Sulfur-Containing Solid Electrolyte Coating for Moisture Resistance

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Solution Overview

Problem

Sulfur-containing compounds used as solid electrolytes in all-solid batteries are highly reactive with moisture and oxygen, leading to the generation of hydrogen sulfide gas, requiring handling in controlled environments with low dew points.

Innovation Solution

A sulfur-containing compound with a specific crystal structure, characterized by peaks at 2θ = 21.3°, 27.8°, and 30.8° in X-ray diffraction patterns, composed of lithium, phosphorus, sulfur, and a halogen, which suppresses hydrogen sulfide generation even in moist atmospheres.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sulfur-containing compound is used as a solid electrolyte, then high ionic conductivity is achieved, but the compound reacts with moisture to generate hydrogen sulfide gas

Engineering Contradiction:
Improveionic conductivityVSAvoidhydrogen sulfide gas generation
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies a coating layer comprising a sulfur-containing compound with specific crystal structure (argyrodite-type or related) as an intermediary between the solid electrolyte and the external environment. This coating layer acts as a barrier that prevents direct contact between moisture and the underlying solid electrolyte, thereby suppressing hydrogen sulfide gas generation while maintaining the high ionic conductivity of the core solid electrolyte material

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a composite structure consisting of a core solid electrolyte material (such as Li2S-P2S5-based compound) surrounded by a protective coating layer of sulfur-containing compound with specific crystal structure. This composite material design combines the high ionic conductivity of the core material with the moisture resistance of the coating layer, resolving the contradiction between performance and stability

Inventive Principle:
Principle #40Composite materials

2Reliability

If a sulfur-containing compound is used as a solid electrolyte, then high ionic conductivity is achieved, but handling in controlled environments is required

Engineering Contradiction:
Improveionic conductivityVSAvoidhandling ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The protective coating layer serves as an intermediary that shields the solid electrolyte from environmental moisture, eliminating the need for controlled environment handling. The coating layer allows the solid electrolyte to be handled in standard atmospheric conditions while maintaining its high ionic conductivity performance

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates an inert protective environment through the coating layer that prevents harmful reactions between the solid electrolyte and atmospheric moisture. This coating-induced inert environment enables easy handling without requiring external controlled environment facilities, resolving the contradiction between performance and operational convenience

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 compound effectively prevents hydrogen sulfide gas formation, enhancing the safety and handling of solid electrolytes, allowing for their use in standard environments without the need for specialized dry rooms.

Implementation Method 1

A sulfur-containing compound with a specific crystal structure, characterized by peaks at 2θ = 21.3°, 27.8°, and 30.8° in X-ray diffraction patterns

Methodology Applied
Scientific EffectCrystal structure:

Implementation Method 2

characterized by peaks at 2θ = 21.3°, 27.8°, and 30.8° in X-ray diffraction patterns

Methodology Applied
Scientific EffectX-ray diffraction: X-Ray

Implementation Method 3

characterized by peaks at 2θ = 21.3°, 27.8°, and 30.8° in X-ray diffraction patterns

Methodology Applied
Scientific EffectDiffraction: Diffraction

Data Source

PatentEP3766832B1Sulfur-containing compound, solid electrolyte, and battery
Publication Date: 2022.12.28 MITSUI MINING & SMELTING CO LTD
  • EP3766832B1 patent drawingFigure 1~3
  • EP3766832B1 patent drawingFigure 4~5
  • EP3766832B1 patent drawing

AI summary

Provided is a novel sulfur-containing compound containing a lithium (Li) element, a phosphorus (P) element, a sulfur (S) element, and a halogen (X) element, which can be suitably used as, for example, a solid electrolyte, and is able to suppress the generation of a hydrogen sulfide gas even when exposed to moisture in the atmosphere. The sulfur-containing compound contains a lithium (Li) element, a phosphorus (P) element, a sulfur (S) element, and a halogen (X) element, and has a peak at each position of 2θ = 21.3° ± 1.0°, 27.8° ± 1.0°, and 30.8° ± 0.5° in an X-ray diffraction pattern measured by an X-ray diffraction apparatus (XRD) using CuKα1 rays.