Coated 5V Cathode Material for Stable Sulfide Solid-State Batteries

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing lithium-ion batteries face issues of low thermal stability, ignitability, and leakage due to the use of organic liquid electrolytes, and sulfide-based solid electrolytes are electrochemically unstable when in direct contact with 5V-class positive electrode active materials, leading to side reactions and reduced performance.

Innovation Solution

A composite positive electrode active material is developed, comprising a 5V-class positive electrode active material coated with a compound represented by Chemical Formula 2, which combines lithium halides and lithium titanium halides, enhancing electrochemical stability and ionic conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If sulfide-based solid electrolyte is used, then ionic conductivity is improved, but electrochemical stability deteriorates due to side reactions with 5V-class positive electrode active materials

Engineering Contradiction:

Improveionic conductivityVSAvoidelectrochemical stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

An oxide-based solid electrolyte shell is introduced as an intermediary layer between the sulfide-based solid electrolyte and the 5V-class positive electrode active material. This shell prevents direct contact and side reactions while maintaining ionic conductivity, as the oxide shell serves as a protective barrier that allows ion transport without chemical degradation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The positive electrode active material is constructed as a composite structure with an oxide-based solid electrolyte shell coating the core 5V-class active material. This composite structure combines the high ionic conductivity of sulfide-based electrolytes with the electrochemical stability of oxide-based materials, achieving both properties simultaneously.

Inventive Principle:

Principle #40Composite materials

2Reliability

If oxide-based solid electrolyte shell is added to prevent side reactions, then electrochemical stability is improved, but ionic conductivity deteriorates due to resistive layer formation

Engineering Contradiction:

Improveelectrochemical stabilityVSAvoidionic conductivity

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The thickness and composition parameters of the oxide-based solid electrolyte shell are optimized to balance protection and conductivity. By controlling the shell thickness to be sufficiently thin and selecting appropriate oxide compositions, the resistive effect is minimized while maintaining electrochemical stability, allowing ions to pass through efficiently.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If organic liquid electrolyte is used, then ease of manufacture is improved, but safety deteriorates due to low thermal stability, ignitability, and leakage

Engineering Contradiction:

Improveease of manufactureVSAvoidthermal stability

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The electrolyte is transitioned from liquid phase (organic liquid electrolyte) to solid phase (sulfide-based and oxide-based solid electrolytes). This phase transition eliminates the leakage and ignitability issues associated with liquid electrolytes while maintaining manufacturability through established solid-state battery fabrication techniques.

Inventive Principle:

Principle #36Phase transitions

Data Source

PatentUS20260038841A1Composite positive electrode active material, positive electrode containing the same, and all-solid-state battery containing the same

Publication Date: 2026.02.05 UI (UNIVERSITY IND FOUNDATION) YONSEI UNIVERSITY

AI summary

An embodiment provides a composite positive electrode active material including: a positive electrode active material represented by Chemical Formula 1; and a coating layer on a surface of the positive electrode active material, the coating layer including a compound represented by Chemical Formula 2.Chemical Formula 1 and Chemical Formula 2 are as described in the specification.