Organic-Coated Sulfide Electrolytes for Dense Solid-State Pellets

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Solution Overview

Problem

Existing solid state batteries face challenges with sulfide-based solid electrolytes due to potential losses in Li ion transfer paths, lithium dendrite penetration, and mechanical brittleness, which affect safety, performance, and lifespan.

Innovation Solution

A sulfide-containing solid state electrolyte material is modified with an organic coating, such as a long chain thiol, to enhance densification, ionic conductivity, and mechanical properties, thereby improving the safety and performance of solid state batteries.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If sulfide-based solid electrolyte is used to achieve high ionic conductivity, then ionic conductivity is improved, but mechanical brittleness and susceptibility to cracks increase

Engineering Contradiction:

Improveionic conductivityVSAvoidmechanical strength

Core Design Contradiction:

Use of energy by moving objectVSStrength

Solution Approach 1:

The patent applies composite materials by combining sulfide-based solid electrolyte particles with a polymer matrix to create a composite solid electrolyte. The polymer matrix provides mechanical strength and flexibility while the sulfide particles maintain high ionic conductivity, thus resolving the contradiction between ionic conductivity and mechanical strength.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the physical and chemical parameters of the sulfide electrolyte by coating particles with polymer materials and controlling particle size distribution. This modifies the mechanical properties and fracture behavior, reducing brittleness while preserving ionic conductivity pathways.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If sulfide solid electrolyte is densified to reduce voids and improve safety, then safety is improved, but Li ion transfer path loss due to cracks increases

Engineering Contradiction:

ImprovesafetyVSAvoidion transfer path integrity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent uses a polymer coating as a flexible shell around sulfide electrolyte particles. This flexible polymer layer accommodates volume changes and prevents crack formation during densification and battery operation, maintaining ion transfer paths while improving safety by eliminating voids.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The polymer matrix provides beforehand cushioning by absorbing mechanical stress and preventing crack propagation before they can compromise ion transfer paths. This protective effect is built into the composite structure prior to battery operation.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Volume of stationary object

If organic coating is applied to sulfide electrolyte to enhance densification, then density is improved, but interface complexity increases

Engineering Contradiction:

ImprovedensityVSAvoidinterface complexity

Core Design Contradiction:

Volume of stationary objectVSDevice complexity

Solution Approach 1:

The patent applies local quality by coating only the surface of sulfide electrolyte particles with polymer material rather than modifying the bulk properties. This localized approach enhances densification and interfacial compatibility without significantly complicating the overall interface structure or processing.

Inventive Principle:

Principle #3Local quality

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 organic coating significantly increases the density and stability of the sulfide solid state electrolyte, reducing lithium dendrite penetration and enhancing the critical current density by four times, allowing for prolonged cycling without failure.

Implementation Method 1

modifying the interface structure facilitates the ionic and lithium atomic diffusion coefficient at sulfide grain boundaries during pressing, thus achieving the densification of sulfide solid state electrolyte

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 2

A sulfide-containing solid state electrolyte material is modified with an organic coating, such as a long chain thiol

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 3

The organic coating significantly increases the density and stability of the sulfide solid state electrolyte, reducing lithium dendrite penetration

Methodology Applied

Scientific EffectPhysical barrier:

Data Source

PatentUS20250125410A1Method for densification of sulfide solid electrolytes

Publication Date: 2025.04.17 LG ENERGY SOLUTION LTD

AI summary

Disclosed is a sulfide-containing solid electrolyte material with an organic coating, as well as densified pellets containing this solid electrolyte material, a solid electrolyte thereof, and a solid state battery containing the solid electrolyte. According to aspects of the disclosure, the coating comprising a compound of Chemical Formula (1) or Chemical Formula (2) is formed on the surface of a sulfide-containing solid electrolyte material, e.g., the organic coating may comprise a compound having a thiol with a long hydrophobic tail, such as 1-undecanethiol. The coating provides densification of sulfide-containing solid electrolyte materials, and facilitates the ionic and lithium atomic diffusion coefficient at sulfide grain boundaries during pressing, thus achieving the densification of sulfide solid state electrolyte.