Lithium Sulfide Spray Drying for Oxygen Content Control

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Solution Overview

Problem

Existing methods for synthesizing lithium sulfide face challenges such as poor kinetic control, reliance on expensive raw materials, high processing costs, and environmental concerns, particularly in managing the drying process to achieve high-purity lithium sulfide.

Innovation Solution

A method involving mixing a carbon-based material with a lithium compound, filtering, spray-drying under an inert loop structure at 110°C to 160°C, and heat-treating the powder to produce lithium sulfide with controlled particle size and impurity content, utilizing a recirculation process to reduce impurities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional drying methods are used for the extraction solution, then the processing is simpler, but the oxygen content in the resulting lithium sulfide increases above 2.8%

Engineering Contradiction:
Improveoxygen content controlVSAvoiddrying process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by precisely controlling the drying temperature within 110°C to 160°C range and maintaining specific atmospheric conditions during drying. This controlled parameter approach ensures oxygen content remains below 2.8% while managing process complexity through defined operational parameters.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs an inert atmosphere during the drying process to prevent oxidation and control oxygen content in the final lithium sulfide product. By maintaining an inert environment throughout the drying stage, the method achieves high purity without requiring excessively complex equipment modifications.

Inventive Principle:
Principle #39Inert atmosphere (Inert environment)

2Object-affected harmful factors

If the carbonthermal reduction method is used, then environmental friendliness improves by avoiding toxic H2S gas, but challenges arise in managing extraction solution properties and achieving high product purity

Engineering Contradiction:
Improvetoxic gas eliminationVSAvoidproduct purity
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent applies extraction by using a solvent to separate lithium sulfide from the carbonthermal reduction mixture. The extraction solution is then carefully dried under controlled conditions to isolate high-purity lithium sulfide, achieving both environmental benefits and product purity requirements.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent controls physical parameters including drying temperature (110°C to 160°C), atmospheric composition, and drying duration to optimize both the environmental advantages of carbonthermal reduction and the purity of the final lithium sulfide product.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If high-energy ball milling or wet plasma processing is used, then lithium sulfide can be synthesized, but processing costs increase and kinetic control becomes poor

Engineering Contradiction:
Improvesynthesis feasibilityVSAvoidprocessing efficiency
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The patent replaces high-energy mechanical ball milling with a chemical reduction approach followed by controlled drying. This substitution eliminates the need for expensive high-energy equipment while maintaining synthesis feasibility and improving kinetic control through chemical reaction mechanisms.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent optimizes processing efficiency by controlling drying parameters (temperature, atmosphere, time) to achieve rapid and complete solvent removal. This parameter optimization enables high productivity without requiring expensive plasma processing equipment.

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

This method enables the production of high-purity lithium sulfide with reduced impurities, specifically oxygen content below 2.8%, ensuring consistent quality and stability for use in solid-state electrolytes.

Implementation Method 1

spray-drying the filtrate at a temperature in the range of 110°C to 160°C

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 2

heat-treating the resulting spray-dried powder, thereby producing lithium sulfide having an oxygen content of less than 2.8%

Methodology Applied
Scientific EffectHeat treatment: Heat Treatment

Data Source

PatentEP4635911A1Method for preparing lithium sulfide
Publication Date: 2025.10.22 POSCO HLDG INC
  • EP4635911A1 patent drawingFigure 1a~1b
  • EP4635911A1 patent drawingFigure 2a~2b
  • EP4635911A1 patent drawingFigure 2c~2d

AI summary

The present invention relates to a method for producing lithium sulfide, the method comprising: mixing a carbon material and a lithium compound to prepare a lithium-carbon compound; filtering a solution obtained by mixing the lithium-carbon compound with a solvent; spray-drying the filtrate in an inert loop structure at a temperature ranging from 110°C to 160°C; and heat-treating the spray-dried product, whereby lithium sulfide having an oxygen content of less than 2.8% can be produced.