Plastic Crystal Electrolyte for Flexible Battery Safety

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Solution Overview

Problem

Existing secondary batteries face challenges with liquid electrolytes due to degradation of electrode materials, solvent evaporation, safety risks, and mechanical weaknesses, while solid polymer electrolytes offer poor performance and gel polymer electrolytes have low ionic conductivity and mechanical issues.

Innovation Solution

A plastic crystal matrix electrolyte doped with an ionic salt and a crosslinked polymer structure, featuring a linear polymer with a weight average molecular weight of 100 to 5,000 and one functional group, which enhances both ionic conductivity and mechanical strength, eliminating the need for solvents and simplifying the preparation process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If liquid electrolytes are used, then high ionic conductivity is achieved, but safety risks and mechanical weaknesses occur

Engineering Contradiction:
Improveionic conductivityVSAvoidsafety risks
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent uses a composite structure combining plastic crystal matrix (for ionic conductivity) with crosslinked polymer network (for mechanical strength and safety). This composite approach allows the electrolyte to simultaneously achieve high ionic conductivity comparable to liquid electrolytes while obtaining the mechanical strength and thermal stability of solid electrolytes, eliminating the safety risks associated with liquid electrolytes.

Inventive Principle:
Principle #40Composite materials

2Object-affected harmful factors

If solid polymer electrolytes are used, then safety is improved, but performance deteriorates

Engineering Contradiction:
ImprovesafetyVSAvoidperformance
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent changes the physical state parameter of the polymer electrolyte from conventional solid gel state to plastic crystal state. This parameter change enables the electrolyte to maintain the safety advantages of solid electrolytes while achieving ionic conductivity levels comparable to liquid electrolytes, thus improving performance without sacrificing safety.

Inventive Principle:
Principle #35Parameter changes

3Strength

If gel polymer electrolytes are used, then mechanical strength is improved, but ionic conductivity decreases

Engineering Contradiction:
Improvemechanical strengthVSAvoidionic conductivity
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent utilizes the phase transition of the polymer electrolyte to a plastic crystal state, where the material exhibits both solid-like mechanical properties and liquid-like ionic conductivity. This phase transition allows the electrolyte to overcome the trade-off between mechanical strength and ionic conductivity that plagues gel polymer electrolytes.

Inventive Principle:
Principle #36Phase transitions

4Strength

If linear polymer matrices are added to improve mechanical strength, then mechanical properties are enhanced, but the need for separators remains and processing becomes complicated

Engineering Contradiction:
Improvemechanical strengthVSAvoidprocessing complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent merges the functions of mechanical reinforcement and separator into a single integrated structure. The crosslinked polymer network simultaneously provides mechanical strength to the electrolyte and acts as a separator, eliminating the need for separate separator components and simplifying the overall device structure and processing.

Inventive Principle:
Principle #5Merging (Combining)

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 electrolyte achieves high ionic conductivity comparable to liquid electrolytes and mechanical strength similar to solid electrolytes, ensuring thermal stability and flexibility, making it suitable for flexible battery shapes without the need for separators.

Implementation Method 1

a plastic crystal matrix electrolyte doped with an ionic salt

Methodology Applied
Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

a crosslinked polymer structure having a linear polymer as a side chain chemically bonded thereto

Methodology Applied
Scientific EffectCrosslinking: Chemical Bonding

Data Source

PatentEP2667443B1Electrolyte for an electrochemical device, method for manufacturing same, and electrochemical device including same
Publication Date: 2016.08.31 LG CHEM LTD
  • EP2667443B1 patent drawingFigure 1~2
  • EP2667443B1 patent drawingFigure 3~4

AI summary

Disclosed is a solid electrolyte for an electrochemical device. The solid electrolyte includes a composite of a plastic crystal matrix electrolyte doped with an ionic salt and a crosslinked polymer structure having a linear polymer as a side chain chemically bonded thereto. The linear polymer has a weight average molecular weight of 100 to 5,000 and one functional group. The electrolyte has high ionic conductivity comparable to that of a liquid electrolyte due to the use of the plastic crystal, and high mechanical strength comparable to that of a solid electrolyte due to the introduction of the crosslinked polymer structure. Further disclosed is method for preparing the solid electrolyte. The method does not essentially require the use of a solvent, eliminating the need for drying. Therefore, the electrolyte can be prepared in a simple manner. The electrolyte is suitable for use in a cable-type battery whose shape is easy to change due to its high ionic conductivity and high mechanical strength comparable to that of a solid electrolyte.