Cryolite-Structure Barium Tungsten Oxide for Universal Ionic Conduction

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Solution Overview

Problem

Current ionic conductors used in electrochemical devices have limitations in ionic conductivity and temperature-dependent properties, necessitating the development of new materials with novel crystal structures for diverse applications.

Innovation Solution

Development of metal composite oxides with a specific crystal structure characterized by a space group of Fd-3m and unit cell parameter of 17.0±1.0 Å, featuring ordered metal sites and defects that form an ion channel for enhanced ionic conductivity, allowing for both oxygen and hydrogen ion conduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional ionic conductors (YSZ, doped ceria, perovskite phases) are used, then ionic conductivity is achieved at specific temperatures, but the materials exhibit limited versatility and require different materials for different temperature ranges and applications

Engineering Contradiction:

Improveapplicability across different temperatures and devicesVSAvoidionic conductivity performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent develops a universal ionic conductor material (barium tungsten oxide with cryolite structure) that can function across a wide temperature range (room temperature to high temperature) and in multiple electrochemical devices (fuel cells, oxygen pumps, gas sensors, electrolyzers). This single material system replaces the need for multiple specialized materials, achieving both versatility and maintained performance through its unique cubic crystal structure with ordered metal sites and defects.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Temperature

If YSZ is used for high-temperature SOFC, then high-temperature ionic conductivity is achieved, but electrical conductivity is very low making it unsuitable for oxygen pumps

Engineering Contradiction:

Improveoperating temperature rangeVSAvoidelectrical conductivity

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent changes the fundamental crystal structure parameter from fluorite (YSZ) or perovskite to cryolite structure, which inherently provides both high ionic conductivity and acceptable electrical conductivity across a wide temperature range. This structural parameter change enables the material to function as both solid oxide fuel cell electrolyte and oxygen pump membrane without sacrificing either ionic or electrical conductivity.

Inventive Principle:

Principle #35Parameter changes

3Temperature

If doped ceria is used for low-temperature SOFC, then low-temperature ionic conductivity is improved, but the material requires protective layers for cathode protection

Engineering Contradiction:

Improveoperating temperatureVSAvoidstructure complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The barium tungsten oxide material with cryolite structure serves as a universal electrolyte that performs both low-temperature fuel cell operation and provides inherent cathode protection without requiring additional protective layers. This eliminates the multi-layer complexity associated with doped ceria systems while maintaining low-temperature functionality.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Productivity

If new crystal structures are developed, then thousands of derivatives can be synthesized for rapid technology development, but the crystal structure determination and characterization becomes increasingly difficult

Engineering Contradiction:

Improverate of material developmentVSAvoidcrystal structure characterization

Core Design Contradiction:

ProductivityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent focuses on locally optimizing specific crystallographic features within the cryolite structure - specifically the ordering of metal sites (Ba at 8a, W at 16c) and the creation of ordered defects at specific positions. This localized structural optimization provides clear, identifiable characteristics that facilitate characterization while enabling systematic derivation of new materials with controlled properties.

Inventive Principle:

Principle #3Local quality

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 novel crystal structure enables high ionic conductivity across various temperatures, facilitating the development of advanced electrochemical devices such as fuel cells, oxygen pumps, and gas sensors with improved performance.

Implementation Method 1

a barium-tungsten oxide with an ion channel formed for easy movement of ions due to crystallographic specificity resulting from the ordering of metal ion sites and metal ion defects within a unit cell

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Data Source

PatentUS7476376B2Metal composite oxide with novel crystal structure and their use as ionic conductors

Publication Date: 2009.01.13 LG CHEM LTD

AI summary

Disclosed is metal composite oxides having the new crystal structure. Also disclosed are ionic conductors including the metal composite oxides and electrochemical devices comprising the ionic conductors. The metal composite oxides have an ion channel formed for easy movement of ions due to crystallographic specificity resulting from the ordering of metal ion sites and metal ion defects within the unit cell. Therefore, the metal composite oxides according to the present invention are useful in an electrochemical device requiring an ionic conductor or ionic conductivity.