PEI Nanocomposite Battery Separator for Thermal Stability and Ion Transport

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Solution Overview

Problem

Existing lithium-ion battery (LIB) separators made from polyethylene and polypropylene suffer from poor thermal stability, low electrolyte wettability, and high flammability, leading to safety risks such as fire or explosion, and require complex and costly fabrication processes to improve their performance.

Innovation Solution

A heat-resistant and flame-retardant porous composite membrane is developed using polyetherimide (PEI) and ceramic nanowires or nanofibers, fabricated via a non-solvent-induced phase separation process, resulting in an interconnected porous network with excellent flexibility, thermal stability, and superior tensile strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If polyethylene or polypropylene separators are used, then low cost and excellent electrochemical stability are achieved, but poor thermal stability and high flammability result

Engineering Contradiction:

Improveelectrochemical stabilityVSAvoidthermal stability

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent employs a composite structure consisting of a polyolefin separator base layer combined with a ceramic coating layer containing metal oxide particles (such as Al2O3, SiO2, TiO2) and binder polymers. This composite design allows the polyolefin to provide electrochemical stability while the ceramic coating imparts thermal stability and flame retardancy, resolving the contradiction between these two properties.

Inventive Principle:

Principle #40Composite materials

2Reliability

If polyethylene or polypropylene separators are used, then low cost and excellent electrochemical stability are achieved, but poor electrolyte wettability and low ion conductivity result

Engineering Contradiction:

Improveelectrochemical stabilityVSAvoidelectrolyte wettability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent applies local quality modification by coating only the surface of the polyolefin separator with ceramic materials and binder polymers. The bulk polyolefin maintains its electrochemical stability while the coated surface layer provides enhanced electrolyte wettability through the binder polymer matrix and porous ceramic structure, allowing local optimization of different properties in different regions of the separator.

Inventive Principle:

Principle #3Local quality

3Ease of operation

If surfaces of PE or PP separators are coated with particulate inorganic materials, then electrolyte wettability is improved, but fabrication complexity and cost increase

Engineering Contradiction:

Improveelectrolyte wettabilityVSAvoidfabrication complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent merges the ceramic particle coating with a binder polymer matrix to form an integrated coating layer. This combination allows the coating to be applied as a slurry suspension that can be deposited and dried in a single step, rather than requiring separate coating and binding processes. The binder polymer (such as polyvinylidene fluoride or carboxymethyl cellulose) binds the ceramic particles together and to the separator surface, simplifying the overall fabrication process while maintaining improved wettability.

Inventive Principle:

Principle #5Merging (Combining)

4Quantity of substance

If higher areal loading or higher energy density electrodes are used, then energy and power densities are improved, but mechanical stresses and self-heating increase

Engineering Contradiction:

Improveenergy densityVSAvoidmechanical stresses

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent utilizes a porous ceramic coating structure where metal oxide particles (Al2O3, SiO2, TiO2) form an interconnected porous network on the separator surface. This porous structure provides mechanical reinforcement to withstand higher compressive stresses from high-density electrodes while maintaining high porosity (40-70%) to ensure adequate ion transport pathways. The ceramic particles act as a rigid scaffold that distributes mechanical stresses, preventing separator deformation under high areal loading conditions.

Inventive Principle:

Principle #31Porous 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 composite membrane exhibits minimal thermal shrinkage, high ionic conductivity, and superior cycle and rate performance, making it an attractive choice for electrochemical energy storage devices.

Implementation Method 1

fabricated via a non-solvent-induced phase separation process, resulting in an interconnected porous network

Methodology Applied

Scientific EffectPhase separation: Phase Change

Implementation Method 2

high ionic conductivity

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Data Source

PatentUS12580272B2Nanocomposite membrane, electrolyte-separator composite for a battery, and method of making a nanocomposite membrane

Publication Date: 2026.03.17 GEORGIA TECH RES CORP

AI summary

A nanocomposite membrane includes a polymer phase, a nanowire phase, and a pore phase. The polymer phase includes a polymer including a cyclic imide group. The nanowire phase includes metal oxide nanowires. Each of the polymer phase and the nanowire phase is uniformly distributed within at least part of the nanocomposite membrane.