Thermal Runaway Suppression Sheet With Planar Heat Diffusion
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Solution Overview
Problem
Existing thermal runaway suppression sheets for battery packs fail to effectively manage high-temperature thermal runaway events, as the matrix resin in endothermic material layers melts or carbonizes, compromising fire resistance, and the inclusion of inorganic particles leads to thickness issues and powder fall-off concerns, while maintaining a lightweight and thin profile.
Innovation Solution
A thermal runaway suppression sheet comprising a silica-based inorganic fiber thermal energy consumption layer with hydroxyl groups and a thermal diffusion layer with high planar thermal conductivity, utilizing expanded graphite or boron nitride, to consume and diffuse thermal energy effectively, maintaining a thickness of 3 mm or less without inorganic particles that cause powder issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a thermal runaway suppression sheet with endothermic material layer containing matrix resin is used, then thermal energy absorption is improved, but the matrix resin melts or carbonizes at high temperature causing loss of fire resistance
Solution Approach 1:
The invention extracts and removes the organic matrix resin component from the endothermic material layer, replacing it entirely with inorganic particles. This extraction eliminates the melting and carbonization problems while preserving the endothermic heat absorption function through inorganic hydrate decomposition reactions.
Solution Approach 2:
The invention changes the material composition parameters from organic-based to inorganic-based. Specifically, it uses inorganic particles such as metal hydroxides (Al(OH)3, Fe(OH)3) and their hydrates, which maintain structural stability and fire resistance at high temperatures while still providing endothermic heat absorption through controlled decomposition.
2Temperature
If inorganic particles are added to the thermal runaway suppression sheet, then thermal insulation is improved, but the sheet thickness increases and powder fall-off occurs
Solution Approach 1:
The invention employs porous inorganic particles with controlled pore structures that provide effective thermal insulation through air entrapment and reduced thermal conductivity. The porous structure increases thermal resistance without requiring proportional increases in sheet thickness, as the pores themselves act as insulating barriers.
Solution Approach 2:
The invention creates a composite material system combining inorganic particles (for thermal insulation and endothermic reaction), binder materials (for structural integrity), and potentially other functional components. This composite approach optimizes the balance between thermal insulation performance and sheet thickness while preventing powder fall-off through proper material selection and formulation.
3Weight of moving object
If the thermal runaway suppression sheet is made thinner to maintain lightweight profile, then weight and thickness are reduced, but effectiveness in managing high-temperature thermal runaway is compromised
Solution Approach 1:
The invention changes the thermal management mechanism from relying on thick organic layers to using inorganic particles with high specific heat capacity and endothermic decomposition reactions. This parameter change allows thin sheet design while maintaining or enhancing thermal runaway suppression effectiveness through chemical heat absorption rather than just physical barrier thickness.
Solution Approach 2:
The invention utilizes phase transition reactions of inorganic hydrates (e.g., Al(OH)3 → Al2O3 + H2O) that absorb large amounts of heat at relatively low temperatures during thermal runaway events. This phase change mechanism provides intense endothermic cooling in a thin layer, effectively suppressing thermal runaway without requiring thick sheets.
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 sheet effectively reduces temperatures below 400°C when exposed to 1000°C, preventing thermal runaway propagation and ensuring a lightweight, thin, and durable solution for battery packs.
Implementation Method 1
a thermal energy consumption layer composed of a sheet made of silica-based inorganic fiber having a hydroxyl group
Implementation Method 2
a thermal diffusion layer having a thermal conductivity in a planar direction that is from 10 to 200 times as high as a thermal conductivity in a thickness direction
Implementation Method 3
utilizing expanded graphite or boron nitride, to consume and diffuse thermal energy effectively
Data Source
AI summary
Provided are a thermal runaway suppression sheet with maximum thickness of 3 mm or less and capable of insulating to temperature at which a propagation of thermal runaway in a lithium ion battery can be suppressed, and a battery pack and a battery module. The thermal runaway suppression sheet includes a thermal energy consumption layer containing a silica-based inorganic fiber having a hydroxyl group, and a thermal diffusion layer having a thermal conductivity in the planar direction that is 10 to 200 times as high as the thermal conductivity in the thickness direction. The thermal runaway suppression sheet has a thickness of 3 mm or less. When the thermal runaway suppression sheet is locally heated, the thermal energy consumption effect based on the silica-based inorganic fibers contained in the thermal energy consumption layer can be efficiently utilized by the thermal conduction along the planar direction of the thermal diffusion layer.