Solid Electrolyte Composition for Stable Carbon and Electrolyte Dispersion

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Solution Overview

Problem

Existing solid electrolyte compositions for all-solid state secondary batteries face challenges in achieving stable dispersion of inorganic solid electrolytes, active materials, and conductive auxiliary agents, leading to reduced conductivity and battery capacity due to aggregation and deterioration issues, particularly with carbon materials.

Innovation Solution

A solid electrolyte composition using a dispersion medium containing a ketone compound and at least one additional dispersant, such as an alcohol compound, which improves dispersion stability and prevents aggregation, allowing for high dispersibility of inorganic solid electrolytes and conductive auxiliary agents like carbon materials, thereby enhancing battery capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a non-aqueous dispersant or non-polar dispersant is used to prevent deterioration of inorganic solid electrolyte, then reliability is improved, but dispersibility of conductive auxiliary agent deteriorates

Engineering Contradiction:
Improvestability of inorganic solid electrolyteVSAvoiddispersion stability of conductive auxiliary agent
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent introduces a specific dispersant as an intermediary substance that mediates between the inorganic solid electrolyte and conductive auxiliary agent. This dispersant has functional groups that can interact with both components, enabling stable dispersion of the conductive auxiliary agent while preventing deterioration of the inorganic solid electrolyte, thus resolving the contradiction between reliability and dispersibility

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent uses a composite dispersant system combining multiple functional components. The dispersant contains both polar and non-polar characteristics, allowing it to simultaneously stabilize inorganic solid electrolyte particles and disperse hydrophobic conductive auxiliary agents like carbon materials, achieving both reliability and dispersibility requirements

Inventive Principle:
Principle #40Composite materials

2Reliability

If carbon material is used as conductive auxiliary agent, then electron conductivity is improved, but aggregation occurs reducing dispersibility

Engineering Contradiction:
Improveelectron conductivityVSAvoiddispersion stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The dispersant acts as an intermediary between carbon material particles and the liquid medium. It adsorbs onto the carbon material surface through its non-polar groups while maintaining compatibility with the polar inorganic solid electrolyte, preventing carbon aggregation and maintaining stable dispersion while preserving electron conductivity

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the chemical parameters of the dispersant to achieve optimal balance. The dispersant is designed with specific hydrophobic-hydrophilic balance and molecular structure that allows it to effectively stabilize carbon materials at specific concentrations, preventing aggregation while maintaining conductivity

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If inorganic solid electrolyte, active material, and conductive auxiliary agent are dispersed in non-polar dispersant, then dispersibility of conductive auxiliary agent is improved, but deterioration and decomposition of inorganic solid electrolyte occurs

Engineering Contradiction:
Improvedispersion stability of conductive auxiliary agentVSAvoidstability of inorganic solid electrolyte
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The patent employs a composite dispersant formulation that combines multiple functional groups and components. This composite structure allows one part to interact with and stabilize the inorganic solid electrolyte while another part effectively disperses the conductive auxiliary agent, achieving both goals simultaneously without compromise

Inventive Principle:
Principle #40Composite materials

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 proposed composition achieves improved dispersion stability and high battery capacity by maintaining the dispersoids in a stable state, preventing re-agglomeration and precipitation, and ensuring effective ion conductivity and electron conductivity in the battery.

Implementation Method 1

A slurry for forming the solid electrolyte layer is generally obtained by dispersing an inorganic solid electrolyte as an essential component for forming the layer and further a binder or the like, appropriately using various dispersants

Methodology Applied
Scientific EffectDispersion: Dispersion (of waves)

Implementation Method 2

A solid electrolyte composition using a dispersion medium containing a ketone compound and at least one additional dispersant, such as an alcohol compound, which improves dispersion stability

Methodology Applied
Scientific EffectSolvation: Solvation

Data Source

PatentEP3751642B1Solid electrolyte composition and method for producing same, solid electrolyte-containing sheet, and methods for manufacturing all-solid secondary battery electrode sheet and all-solid secondary battery
Publication Date: 2024.07.24 FUJIFILM CORP
  • EP3751642B1 patent drawingFigure 1

AI summary

Provided are a solid electrolyte composition including an inorganic solid electrolyte and a dispersion medium (A), in which the dispersion medium (A) includes a ketone compound (A1), and at least one dispersant (A2) selected from a ketone compound (A2-1) having a chemical structure different from the ketone compound (A1) or an alcohol compound (A2-2) and a method of manufacturing the same, a solid electrolyte-containing sheet, an electrode sheet for an all-solid state secondary battery, and a method of manufacturing an all-solid state secondary battery.