Chiral Ionic Liquid Electrolyte for Low-Temperature Battery Safety

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Solution Overview

Problem

Conventional lithium secondary batteries using organic solvents as electrolytes are unsafe due to flammability and have reduced ion conductivity at low temperatures, limiting their performance.

Innovation Solution

An ionic liquid with a chiral cation having an asymmetric carbon atom and specific substituents is used as the electrolyte, maintaining liquid state over a wide temperature range and enhancing ion conductivity at low temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional organic solvents are used as electrolytes, then ion conductivity at room temperature is maintained, but safety deteriorates due to flammability and volatility

Engineering Contradiction:

ImprovesafetyVSAvoidflammability

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the fundamental parameter of the electrolyte from conventional organic solvents to ionic liquids, which have inherently different physical and chemical properties including non-flammability and non-volatility, while maintaining ionic conductivity through specific molecular structure design

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite electrolyte system by combining ionic liquid with specific cation structures (containing asymmetric carbon atoms) and counterions, achieving a material that integrates both safety (non-flammability) and functional performance (ion conductivity)

Inventive Principle:

Principle #40Composite materials

2Reliability

If conventional organic solvents are used as electrolytes, then ion conductivity is maintained at room temperature, but ion conductivity deteriorates at low temperatures

Engineering Contradiction:

Improveion conductivityVSAvoidlow temperature performance

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent modifies the electrolyte's physical state parameters by using ionic liquids with specific melting points and viscosity characteristics, enabling the electrolyte to remain in liquid state and maintain ionic conductivity across a wide temperature range including low temperatures

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs chiral cations with asymmetric carbon atoms that create specific molecular arrangements and interactions, copying the beneficial low-temperature fluidity properties while maintaining the ionic conductivity necessary for battery operation

Inventive Principle:

Principle #26Copying

3Temperature

If ionic liquid with chiral cation is used as electrolyte, then low temperature ion conductivity is improved, but device complexity increases due to specific structural requirements

Engineering Contradiction:

Improvelow temperature ion conductivityVSAvoidstructural complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The patent introduces asymmetry locally at the carbon atom position within the cation structure, creating a chiral center that influences the overall molecular arrangement and low-temperature properties, while the rest of the molecular structure remains relatively simple and manageable

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent deliberately introduces asymmetric carbon atoms with specific substituents into the cation structure, creating chiral ionic liquids that exhibit improved low-temperature fluidity and ionic conductivity while maintaining controllable molecular complexity

Inventive Principle:

Principle #4Asymmetry

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 ionic liquid-based electrolyte provides increased ion conductivity at low temperatures, improving battery performance without compromising room temperature performance and enhancing safety by being non-flammable.

Implementation Method 1

the electrolyte is provided with a lower melting point than the ionic liquid; instead it rather vitrifies

Methodology Applied

Scientific EffectVitrification: Vitrification

Implementation Method 2

when the substituents bonded to the asymmetric carbon atom are small, the ionic liquid is low viscosity and thus the ion conductivity of the ionic liquid can be increased

Methodology Applied

Scientific EffectViscosity reduction:

Implementation Method 3

it is generally nonflammable and nonvolatile

Methodology Applied

Scientific EffectNon-flammability:

Implementation Method 4

it is generally nonflammable and nonvolatile

Methodology Applied

Scientific EffectNon-volatility:

Implementation Method 5

a lithium ion (Li+) produced by the formula (I) is transferred through the electrolyte sandwiched between the negative and positive electrodes from the negative electrode side to the positive electrode side

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Data Source

PatentUS9130240B2Ionic liquid, lithium secondary battery electrolyte comprising the ionic liquid, and lithium secondary battery comprising the electrolyte

Publication Date: 2015.09.08 TOYOTA JIDOSHA KK

AI summary

The object of the present invention is to provide an ionic liquid having a chiral center in the structure of a cation contained therein, a lithium secondary battery electrolyte includes the ionic liquid, and a lithium secondary battery including the electrolyte