Sodium Polysulfide Melt Synthesis for Open-Air Sulfide Production

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Solution Overview

Problem

The existing methods for producing alkali metal-containing sulfides, such as lithium-containing sulfides, require vacuum-sealing in a quartz ampule to prevent sulfur volatilization during firing, which is time-consuming and not suitable for mass production.

Innovation Solution

A method for producing metal and/or metalloid-containing sulfides under normal pressure using a melt obtained by heating a first sodium polysulfide represented by Na2Sx (1<x≤5) as a reaction medium and sulfur source, eliminating the need for vacuum-sealing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If vacuum-sealing in a quartz ampule is performed to prevent sulfur volatilization, then sulfur loss is reduced, but production time and operational complexity increase

Engineering Contradiction:

Improvesulfur lossVSAvoidproduction time

Core Design Contradiction:

Loss of substanceVSLoss of time

Solution Approach 1:

Sodium polysulfide is introduced as an intermediary substance that serves dual functions: as a reaction medium for the synthesis reaction and as a sulfur source to compensate for sulfur volatilization. This eliminates the need for vacuum-sealing while preventing sulfur loss, resolving the contradiction between substance retention and production efficiency

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the physical state parameter of the reaction system from solid-state (requiring sealing) to melt-state (open system acceptable). By conducting the reaction in a molten sodium polysulfide medium, sulfur volatilization is suppressed through the liquid phase environment, allowing open-system processing and eliminating time-consuming sealing operations

Inventive Principle:

Principle #35Parameter changes

2Loss of substance

If vacuum-sealing in a quartz ampule is performed to prevent sulfur volatilization, then sulfur loss is reduced, but device complexity increases

Engineering Contradiction:

Improvesulfur lossVSAvoidsealing treatment

Core Design Contradiction:

Loss of substanceVSDevice complexity

Solution Approach 1:

Sodium polysulfide acts as an intermediary that simplifies the overall process by eliminating the need for complex vacuum-sealing apparatus. The melt medium inherently suppresses sulfur loss without requiring additional sealing components or procedures, reducing device complexity while maintaining sulfur retention

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The sodium polysulfide medium performs self-service by automatically compensating for sulfur volatilization through its own composition. The excess sulfur in the polysulfide structure naturally replenishes any sulfur loss during heating, making external sealing measures unnecessary and simplifying the equipment requirements

Inventive Principle:

Principle #25Self-service

3Reliability

If conventional firing treatment is performed in inert atmosphere, then sulfur volatilization is prevented through sealing, but productivity decreases

Engineering Contradiction:

Improvesulfur volatilization controlVSAvoidmass production capability

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The invention changes the reaction medium from solid to liquid (melt) state, which fundamentally alters the volatilization behavior of sulfur. In the molten sodium polysulfide medium, sulfur remains dissolved or suspended in the liquid phase, preventing volatilization without requiring sealed containers, thereby enabling high-productivity mass production

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Sodium polysulfide serves as a reactive intermediary medium that facilitates both the synthesis reaction and sulfur retention simultaneously. This dual functionality eliminates the need for separate sealing operations, allowing continuous processing and significantly improving productivity for mass production applications

Inventive Principle:

Principle #24Intermediary (Mediator)

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 allows for the efficient production of novel metal and/or metalloid-containing sulfides without the need for vacuum-sealing, thereby facilitating mass production and achieving high uniformity in the sulfide products.

Implementation Method 1

using a melt obtainable by heating a first sodium polysulfide represented by Na2Sx (1<x≤5)

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentUS20250026640A1Method for producing metal and/or metalloid-containing sulfide, and sodium-containing sulfide

Publication Date: 2025.01.23 PUBLIC UNIVERSITY CORPORATION OSAKA CITY UNIVERSITY

AI summary

The present addresses the problem of providing a new method for producing a metal and/or metalloid-containing sulfide. The problem is solved by a method for producing a metal and/or metalloid-containing sulfide characterized by using as a reaction medium and sulfur source a melt that can be obtained by heating a first sodium polysulfide represented by Na2Sx (in the formula, 1<x≤5) and synthesizing a sulfide containing a metal and/or metalloid (where the metal is neither an alkali metal nor an alkaline earth metal) under normal pressure.