Heat Transfer Suppression Sheet for Battery Packs
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Solution Overview
Problem
Existing heat insulating materials in battery packs are ineffective in preventing the reduction of insulating properties due to dew condensation water and electrolytic solution infiltration, leading to potential short-circuits and thermal runaway.
Innovation Solution
A heat transfer suppression sheet containing inorganic or organic fibers and a liquid repellent substance with a surface tension lower than water, which adheres to the surface and inside of the sheet to prevent water and electrolyte infiltration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heat insulating material is disposed between battery cells to suppress fire spreading, then thermal runaway propagation is prevented, but dew condensation water and electrolytic solution infiltration reduces insulating properties causing short-circuits
Solution Approach 1:
The patent uses a composite heat insulating material consisting of hydrophobic inorganic particles (such as hydrophobic silica) dispersed in a binder resin matrix. This composite structure combines the heat insulation properties of inorganic materials with the liquid-repelling characteristics of hydrophobic particles, while the binder resin provides structural integrity. The composite nature allows simultaneous achievement of thermal insulation and liquid infiltration resistance.
Solution Approach 2:
The patent modifies the surface properties of inorganic particles by making them hydrophobic through surface treatment or selection of specific materials. This parameter change in surface energy causes the particles to repel water and electrolytic solutions. The hydrophobicity parameter is specifically controlled to ensure liquid repellency while maintaining heat insulation performance.
2Temperature
If conventional heat insulating material is used, then thermal insulation is provided, but insulating properties deteriorate when electrolytic solution infiltrates at high temperature
Solution Approach 1:
The patent employs a composite material system where hydrophobic inorganic particles are embedded in a heat-resistant binder resin. This composite structure maintains structural stability at high temperatures while the hydrophobic particles continue to repel electrolytic solutions. The binder resin is selected to withstand thermal conditions without degrading, ensuring long-term reliability.
Solution Approach 2:
The patent uses a binder resin that may degrade at very high temperatures, but this is acceptable because the hydrophobic inorganic particles maintain their liquid-repelling function even if the binder degrades. The system is designed so that the critical function (liquid repellency) is maintained by the more stable inorganic component.
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 suppresses the infiltration of dew condensation water and electrolytic solutions, maintaining insulating properties and preventing short-circuits and thermal runaway in battery packs.
Implementation Method 1
a liquid repellent substance having a surface tension smaller than a surface tension of water
Implementation Method 2
heat transfer suppression sheet to be interposed between a plurality of battery cells
Data Source
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AI summary
There are provided a heat transfer suppression sheet which has excellent heat insulating properties and also prevents the infiltration of water, which makes it possible to prevent ignition and the like due to a short circuit between battery cells, and preferably makes it possible to prevent a decrease in heat insulating properties due to the infiltration of the electrolytic solution, and a battery pack having the heat transfer suppression sheet. A heat transfer suppression sheet (10) interposed between a plurality of battery cells contains at least one kind of fiber (glass fiber (1)) selected from an inorganic fiber and an organic fiber, and a liquid repellent substance (2) having a surface tension smaller than a surface tension of water.