Lithium-Ion Conducting Electrolyte Composition for Thermal Stability

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Solution Overview

Problem

Conventional lithium ion conducting materials face limitations in lithium ion conductive properties and thermal stability.

Innovation Solution

A lithium ion conducting material comprising cyclic carbonate as a solvent and lithium amide salt, with a molar ratio of the lithium amide salt to cyclic carbonate between 0.25 and 0.33, and optionally including a sulfide solid electrolyte, to enhance thermal stability and lithium ion conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional lithium ion conducting materials are used, then the materials can conduct lithium ions, but the lithium ion conductive properties and thermal stability are insufficient

Engineering Contradiction:
Improvethermal stabilityVSAvoidlithium ion conductive properties
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies parameter changes by precisely controlling the molar ratio of lithium amide salt to cyclic carbonate within 0.25-0.33, and selecting specific lithium amide salts (lithium bisfluorosulfonylamide or lithium bistrifluoromethanesulfonylamide) to achieve optimal balance between lithium ion conductivity and thermal stability. This quantitative parameter optimization resolves the contradiction by finding the precise compositional range where both properties are satisfied.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite electrolyte system by combining cyclic carbonate solvent with lithium amide salt in specific proportions, forming a new material composition that exhibits both excellent lithium ion conductive properties and enhanced thermal stability. The composite nature of this electrolyte solution allows simultaneous achievement of properties that individual components cannot provide alone.

Inventive Principle:
Principle #40Composite materials

2Reliability

If sulfide solid electrolyte is added to enhance thermal stability, then thermal stability improves, but reactivity with the sulfide solid electrolyte increases

Engineering Contradiction:
Improvethermal stabilityVSAvoidreactivity with sulfide solid electrolyte
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The cyclic carbonate containing lithium amide salt acts as an intermediary between the electrodes and the sulfide solid electrolyte. This intermediate electrolyte layer provides the necessary ionic conductivity while forming a protective interface that reduces direct contact and harmful reactions between the sulfide solid electrolyte and other battery components, thus resolving the contradiction between thermal stability enhancement and reactivity reduction.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The lithium amide salt in cyclic carbonate creates a chemically stable environment that protects the sulfide solid electrolyte from unwanted reactions. The specific chemical composition acts as an inert barrier, maintaining thermal stability while minimizing reactivity, allowing the sulfide solid electrolyte to function effectively without degradation.

Inventive Principle:
Principle #39Inert atmosphere (Inert environment)

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 achieves excellent lithium ion conductive properties and thermal stability, while minimizing reactivity with the sulfide solid electrolyte, thereby improving the performance of lithium ion secondary batteries.

Implementation Method 1

a lithium ion conducting material, comprising a cyclic carbonate as a solvent, and a lithium amide salt dissolved in the cyclic carbonate

Methodology Applied
Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

a lithium amide salt dissolved in the cyclic carbonate

Methodology Applied
Scientific EffectSolvation: Solvation

Data Source

PatentEP4246640A1Lithium ion conducting material and lithium ion secondary battery
Publication Date: 2023.09.20 TOYOTA JIDOSHA KK
  • EP4246640A1 patent drawingFigure 1
  • EP4246640A1 patent drawingFigure 2~3
  • EP4246640A1 patent drawingFigure 4

AI summary

Disclosed is a lithium ion conducting material having excellent lithium ion conductive properties and thermal stability. The lithium ion conducting material of the present disclosure comprises a cyclic carbonate as a solvent and a lithium amide salt dissolved in the cyclic carbonate, wherein a molar ratio of the lithium amide salt to the cyclic carbonate is greater than 0.25 and 0.33 or less.