaway. These phase changes absorb significant heat energy, providing enhanced thermal protection in thinner material layers, thus reducing overall battery weight while maintaining safety.
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 composite thermal management sheet effectively delays or prevents thermal runaway propagation, maintains electrochemical performance, and enhances energy density by creating a flexible thermal barrier that absorbs and redirects heat, reducing the risk of cell ignition.
Implementation Method 1
a first filler that decomposes to generate water upon initial exposure to heat
Implementation Method 2
a second filler different from the first filler, wherein the second filler forms a thermal barrier layer with a decomposition product of the first filler, or absorbs the water
Implementation Method 3
forming a thermal barrier layer to absorb and redirect heat, thereby preventing the spread of thermal events between cells
Data Source
AI summary
A composite thermal management sheet for a battery includes a silicone foam layer; and a reactive filler composition disposed within the silicone foam layer, the reactive filler composition including a first filler that decomposes to generate water upon initial exposure to heat; and a second filler different from the first filler, wherein the second filler forms a thermal barrier layer with a decomposition product of the first filler, or absorbs the water, or both.