Sulfide Solid Electrolyte Crystallinity Control for Conductivity

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Solution Overview

Problem

Sulfide solid electrolytes in lithium secondary batteries face challenges with chemical stability and low lithium ion conductivity, limiting their operational stability and efficiency compared to oxide solid electrolytes.

Innovation Solution

A method for preparing a sulfide solid electrolyte involves calcining a precursor to form a crystalline Li4+xPS4I1+x structure, which is then pulverized to create a particulate form with enhanced lithium ion conductivity by adjusting the degree of crystallinity, thereby reducing interfacial resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sulfide solid electrolyte is used to achieve high lithium ion conductivity, then lithium ion conductivity is improved, but chemical stability deteriorates

Engineering Contradiction:

Improvelithium ion conductivityVSAvoidchemical stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies parameter changes by precisely controlling the compositional parameters (x and y in Li4+xPS4I1-y) and processing parameters (calcination temperature, pulverization conditions) to achieve a specific crystalline phase with optimal balance between conductivity and stability. The controlled deviation from stoichiometric composition allows tuning of electrochemical stability while maintaining high ionic conductivity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite structure by forming a crystalline phase within a glass ceramic matrix. This composite approach combines the high ionic conductivity of crystalline regions with the chemical stability and structural flexibility of the glass ceramic phase, achieving synergistic properties that overcome the limitations of purely crystalline or purely glassy sulfide electrolytes.

Inventive Principle:

Principle #40Composite materials

2Reliability

If crystalline structure is formed to improve lithium ion conductivity, then conductivity is improved, but interfacial resistance increases

Engineering Contradiction:

Improvelithium ion conductivityVSAvoidinterfacial resistance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by creating regions with different structural characteristics within the electrolyte. The crystalline phases provide high ionic conductivity pathways, while the glass ceramic matrix ensures good interfacial contact and chemical stability. This spatial differentiation of properties allows simultaneous achievement of high bulk conductivity and low interfacial resistance.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent utilizes a glass ceramic matrix that can be considered a porous or heterogeneous structure at the micro scale, providing numerous interfaces and contact points that reduce interfacial resistance. The glassy phase fills gaps and creates intimate contact between crystalline regions and electrode surfaces, facilitating efficient ion transport across interfaces.

Inventive Principle:

Principle #31Porous materials

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 particulate sulfide solid electrolyte achieves lithium ion conductivity of 1.0 mS/cm or greater and reduces interfacial resistance, improving the stability and performance of lithium secondary batteries.

Implementation Method 1

treating the crystalline solid electrolyte to obtain a particulate solid electrolyte. The crystalline solid electrolyte suitably may be treated by mechanical force to obtain a particulate solid electrolyte, for example the crystalline solid electrolyte may be pulverized to obtain a particulate solid electrolyte

Methodology Applied

Scientific EffectMechanical force: Mechanical Force