Sulfide Solid Electrolyte Crystallization via Inert Atmosphere

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Solution Overview

Problem

Heat treatment during the crystallization step can deteriorate sulfide solid electrolytes, thereby worsening lithium ion conductivity, which is essential for improving the capacity and power of all-solid-state batteries using sulfide solid electrolytes.

Innovation Solution

Limiting the ambient concentration of oxygen-containing organic compounds to no more than 100 ppm during the heat treatment step in the crystallization process of sulfide solid electrolytes, along with preferred inclusion of Li, S, and P, and 10-30 mol% halogen, and conducting wet grinding with drying at reduced pressure to prevent deterioration and enhance lithium ion conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If heat treatment is performed on sulfide solid electrolytes at temperature no less than crystallization temperature to make glass ceramics, then lithium ion conductivity is improved, but sulfide solid electrolytes deteriorate due to chemical reaction with oxygen containing organic compounds

Engineering Contradiction:
Improvelithium ion conductivityVSAvoidchemical reaction with oxygen containing organic compounds
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies the inert atmosphere principle by controlling the ambient environment during heat treatment to maintain oxygen containing organic compound concentration at no more than 100 ppm. This is achieved through inert gas protection (such as nitrogen or argon atmosphere) or vacuum conditions, preventing chemical reactions between the sulfide solid electrolyte and oxygen containing organic compounds while enabling successful crystallization and improvement of lithium ion conductivity.

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

2Volume of moving object

If wet grinding by means of mechanical milling is employed for micronization, then sulfide solid electrolytes are micronized, but oxygen containing organic compounds are introduced into the system

Engineering Contradiction:
Improveparticle sizeVSAvoidoxygen containing organic compounds concentration
Core Design Contradiction:
Volume of moving objectVSQuantity of substance

Solution Approach 1:

The patent applies the extraction principle by removing oxygen containing organic compounds from the system after wet grinding. This is achieved through vacuum drying or inert gas drying processes that extract and remove the organic compounds introduced during mechanical milling, reducing their concentration to no more than 100 ppm before the heat treatment step, thereby preventing deterioration during crystallization.

Inventive Principle:
Principle #2Taking out (Extraction)

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

This method effectively prevents deterioration and significantly improves lithium ion conductivity of sulfide solid electrolytes, making them suitable for high-performance all-solid-state batteries.

Implementation Method 1

a step of crystallizing a sulfide solid electrolyte with heat treatment

Methodology Applied
Scientific EffectCrystallization: Crystallisation

Implementation Method 2

wet grinding by means of mechanical milling is employed for micronization

Methodology Applied
Scientific EffectMechanical milling: Mechanical Force

Implementation Method 3

a step of drying a specimen after the wet grinding at a reduced pressure

Methodology Applied
Scientific EffectVacuum drying: Vacuum

Data Source

PatentEP3043360B1Method for producing sulfide solid electrolyte
Publication Date: 2019.05.08 TOYOTA JIDOSHA KK
  • EP3043360B1 patent drawingFigure 1
  • EP3043360B1 patent drawingFigure 2

AI summary

Provided is a method for manufacturing a sulfide solid electrolyte which can prevent deterioration of the sulfide solid electrolyte and can improve the lithium ion conductivity. In a step of crystallizing the sulfide solid electrolyte with heat treatment, the ambient concentration of oxygen containing organic compounds is no more than 100 ppm.