Single-Ion Eutectic Polymer Electrolytes for Room-Temperature Conductivity

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Solution Overview

Problem

Existing polymeric solid electrolytes, particularly those based on poly(ethylene oxide) derivatives, suffer from low ion transport number and ionic conductivity, especially at room temperature, and conventional eutectogels with conductive liquid phases face safety issues and incomplete unipolar conductivity.

Innovation Solution

A unipolar ionic conductivity eutectic polymeric electrolyte, or single-ion eutectogel, is developed using a specific combination of ethylenically polymerizable monomers with anionic groups and hydrogen bond donors in a controlled molar ratio, forming a polymer matrix with alkali metal cations, enhancing ionic conductivity and transport number to 1.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If poly(ethylene oxide) derivatives are used as polymer matrices, then the ability to complex alkali metal cations is improved, but the ion transport number and ionic conductivity deteriorate

Engineering Contradiction:

Improveability to complex cationsVSAvoidion transport number

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent inverts the conventional electrolyte structure by making the polymer matrix itself the source of mobile ions through carboxylate groups, rather than relying on dissolved salts. This inversion allows the polymer backbone to directly provide both structural support and ionic conductivity, resolving the contradiction between complexation ability and ion transport number.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent creates a composite structure combining polyether chains with carboxylate groups to form a dual-function material that simultaneously provides cation complexation sites and mobile ionic groups, achieving both high adaptability and high ion transport number in a single integrated system.

Inventive Principle:

Principle #40Composite materials

2Temperature

If poly(ethylene oxide) is used as polymer matrix, then the glass transition temperature is improved (low Tg), but the ionic conductivity deteriorates below melting point due to crystallinity

Engineering Contradiction:

Improveglass transition temperatureVSAvoidionic conductivity

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent changes the chemical parameters of the polymer matrix by introducing carboxylate groups, which alter the physical properties to reduce crystallinity and maintain amorphous structure at room temperature, thereby preserving ionic conductivity without requiring liquid phases or plasticizers.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If conductive liquid phase is added to improve ionic conductivity, then the ionic conductivity is improved, but the safety and environmental criteria deteriorate

Engineering Contradiction:

Improveionic conductivityVSAvoidsafety and environmental criteria

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts and eliminates the harmful conductive liquid phase from the electrolyte system, replacing it with a solid polymer matrix that provides intrinsic ionic conductivity through carboxylate groups, thereby maintaining performance while improving safety and environmental criteria.

Inventive Principle:

Principle #2Taking out (Extraction)

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 eutectic polymeric electrolyte achieves ionic conductivity greater than 6.4·10⁻⁵ S.cm⁻¹ and a transport number of 1 at 30°C, providing improved safety and ease of synthesis while maintaining homogeneity.

Implementation Method 1

at least one polymer whose main chain is formed from monomers, M, in C2 to C20 ethylenically polymerizable

Methodology Applied

Scientific EffectPolymerization:

Implementation Method 2

The transport of the proton or alkali cation, in particular lithium, sodium or potassium cation, between the cathode and the anode, is ensured by an ionically conductive electrolyte

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 3

a specific combination of ethylenically polymerizable monomers with anionic groups and hydrogen bond donors in a controlled molar ratio

Methodology Applied

Scientific EffectHydrogen bonding:

Data Source

PatentEP4667501A1Deep eutectic polymer electrolytes with unipolar ion conductivity

Publication Date: 2025.12.24 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

Figure 1~2
Figure 3~4

AI summary

A unipolar ionic conductivity eutectic polymeric electrolyte, also called SI PDEE, comprising: - at least one polymer whose main chain is formed from monomers, M, in C2 to C20 ethylenically polymerizable with at least one, and preferably several, monomeric units of said main chain bearing at least one anionic group called SI-, - at least one hydrogen bond donor species, called HBD, in an SI-:HBD molar ratio varying from 1:0.5 to 1:15, in particular from 1:1 to 1:15; and - at least one alkali metal cation, X+.