Chalcogen-Coated Sulfide Solid Electrolyte for Stable Cathode Interfaces

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Solution Overview

Problem

Sulfide-based solid electrolytes in all-solid-state batteries face interface instability and reactivity issues with positive electrode materials, leading to poor ionic conductivity and increased process costs due to surface treatment requirements, hindering their commercialization.

Innovation Solution

A surface-modified composite solid electrolyte is developed by forming a coating film containing a functional group derived from a chalcogen-based compound on the surface of sulfide-based solid electrolyte particles, enhancing chemical and electrochemical stability at the interface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sulfide-based solid electrolyte is used to achieve high lithium ionic conductivity and excellent flexibility, then the electrochemical performance is improved, but the interface stability deteriorates due to high reactivity with moisture and positive electrode active material

Engineering Contradiction:

Improveelectrochemical performanceVSAvoidinterface stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

An organic compound coating layer is introduced as an intermediary between the sulfide-based solid electrolyte and the positive electrode active material. This coating layer acts as a mediator that prevents direct contact and harmful reactions between the electrolyte and electrode materials, while still allowing lithium ion transport. The coating layer specifically suppresses the formation of P2Sx and sulfide bonds at the interface, resolving the interface stability issue without compromising the high ionic conductivity of the bulk electrolyte.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention creates a composite structure consisting of the sulfide-based solid electrolyte core and an organic compound coating shell. This composite material combines the advantages of the sulfide electrolyte (high ionic conductivity and flexibility) with the protective properties of the organic coating (chemical stability and interface protection), achieving both high electrochemical performance and improved interface stability.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If the surface of the positive electrode active material is coated with a protective film to improve interface stability, then the interface resistance is reduced, but the process cost increases due to additional surface treatment steps

Engineering Contradiction:

Improveinterface stabilityVSAvoidprocess cost

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

Instead of coating the positive electrode active material with a protective film (the conventional approach), the invention inverts the approach by coating the sulfide-based solid electrolyte surface with an organic compound. This inversion simplifies the manufacturing process because the electrolyte coating can be applied directly during electrolyte synthesis or processing, eliminating the need for separate electrode surface treatment steps and reducing overall process cost.

Inventive Principle:

Principle #13The other way round (Inversion)

3Stability of the object's composition

If a coating film is formed on the sulfide-based solid electrolyte surface to suppress side reactions, then the chemical and electrochemical stability is improved, but the manufacturing complexity increases

Engineering Contradiction:

Improvechemical and electrochemical stabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The invention employs parameter changes in the form of selecting specific organic compounds with particular functional groups (such as carboxylic acid, hydroxyl, or amine groups) that have affinity for sulfide surfaces. By adjusting the chemical parameters of the coating material and controlling coating conditions (temperature, time, concentration), a stable coating is formed through simple processes like solution immersion or vapor deposition, avoiding complex multi-step manufacturing procedures.

Inventive Principle:

Principle #35Parameter changes

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 modified electrolyte suppresses side reactions with the positive electrode active material or a conductive material, thereby improving the chemical stability and electrochemical stability, thereby enhancing the chemical and electrochemical stability of the electrolyte.

Implementation Method 1

a coating film containing a functional group derived from a chalcogen-based compound is applied to the surface of the sulfide-based solid electrolyte, thereby suppressing side reactions at the interface thereof with a positive electrode active material or a conductive material

Methodology Applied

Scientific EffectAdsorption: Adsorption

Data Source

PatentUS20260005291A1Surface-modified composite solid electrolyte and preparing method thereof

Publication Date: 2026.01.01 SEOUL NATIONAL UNIVERSITY R&DB FOUNDATION

AI summary

Disclosed is a surface-modified composite solid electrolyte including a sulfide-based solid electrolyte particle; and a coating film formed on the surface of the sulfide-based solid electrolyte particle, the coating film containing a functional group derived from a chalcogenide-based compound represented by a chemical formula 1, and a method for preparing same.