Crosslinked Inorganic Separator Coating for Heat-Stable Li-Ion Cells

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Solution Overview

Problem

Existing separators for lithium-ion secondary batteries (LIBs) face challenges in achieving uniform crosslinked structures due to non-uniform light irradiation, leading to deformation and safety issues when heated, and there is a need for improved cycle characteristics and safety in electricity storage devices.

Innovation Solution

A separator for electricity storage devices comprising a polyolefin resin microporous membrane with a silane graft-modified polyolefin and an inorganic porous layer, featuring covalent bonding and controlled peeling ratio, which initiates a silane crosslinking reaction upon contact with an electrolyte solution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a crosslinked structure is formed in the microporous membrane by light irradiation, then heat resistance is improved, but the crosslinked structure becomes non-uniform causing deformation when heated

Engineering Contradiction:

Improveheat resistanceVSAvoiduniformity of crosslinked structure

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

The patent replaces light irradiation (electromagnetic energy) with electron beam irradiation (particle beam energy) to form the crosslinked structure. This substitution eliminates the non-uniformity problem caused by light scattering and absorption, as electron beams can be precisely controlled to achieve uniform energy distribution throughout the microporous membrane, resulting in a uniform crosslinked structure that prevents deformation when heated

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the energy type parameter from photons (light) to electrons (particle beam) and adjusts the irradiation conditions to achieve uniform crosslinking. By controlling electron beam parameters such as acceleration voltage, current density, and scanning speed, the patent achieves uniform energy deposition and uniform crosslinked structure formation throughout the membrane thickness

Inventive Principle:

Principle #35Parameter changes

2Temperature

If the inorganic porous layer is arranged on the microporous membrane, then heat resistance is improved, but the bonding between layers becomes insufficient leading to peeling

Engineering Contradiction:

Improveheat resistanceVSAvoidbonding strength between layers

Core Design Contradiction:

TemperatureVSStrength

Solution Approach 1:

The patent replaces simple physical adhesion or conventional chemical bonding with covalent bonding formed by electron beam irradiation. The electron beam induces covalent bonds between the polyolefin resin and the inorganic porous layer, creating strong chemical bonds that prevent peeling while maintaining heat resistance. This covalent bonding mechanism is superior to physical adhesion in terms of bonding strength and thermal stability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates a composite structure where the inorganic porous layer and polyolefin resin are chemically bonded through covalent bonds formed by electron beam irradiation. This composite material approach combines the heat resistance of the inorganic layer with the flexibility and bonding capability of the polyolefin resin, achieving both high heat resistance and strong interlayer bonding that prevents peeling

Inventive Principle:

Principle #40Composite materials

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 solution enhances the cycle characteristics and safety of electricity storage devices by ensuring uniform crosslinked structures and controlled peeling, preventing deformation and improving performance in heating tests.

Implementation Method 1

a silane crosslinking reaction in the silane graft-modified polyolefin is initiated when the separator for an electricity storage device is brought into contact with an electrolyte solution

Methodology Applied

Scientific EffectSilane crosslinking reaction: Chemical Bonding

Data Source

PatentUS12512560B2Inorganic coating layer crosslinked separator

Publication Date: 2025.12.30 ASAHI KASEI BATTERY SEPARATOR CORP

AI summary

There is provided a separator for an electricity storage device, comprising a polyolefin resin microporous membrane and an inorganic porous layer arranged on at least one surface of the polyolefin resin microporous membrane, whereinthe inorganic porous layer has at least one selected from the group consisting of (i) covalent bonding between inorganic particles, (ii) covalent bonding between resin binders, and (iii) covalent bonding between an inorganic particle and a resin binder, andthe polyolefin resin microporous membrane comprises a silane graft-modified polyolefin, and a silane crosslinking reaction in the silane graft-modified polyolefin is initiated when the separator for an electricity storage device is brought into contact with an electrolyte solution.