Para-Aramid Battery Separator for Low Resistance and Thermal Stability

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Solution Overview

Problem

Existing separators for lithium-ion secondary batteries face challenges in achieving low resistance, high strength, and effective shielding properties while preventing thermal runaway during rapid heat generation, which is critical for applications in electric vehicles and hybrid vehicles.

Innovation Solution

A separator composed of para-aramid fibers, controlled for fiber diameter and length distribution, enhances shielding properties and reduces resistance, ensuring the battery's safety and performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If polyolefin microporous films are used as separators, then the shutdown function is provided, but heat resistance is insufficient leading to meltdown during rapid heat generation

Engineering Contradiction:
Improveshutdown functionVSAvoidheat resistance
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The patent uses composite materials by combining polyolefin base layer with a heat-resistant coating layer containing aramid fibers and heat-resistant resin. This composite structure provides both the shutdown function of polyolefin and the high heat resistance of aramid, resolving the contradiction between shutdown function and heat resistance.

Inventive Principle:
Principle #40Composite materials

2Quantity of substance

If separator thickness is reduced to meet higher capacity demand, then capacity increases, but resistance and shielding properties deteriorate

Engineering Contradiction:
Improvebattery capacityVSAvoidshielding properties
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The patent employs porous aramid fibers in the heat-resistant coating layer to create a microstructure with controlled porosity. This porous structure allows ion transport while maintaining shielding properties even in thin separators, enabling high capacity without sacrificing reliability.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The composite structure of polyolefin base layer with heat-resistant aramid coating enables the separator to maintain adequate shielding properties at reduced thickness, as the aramid coating provides enhanced structural integrity and shielding function.

Inventive Principle:
Principle #40Composite materials

3Productivity

If separator resistance is lowered for faster charging/discharging, then charging speed increases, but heat generation during abnormal conditions increases risk of meltdown

Engineering Contradiction:
Improvecharging speedVSAvoidheat generation risk
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent creates a composite separator where the polyolefin base layer enables low resistance for fast charging, while the heat-resistant aramid coating layer provides thermal stability during abnormal heat generation, thus resolving the contradiction between charging speed and safety.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentUS12567650B2Separator containing para-aramid fibers, and electrochemical device including the same
Publication Date: 2026.03.03 DUPONT SAFETY & CONSTRUCTION INC

AI summary

This separator is for electrochemical elements, is to be interposed between a pair of electrodes, and includes para-aramid fibers for holding an electrolytic solution. The separator for electrochemical elements is characterized in that the contained amount of fibers having a fiber diameter of 0.03-0.50 μm is 90 mass % or more, the proportion of the number of fibers having a fiber length not less than 0.05 mm but less than 0.20 mm is 20-30%, and the proportion of the number of fibers having a fiber length not less than 0.20 mm but less than 5.00 mm is 70-80%.