La(Fe1-xAlx)O3 Interconnector Material for Solid Electrolyte Fuel Cells

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Solution Overview

Problem

Lanthum chromite-based interconnectors in solid electrolyte fuel cells face challenges such as high sintering temperatures, reactivity with other materials, and environmental concerns like chromium evaporation, leading to inefficient production and low electrical conductivity.

Innovation Solution

A ceramic composition represented by La(Fe1-xAlx)O3, where 0<x<0.5, is used as the interconnector material, offering chemical stability, low ionic conductivity, and high electron conductivity, allowing for sintering at reduced temperatures and eliminating chromium content.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lanthanum chromite is used as interconnector material, then chemical stability and electrical conductivity are improved, but sintering temperature becomes excessively high and chromium evaporation occurs

Engineering Contradiction:

Improvechemical stabilityVSAvoidsintering temperature

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent changes the chemical composition parameters of the interconnector material from lanthanum chromite (LaCrO3) to lanthanum ferrite (LaFeO3) and its doped variants. This composition change allows sintering at lower temperatures (1200-1400°C) while maintaining chemical stability and electrical conductivity, thereby resolving the contradiction between reliability and sintering temperature.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent eliminates the harmful chromium evaporation issue by completely replacing chromium-containing materials with chromium-free lanthanum ferrite-based materials. This substitution maintains the desired chemical stability and electrical conductivity while converting the harmful chromium evaporation problem into a beneficial environmentally friendly solution.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If lanthanum chromite is sintered at high temperature to achieve densification, then gas-tightness is improved, but chromium evaporation and loss of substance occur

Engineering Contradiction:

Improvegas-tightnessVSAvoidchromium evaporation

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent eliminates chromium evaporation by completely replacing chromium-containing lanthanum chromite with chromium-free lanthanum ferrite-based materials. This substitution maintains gas-tightness through proper sintering at lower temperatures while converting the harmful chromium loss into a beneficial chromium-free solution.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the sintering temperature parameter from high temperature (required for lanthanum chromite) to lower temperature (1200-1400°C for lanthanum ferrite). This parameter change achieves adequate densification and gas-tightness without causing chromium evaporation, resolving the contradiction between reliability and substance loss.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If lanthanum chromite is used as interconnector material, then electrical conductivity is improved, but production efficiency deteriorates due to high sintering temperature requirements

Engineering Contradiction:

Improveelectrical conductivityVSAvoidproduction efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes the sintering temperature parameter from high temperature (required for lanthanum chromite) to lower temperature (1200-1400°C for lanthanum ferrite). This parameter change maintains high electrical conductivity while significantly improving production efficiency by reducing energy consumption and enabling faster production cycles.

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 La(Fe1-xAlx)O3 interconnector material enables stable operation in high-temperature environments with reduced sintering temperatures, improved electrical conductivity, and environmental safety, enhancing the efficiency and cost-effectiveness of solid electrolyte fuel cells.

Implementation Method 1

the interconnector material... has a high electric conductivity and can reduce an ohmic loss (IR loss)

Methodology Applied

Scientific EffectElectron conduction: Conduction (electrical)

Implementation Method 2

the interconnector material... has a low ionic conductivity

Methodology Applied

Scientific EffectIonic conduction resistance: Conduction (electrical)

Data Source

PatentUS9941524B2Interconnector material, intercellular separation structure, and solid electrolyte fuel cell

Publication Date: 2018.04.10 MURATA MFG CO LTD

AI summary

Provided is an interconnector material which is chemically stable in both oxidation atmospheres and reduction atmospheres, has a high electron conductivity (electric conductivity), a low ionic conductivity, does not contain Cr, and enables a reduction in sintering temperature. The interconnector material is arranged between a plurality of cells each composed of an anode layer, a solid electrolyte layer, and a cathode layer stacked sequentially, and electrically connects the plurality of cells to each other in series in a solid electrolyte fuel cell. The interconnector is formed of a ceramic composition represented by the composition formula La(Fe1-xAlx)O3 in which 0<x<0.5.