Argyrodite Solid Electrolyte With Low Lattice Strain for Li-Ion Conductivity

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Solution Overview

Problem

Existing solid electrolytes do not effectively control the argyrodite rate or lattice strain, which limits their lithium ion conductivity.

Innovation Solution

A solid electrolyte with a high argyrodite rate (97 wt% or more) and controlled lattice strain (less than 0.10%) is achieved by using a compound with an argyrodite-type crystal structure, represented by LiaPSbXc, where X is an elemental halogen, and optimizing the calcination process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional solid electrolyte compositions are used, then the basic structure is established, but the lithium ion conductivity remains insufficient due to uncontrolled argyrodite rate and lattice strain

Engineering Contradiction:
Improvelithium ion conductivityVSAvoidargyrodite rate control
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by precisely controlling the compositional parameters (a, b, c) in the formula LiaPSbXc and the calcination temperature (300-500°C) to achieve the desired argyrodite rate of 97 wt% or more and lattice strain of less than 0.10%, thereby resolving the contradiction between achieving high lithium ion conductivity and controlling manufacturing precision

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs feedback control by using XRD analysis to measure the argyrodite rate and adjusting the calcination conditions accordingly to ensure the argyrodite rate reaches 97 wt% or more, which directly improves lithium ion conductivity while maintaining precise control over the crystal structure

Inventive Principle:
Principle #23Feedback

2Reliability

If the argyrodite rate is increased to improve lithium ion conductivity, then the conductivity increases, but the manufacturing complexity increases due to lack of specific control methods

Engineering Contradiction:
Improvelithium ion conductivityVSAvoidprocess control complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent simplifies the process control by establishing specific parameter ranges: calcination temperature of 300-500°C, composition parameters a (3.0-6.0), b (3.5-4.8), and c (0.1-3.0), which automatically guide the manufacturing process to achieve high argyrodite rate without requiring complex control systems

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies preliminary action by pre-determining the optimal calcination temperature range (300-500°C) and composition parameters before manufacturing, allowing the process to naturally achieve the desired argyrodite rate of 97 wt% or more without requiring complex real-time adjustments during production

Inventive Principle:
Principle #10Preliminary 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

The solid electrolyte exhibits significantly improved lithium ion conductivity, reaching values of 4.0 mS/cm or more at room temperature, due to the high argyrodite rate and controlled lattice strain.

Implementation Method 1

High lithium ion conductivity is one of the characteristics required of solid electrolytes

Methodology Applied
Scientific EffectLithium ion conduction: Conduction (electrical)

Implementation Method 2

a compound that has a crystal phase having an argyrodite-type crystal structure

Methodology Applied
Scientific EffectCrystallisation: Crystallisation

Data Source

PatentUS12334497B2Solid electrolyte, and electrode mixture, solid electrolyte layer and solid-state battery, each using same
Publication Date: 2025.06.17 MITSUI MINING & SMELTING CO LTD

AI summary

A solid electrolyte contains a compound that has a crystal phase having an argyrodite-type crystal structure and that is represented by LiaPSbXc, where X is at least one elemental halogen, a represents a number of 3.0 or more and 6.0 or less, b represents a number of 3.5 or more and 4.8 or less, and c represents a number of 0.1 or more and 3.0 or less. The proportion of the crystal phase with an argyrodite-type structure relative to all crystal phases constituting the solid electrolyte is 97.0 wt % or more. The compound has a lattice strain of less than 0.10%. The solid electrolyte preferably exhibits a lithium ion conductivity of 4.0 mS/cm or more.