Sulfide Solid Electrolyte Calcination with Nitrogen Gas Purging

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Solution Overview

Problem

The preparation of LiPSX (X=Cl, Br, or I) solid electrolytes faces challenges in achieving high-purity and high ionic conductivity due to issues with calcination processes, particularly the generation of hydrogen sulfide gas and reactant leakage, which affects reaction efficiency and stability.

Innovation Solution

A method involving mechanical milling of a raw material composition containing phosphorous sulfide, lithium halide, and lithium sulfide, followed by a calcination process with a purge gas to remove hazardous gases and maintain reaction efficiency, including heating to 500°C or higher, maintaining for 4-10 hours, and cooling to room temperature, with the purge process performed during these steps to prevent reactant loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If dry milling based on mechanical milling methods is used for synthesis, then ionic conductivity is relatively good, but hydrogen sulfide gas is generated during calcination processes causing stability problems and reactant leakage

Engineering Contradiction:

ImprovestabilityVSAvoidhydrogen sulfide gas generation

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies inert atmosphere by conducting the calcination process in a nitrogen-purged environment. The nitrogen gas prevents oxidation of sulfur compounds during heating, thereby eliminating hydrogen sulfide gas generation while maintaining the dry milling synthesis method's ionic conductivity benefits. The reactive atmosphere is replaced with an inert one to prevent harmful chemical reactions.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

2Productivity

If purge process is performed during calcination, then reactant loss is reduced and reaction efficiency is improved, but process complexity increases

Engineering Contradiction:

Improvereaction efficiencyVSAvoidprocess complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent implements continuous nitrogen purging throughout the entire calcination process rather than intermittent purging. The nitrogen flow is maintained continuously during heating, holding, and cooling stages to consistently prevent reactant leakage and hydrogen sulfide generation. This continuous action ensures high reaction efficiency without requiring complex intermittent control mechanisms.

Inventive Principle:

Principle #20Continuity of useful action

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 enhances the purity and ionic conductivity of the solid electrolyte, improving reaction efficiency and stability, thereby supporting the development of high-performance all-solid-state secondary batteries.

Implementation Method 1

a purge process using a gas is performed in the S3 calcining

Methodology Applied

Scientific EffectGas purging:

Implementation Method 2

S3 of calcining the compound obtained through the mechanical milling

Methodology Applied

Scientific EffectThermal heating: Heating

Data Source

PatentUS20230416091A1Method for preparing solid electrolyte for secondary battery

Publication Date: 2023.12.28 INCHEMS CO LTD

AI summary

The present specification provides a method for preparing a solid electrolyte for a secondary battery, comprising the steps of: (S1) preparing a material composition comprising phosphorus (P) sulfide, a lithium halide and lithium sulfide; (S2) mechanically milling the material composition in a milling container; and (S3) calcining a compound obtained after the milling step, wherein the calcination step (S3) performs purging using gas.