Eutectic Electrolyte for Lithium Ion Battery Safety

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Solution Overview

Problem

Lithium ion secondary batteries face safety issues due to the volatility and flammability of organic solvents in their electrolytes, and existing ionic liquids are not suitable for practical application due to reduced battery capacity and high production costs.

Innovation Solution

A eutectic mixture comprising an amide group-containing compound with an electron donating group (EDG) introduced at the N-position and an ionizable lithium salt is used as the electrolyte, providing improved thermal and chemical stability, flame retardancy, and reduced reduction potential, thus enhancing safety and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If organic solvent is used in the electrolyte, then the battery provides high drive voltage and energy density, but the battery suffers from safety problems due to volatility and flammability

Engineering Contradiction:

Improvedrive voltageVSAvoidflammability

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters of the electrolyte by introducing amide group-containing compounds with electron donating groups at N-position, which modifies the reduction potential and electrochemical stability window to achieve both high power and safety

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite electrolyte system combining amide group-containing compounds with ionizable lithium salts in a eutectic mixture, achieving synergistic effects that provide both high energy density and flame retardancy

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If imidazolium-based ionic liquid is used as electrolyte, then the safety is improved, but the battery capacity drops significantly during repeated charge/discharge cycles

Engineering Contradiction:

ImprovesafetyVSAvoidbattery capacity

Core Design Contradiction:

Object-affected harmful factorsVSDuration of action of moving object

Solution Approach 1:

The patent modifies the electrolyte composition by using amide group-containing compounds with specific electron donating groups that adjust the reduction potential to be lower than lithium ion redox potential, preventing ionic liquid reduction and maintaining stable battery capacity over cycles while ensuring safety

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If imidazolium-based ionic liquid is used as electrolyte, then the safety is improved, but the production cost increases and filtration becomes complicated

Engineering Contradiction:

ImprovesafetyVSAvoidproduction cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent employs amide group-containing compounds that are cheaper and easier to produce than imidazolium-based ionic liquids, simplifying manufacturing processes while maintaining safety benefits

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the chemical structure parameters to use amide groups with electron donating groups, which are simpler to synthesize and handle compared to imidazolium structures, reducing production complexity and cost

Inventive Principle:

Principle #35Parameter changes

4Reliability

If eutectic mixture with EDG at N-position is used as electrolyte, then the reduction stability is improved and safety is ensured, but the device complexity increases

Engineering Contradiction:

Improvereduction stabilityVSAvoidelectrolyte composition

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces electron donating groups at the specific N-position of amide groups, creating localized chemical modifications that provide the desired electrochemical properties without requiring complete structural redesign of the entire electrolyte system

Inventive Principle:

Principle #3Local quality

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 mixture ensures the safety and stability of lithium ion secondary batteries by lowering the reduction potential and expanding the electrochemical stability window, allowing for the use of anodes with lower reduction potentials, thereby improving battery performance and capacity.

Implementation Method 1

the at least one EDG introduced into the N-position of the amide group-containing compound lowers the reduction potential of the eutectic mixture

Methodology Applied

Scientific EffectElectron donating group effect:

Implementation Method 2

an electrolyte transferring lithium ions between the cathode and the anode

Methodology Applied

Scientific EffectIon transfer: Electrolysis

Data Source

PatentUS8808924B2Electrolyte comprising eutectic mixture and secondary battery using the same

Publication Date: 2014.08.19 LG ENERGY SOLUTION LTD

AI summary

Disclosed is an electrolyte for a secondary battery, comprising an eutectic mixture consisting of: (a) am amide group-containing compound with at least one EDG introduced into the N-position thereof; and (b) an ionizable lithium salt. Also, provided are a secondary battery comprising such an electrolyte, and a method of adjusting an electrochemical stability window of an eutectic mixture consisting of an amide group-containing compound and a lithium salt by regulating electron donating properties of at least one substituent group introduced into the N-position of the amide group-containing compound.