α-Li3PS4 Solid Electrolyte Heating for Room-Temperature Phase Retention

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Solution Overview

Problem

It is difficult to maintain the α-Li3PS4 phase, known for its high electric conductivity, at room temperature in L-P-S sulfide-based solid electrolytes.

Innovation Solution

A method involving controlled heating of Li ion conductive sulfide materials containing Li, P, and S, with or without F and/or Cl, at specific temperature ranges and rates to stabilize the α-Li3PS4 phase at room temperature.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional heating methods are used to obtain α-Li3PS4 phase, then high electric conductivity is achieved, but the phase cannot be retained at room temperature

Engineering Contradiction:
Improveelectric conductivityVSAvoidphase stability at room temperature
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies parameter changes by controlling the heating rate (≥100°C/min at 200°C) and temperature range (230-350°C) to transform the stable phase at room temperature from the conventional low-conductivity phase to the high-conductivity α-Li3PS4 phase. This rapid heating process modifies the thermal parameters to achieve phase retention at room temperature that would otherwise be unstable.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs preliminary action by performing rapid heating treatment before cooling to room temperature. The α-Li3PS4 phase is formed during the rapid heating process, and this phase structure is then preserved during subsequent cooling, allowing the high-conductivity phase to be retained at room temperature rather than transforming to a different phase.

Inventive Principle:
Principle #10Preliminary action

2Stability of the object's composition

If rapid heating is applied to form α-Li3PS4 phase, then room temperature phase retention is achieved, but manufacturing process complexity increases

Engineering Contradiction:
Improvephase stability at room temperatureVSAvoidheating process control complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent simplifies the manufacturing process by defining specific parameter ranges: heating rate of ≥100°C/min at 200°C and temperature range of 230-350°C. These quantified parameters provide clear manufacturing guidelines that reduce process complexity while ensuring consistent formation of the α-Li3PS4 phase with room temperature stability.

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

The method enables the production of solid electrolyte materials with the α-Li3PS4 phase that retain excellent conductivity at room temperature, enhancing battery performance.

Implementation Method 1

heating a Li ion conductive sulfide material containing Li, P and S but free of F and Cl and having no α-Li3PS4 phase to a temperature within a range from 230°C to 350°C, wherein a temperature increase rate at 200°C is 100°C/min or more

Methodology Applied
Scientific EffectPhase transition: Phase Change

Implementation Method 2

heating a Li ion conductive sulfide material containing Li, P, P and S as well as F and/or Cl and having no α-Li3PS4 phase to a temperature within a range from 200°C to 300°C

Methodology Applied
Scientific EffectCrystallization: Crystallisation

Data Source

PatentEP4614532A1Method for producing solid electrolyte material having ?-li3PS4 phase, and solid electrolyte material
Publication Date: 2025.09.10 PUBLIC UNIVERSITY CORPORATION OSAKA CITY UNIVERSITY
  • EP4614532A1 patent drawingFigure 1~2
  • EP4614532A1 patent drawingFigure 3
  • EP4614532A1 patent drawingFigure 4

AI summary

A subject is to provide a method for manufacturing a solid electrolyte material having an α-Li3PS4 phase. The subject is addressed by a method for manufacturing a solid electrolyte material having the α-Li3PS4 phase, comprising heating a Li ion conductive sulfide material to a temperature within a range from 230°C to 350°C, the Li ion conductive sulfide material containing Li, P and S but free of F and Cl and having no α-Li3PS4 phase, wherein a temperature increase rate at 200°C is 100°C/min or more.