Core-Sheath Heat Transfer Suppression Sheet for Battery Cell Expansion

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Solution Overview

Problem

Existing heat insulation sheets in battery packs face challenges due to increased expansion rates of battery cells during charging and discharging, leading to compression, powder falling, and a decrease in heat insulation performance.

Innovation Solution

A method for producing a heat transfer suppression sheet using a mixture of inorganic particles, binder fibers with a core-sheath structure, and hot melt powder, processed into a sheet to achieve high strength, retain shape, and suppress powder falling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a heat insulation sheet is disposed between battery cells to suppress heat propagation, then heat insulation performance is improved, but the sheet is compressed by battery cell expansion during charging and discharging, causing powder falling and strength degradation

Engineering Contradiction:

Improveheat insulation performanceVSAvoidsheet strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The heat insulation sheet uses a composite structure combining inorganic particles (silica, metal oxide) with organic binding materials (fibers, binders, heat-resistant resins). This composite material approach provides both heat insulation performance and mechanical strength to resist compression from battery cell expansion, preventing powder falling while maintaining thermal isolation effectiveness.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the heat insulation sheet contains inorganic particles and binding materials to maintain heat insulation property under compressive stress, then heat insulation performance is improved, but powder falling occurs reducing the effectiveness

Engineering Contradiction:

Improveheat insulation performanceVSAvoidpowder falling

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent specifies particular ranges for inorganic particle size (0.1-10 μm) and binding material content (1-20 parts by mass per 100 parts inorganic particles) to optimize the balance between heat insulation performance and powder falling suppression. By controlling these parameters, the sheet maintains structural integrity under compression while preserving thermal isolation properties.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The heat insulation sheet employs different materials with specific local functions: inorganic particles provide heat insulation, while organic fibers and binders provide structural framework and binding. This local quality differentiation ensures that each component performs its specific function optimally, with the binding materials preventing inorganic particle dispersion while the inorganic particles maintain thermal isolation.

Inventive Principle:

Principle #3Local quality

3Quantity of substance

If battery cell capacity is increased to improve energy density, then energy storage capability is improved, but expansion rate during charging and discharging increases, causing greater compression of heat insulation sheets

Engineering Contradiction:

Improvebattery capacityVSAvoidcompressive stress on heat insulation sheet

Core Design Contradiction:

Quantity of substanceVSStress or pressure

Solution Approach 1:

The heat insulation sheet is pre-installed between battery cells with sufficient thickness and mechanical strength to accommodate anticipated expansion during charging and discharging cycles. The binding materials are selected to maintain sheet integrity under the expected compressive stress ranges, preventing powder falling even as battery capacity and expansion rates increase.

Inventive Principle:

Principle #10Preliminary action

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 resulting heat transfer suppression sheet maintains excellent heat insulation performance while providing high strength and preventing powder falling, effectively suppressing thermal runaway and flame spread in battery packs.

Implementation Method 1

a melting point of a first organic material constituting the core portion is higher than a melting point of a second organic material constituting the sheath portion and a melting point of a third organic material constituting the hot melt powder

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentUS20250183418A1Method for producing heat transfer suppression sheet, heat transfer suppression sheet, and battery pack

Publication Date: 2025.06.05 IBIDEN CO LTD

AI summary

A method for producing a heat transfer suppression sheet contains processing a mixture containing an inorganic particle, a binder fiber having a core-sheath structure, and a hot melt powder into a sheet. The binder fiber having a core-sheath structure includes a core portion extending in its longitudinal direction, and a sheath portion formed to cover an outer peripheral surface of the core portion, and a melting point of a first organic material constituting the core portion is higher than a melting point of a second organic material constituting the sheath portion and a melting point of a third organic material constituting the hot melt powder.