Gel Polymer Electrolyte Ionic Liquid Flame Retardancy

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Solution Overview

Problem

Lithium secondary batteries face challenges with the instability of liquid electrolyte solutions at high temperatures and voltages, leading to oxidative decomposition and reduced capacity, while gel polymer electrolytes lack adequate flame retardancy.

Innovation Solution

A gel polymer electrolyte composition is developed, including a lithium salt, ionic liquid, polymerization initiator, and oligomer, which improves high-temperature stability and flame retardancy by replacing non-aqueous organic solvents with an ionic liquid, enhancing oxidation resistance and lithium ion mobility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a liquid electrolyte solution is used to increase energy density and driving voltage, then the battery capacity is improved, but the electrolyte solution becomes unstable and undergoes oxidative decomposition at high voltage and temperature

Engineering Contradiction:

Improvebattery capacityVSAvoidelectrolyte stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the electrolyte by incorporating ionic liquids with specific molecular structures (containing imidazolium, pyridinium, or ammonium cations with particular substituent groups) to achieve both high voltage stability and maintained battery capacity. This parameter change allows the electrolyte to withstand higher voltages without decomposition while preserving ion conductivity for capacity.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a gel polymer electrolyte is used to improve stability and prevent leakage, then the battery reliability is improved, but flame retardancy is insufficient due to poor oxidation resistance

Engineering Contradiction:

Improvebattery stabilityVSAvoidflame retardancy

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent creates a composite gel polymer electrolyte system that combines the structural benefits of gel polymers (stability, leakage prevention) with the fire-resistant properties of specifically designed ionic liquids. The composite structure integrates the polymer matrix with ionic liquid components that possess inherent flame retardancy, achieving both reliability and safety.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent converts the potential harm of organic solvents (flammability) into a benefit by selecting ionic liquids that inherently possess both the desired electrochemical stability and fire resistance. The ionic liquid components, which could be seen as replacing traditional organic solvents, actually provide improved safety characteristics while maintaining functional performance.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Quantity of substance

If the driving voltage is increased to improve energy density, then the battery capacity is improved, but the electrolyte solution is oxidized and decomposed forming unstable films on the positive electrode

Engineering Contradiction:

Improvebattery capacityVSAvoidfilm stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent modifies the electrolyte composition parameters by incorporating ionic liquids with specific functional groups and molecular structures that are resistant to oxidation at high voltages. These parameter changes enable the formation of stable protective films on the positive electrode even at elevated driving voltages, preventing the decomposition and instability issues associated with conventional electrolytes.

Inventive Principle:

Principle #35Parameter changes

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 solution provides improved high-temperature storage stability, oxidation resistance, and flame retardancy, maintaining capacity and preventing ignition in lithium secondary batteries.

Implementation Method 1

enhancing oxidation resistance and lithium ion mobility

Methodology Applied

Scientific EffectOxidation resistance: Oxidation

Implementation Method 2

a process is repeated in which lithium ions of the positive electrode are intercalated into and deintercalated from the negative electrode

Methodology Applied

Scientific EffectIntercalation: Absorption (physical)

Implementation Method 3

a gel polymer electrolyte composition for a lithium secondary battery which includes a lithium salt, an ionic liquid, a polymerization initiator, and an oligomer

Methodology Applied

Scientific EffectPolymerization: Chemical Bonding

Data Source

PatentUS11316194B2Gel polymer electrolyte composition, gel polymer electrolyte prepared thereby, and lithium secondary battery including the gel polymer electrolyte

Publication Date: 2022.04.26 LG ENERGY SOLUTION LTD

AI summary

The present invention relates to a gel polymer electrolyte composition and a lithium secondary battery including the same, and particularly, to a gel polymer electrolyte composition, in which flame retardancy is improved by including an ionic liquid, instead of a non-aqueous organic solvent, as well as a lithium salt, a polymerization initiator, and an oligomer having a specific structure, and a lithium secondary battery in which high-temperature stability is improved by including the same.