Polyimide Separator Manufacturing via Alkaline Etching

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Solution Overview

Problem

Conventional lithium battery separators lack high-temperature resistance, which can lead to short-circuiting and potential explosions when exposed to elevated temperatures, limiting their application in modern electronic devices that require miniaturization and high energy density.

Innovation Solution

A separator manufacturing method involving the mixing and solidification of polyimide precursor polymers, followed by an alkaline liquid etching process to create irregular holes, and the application of ceramic-polymer films for enhanced thermal stability and ion conductivity, eliminating the need for additional micro-hole formation processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If conventional polyethylene or polypropylene materials are used for separator body, then manufacturing process is simple, but high-temperature resistance is insufficient leading to short-circuiting and potential explosions

Engineering Contradiction:

Improvehigh-temperature resistanceVSAvoidsafety against short-circuiting and explosion

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent uses polyimide as the separator body material, which is a high-temperature resistant polymer that maintains structural integrity at temperatures where conventional polyethylene or polypropylene would melt and fail. This composite material approach resolves the contradiction by providing both the required temperature resistance and safety reliability simultaneously.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the material parameter from conventional low-temperature polymers to high-temperature resistant polyimide, fundamentally altering the thermal properties of the separator. This parameter change enables the separator to withstand higher temperatures without structural failure, thereby improving both temperature resistance and safety reliability.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If additional micro-hole formation processes are used to improve ion conductivity, then ion migration path is enhanced, but manufacturing complexity and cost increase

Engineering Contradiction:

Improveion conductivityVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs a self-organizing phase separation mechanism during the casting process where the polymer matrix naturally forms interconnected porous structures without requiring additional drilling or etching steps. This self-service approach allows the material to automatically create the necessary ion migration pathways, achieving high ion conductivity while maintaining simple manufacturing processes.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent utilizes inherently porous polyimide structures formed through controlled phase separation during manufacturing. These porous materials provide continuous ion migration pathways throughout the separator body, enhancing ion conductivity without requiring complex post-processing steps to create holes or channels.

Inventive Principle:

Principle #31Porous materials

3Productivity

If separator structure is optimized for high ion conductivity, then battery performance is improved, but thermal stability may be compromised

Engineering Contradiction:

Improveion migration efficiencyVSAvoidthermal stability

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The patent creates a composite structure combining polyimide matrix with controlled porous morphology, where the polyimide provides thermal stability while the porous network enables efficient ion migration. This composite approach allows simultaneous optimization of both thermal stability and ion conductivity that would be difficult to achieve with conventional materials.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent implements local quality optimization by creating regions of different porosity and density within the separator structure. Areas with higher porosity facilitate ion migration, while regions with denser polyimide structure provide thermal stability. This spatial variation in material properties allows the separator to simultaneously achieve high ion conductivity and maintain thermal stability.

Inventive Principle:

Principle #3Local quality

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 separator exhibits improved high-temperature resistance, increased manufacturing efficiency, and enhanced thermal stability, preventing short-circuiting and ensuring the safety and performance of lithium battery elements.

Implementation Method 1

removing the first material by an alkaline liquid etching process to form an separator body, so that the separator body has a plurality of irregular holes formed corresponding to the removed first material

Methodology Applied

Scientific EffectAlkaline liquid etching:

Implementation Method 2

application of ceramic-polymer films for enhanced thermal stability and ion conductivity

Methodology Applied

Scientific EffectThermal stability:

Data Source

PatentUS8574769B2Manufacturing method for polyimide separator

Publication Date: 2013.11.05 PROLOGIUM TECHNOLOGY CO LTD

AI summary

A separator includes a separator body and a first film. The separator body is formed by mixing and solidifying a first material and a second material and then removing the first material by an alkaline liquid etching process. The separator body has a plurality of irregular holes formed corresponding to the removed first material. The first film is disposed on one side of the separator body.