Granular Sulfide Solid Electrolyte for Moisture-Stable Li Ion Conductivity

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Solution Overview

Problem

The Li ion conductivity of sulfide solid electrolytes is decreased due to moisture exposure.

Innovation Solution

A sulfide solid electrolyte with a granular shape and a crystal portion oriented along its inner surface is developed, comprising a Li, P, S, and O composition, which suppresses the decrease in Li ion conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sulfide solid electrolyte is used in an all solid state battery, then the safety is improved compared to liquid batteries, but the Li ion conductivity decreases due to moisture exposure

Engineering Contradiction:

ImprovesafetyVSAvoidLi ion conductivity decrease due to moisture

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by creating a crystalline surface layer specifically on the inner surface of the sulfide solid electrolyte particles. This surface layer has different structural properties (crystalline) compared to the bulk material, providing localized protection against moisture while maintaining the overall sulfide solid electrolyte composition and properties needed for battery operation

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent creates a composite structure where a crystalline phase forms on the surface of the sulfide solid electrolyte particles. This composite approach combines the protective properties of the crystalline surface layer with the ionic conductivity properties of the sulfide solid electrolyte bulk, achieving both moisture resistance and maintained Li ion conductivity

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS12374716B2Sulfide solid electrolyte and all solid state battery

Publication Date: 2025.07.29 TOYOTA JIDOSHA KK

AI summary

A main object of the present disclosure is to provide a sulfide solid electrolyte capable of suppressing a decrease in Li ion conductivity due to moisture. The present disclosure achieves the object by providing a sulfide solid electrolyte comprising a Li element, a P element, a S element and an O element, and having a granular shape, and including a crystal portion oriented along the granular shape, on an inner surface of the sulfide solid electrolyte.