Fluorinated Aromatic Electrolyte for Safer Lithium Secondary Batteries

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Solution Overview

Problem

Lithium secondary batteries face safety concerns due to the flammability and volatility of carbonate-based organic solvents, leading to thermal runaway and dendrite formation, which compromises battery energy density and safety.

Innovation Solution

An electrolyte composition for lithium secondary batteries using an aromatic solvent with fluorine, such as 2,3-difluorotoluene, and an ether solvent, which suppresses side reactions and provides flame retardancy by forming a stable protective film on the electrode surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If carbonate-based organic solvents are used as electrolytes to achieve high battery operating voltage and energy density, then the battery energy density is improved, but the battery safety deteriorates due to flammability and thermal runaway

Engineering Contradiction:

Improvebattery energy densityVSAvoidbattery safety

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the electrolyte by replacing carbonate-based solvents with fluorinated aromatic solvents and cyclic carbonates. This parameter change reduces flammability and improves safety while maintaining the high voltage stability needed for energy density, thus resolving the contradiction between energy density and safety

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite electrolyte system combining fluorinated aromatic solvents (like 2,3-difluorotoluene) with cyclic carbonate solvents (like EC and PC). This composite approach leverages the flame-retardant properties of fluorinated compounds while utilizing the high dielectric constant and ionic conductivity of cyclic carbonates, achieving both safety and energy density requirements

Inventive Principle:

Principle #40Composite materials

2Power

If carbonate-based organic solvents are used at high temperatures to rapidly increase battery temperature, then the battery output is improved, but thermal runaway occurs due to combustion reaction with electrode material

Engineering Contradiction:

Improvebattery outputVSAvoidthermal runaway

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The patent converts the potential harm of high-temperature operation into a benefit by using fluorinated aromatic solvents that are inherently flame-retardant and thermally stable. These solvents can withstand high temperatures without combusting, allowing the battery to deliver high output power even under thermal stress without risking thermal runaway

Inventive Principle:

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

3Temperature

If carbonate-based organic solvents are used as electrolytes, then the battery operating voltage is improved, but dendrite formation occurs leading to side reactions with lithium metal

Engineering Contradiction:

Improvebattery operating voltageVSAvoiddendrite formation

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent introduces fluorinated aromatic solvents as intermediary substances that mediate between the lithium metal electrode and the electrolyte. These solvents form stable protective films on the lithium surface that prevent direct contact and side reactions, while still allowing ionic transport, thus eliminating dendrite formation while maintaining high operating voltage

Inventive Principle:

Principle #24Intermediary (Mediator)

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 composition enhances safety by reducing flammability, improves life characteristics, and maintains excellent output characteristics through improved ionic conductivity and reduced cell resistance.

Implementation Method 1

An electrolyte composition for a lithium secondary battery includes a lithium salt and an organic solvent, in which the organic solvent includes an aromatic solvent of Chemical Formula 1 and an ether solvent... the aromatic solvent may provide flame retardancy to an electrolyte while suppressing side reactions between a negative electrode and the electrolyte

Methodology Applied

Scientific EffectFlame retardancy:

Implementation Method 2

the organic solvent includes an aromatic solvent of the following Chemical Formula 1 and an ether solvent... in which the organic solvent includes an aromatic solvent of Chemical Formula 1 and an ether solvent

Methodology Applied

Scientific EffectSolvation: Solvation

Implementation Method 3

Methodology Applied

Scientific EffectIonic conductivity: Conduction (electrical)

Data Source

PatentUS20260058209A1Electrolyte composition for lithium secondary battery and lithium secondary battery containing the same

Publication Date: 2026.02.26 HYUNDAI MOTOR CO LTD

AI summary

An electrolyte composition for lithium secondary batteries includes a lithium salt and an organic solvent. The organic solvent includes an aromatic solvent with fluorinated toluene derivatives (such as 2,3-difluorotoluene) and an ether solvent. The lithium salt can include compounds like Li(CF3SO2)2N, Li(SO2F)2N, LiPF6, and others. The aromatic solvent is present at about 30-90 vol % of the electrolyte, and the lithium salt molarity ranges from 0.1 to 3.0 M. This composition improves battery performance by enhancing stability, conductivity, and compatibility with lithium metal or lithium-ion electrodes, making it suitable for high-energy-density applications in lithium secondary batteries.