Bilayer Ceramic Interconnect for Low-Permeability Tubular SOFCs

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Solution Overview

Problem

Current LaCrO3-based ceramic interconnects in tubular solid oxide fuel cells face challenges in manufacturability, durability, and cost due to Cr volatilization issues, leading to poor sinterability and high oxygen permeability, which result in fuel loss and increased manufacturing costs.

Innovation Solution

A bilayer ceramic interconnect composed of La0.8Sr0.2MnO3-δ (LSM) top-layer and Y- and Nb-doped SrTiO3-δ (SYTN) under-layer is co-sintered with a Ni-YSZ anode substrate, providing high electrical conductivity and low area specific resistance, while avoiding chemical reactions and oxygen permeability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If LCC thin-film is used as IC layer, then electrical conductivity and thermal expansion match are improved, but sinterability deteriorates due to Cr-vaporization inhibiting grain growth

Engineering Contradiction:

Improveelectrical conductivityVSAvoidsinterability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent removes Cr from the IC layer composition entirely, extracting the harmful element that causes vaporization and sintering problems. The new SYTN material (Sr1-xYxTi1-yNbyO3-δ) is Cr-free, eliminating the Cr+6 vaporization mechanism that prevents grain growth and densification during sintering, while maintaining electrical conductivity through Y and Nb doping.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses composite doping with both Y (yttrium) and Nb (niobium) in the SrTiO3 matrix to create SYTN material. Y doping provides ionic conductivity and structural stability, while Nb doping enhances electrical conductivity through electron donation. This composite doping strategy achieves both good sinterability and high electrical conductivity without Cr.

Inventive Principle:

Principle #40Composite materials

2Reliability

If LCC IC is used, then electrical conductivity is improved, but oxygen permeability increases due to Ca-acceptor doping creating oxygen vacancies

Engineering Contradiction:

Improveelectrical conductivityVSAvoidoxygen permeability

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent removes Ca (calcium) from the IC layer composition, extracting the acceptor dopant that creates oxygen vacancies. The new SYTN material uses donor dopants (Y and Nb) instead, which fill oxygen vacancies rather than creating them, thereby eliminating the oxygen permeability problem while maintaining electrical conductivity.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the doping mechanism from acceptor doping (Ca2+ substituting La3+) to donor doping (Y3+ substituting Sr2+ and Nb5+ substituting Ti4+). This parameter change in doping chemistry reverses the effect on oxygen vacancies: acceptor doping creates vacancies that increase oxygen permeability, while donor doping fills vacancies that reduce oxygen permeability while enhancing electrical conductivity.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If atmospheric plasma spray is used to deposit IC films, then sinterability is improved, but manufacturing cost increases

Engineering Contradiction:

ImprovesinterabilityVSAvoidmanufacturing cost

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent uses a conventional, cost-effective sintering process instead of expensive atmospheric plasma spray equipment. The SYTN material's inherent sinterability allows it to achieve dense microstructure through standard ceramic sintering, eliminating the need for costly plasma spray deposition equipment and reducing manufacturing complexity.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 bilayer ceramic interconnect achieves high electrical conductivity, ease of manufacturing, and cost-effectiveness, making it a strong candidate for next-generation durable tubular SOFCs.

Implementation Method 1

Y- and Nb-doping transforms semiconducting SrTiO3 into iterant large-polarons metal, confirming the high electrical conductivity

Methodology Applied

Scientific EffectLarge-polarons metal transformation:

Implementation Method 2

negligible oxygen permeability

Methodology Applied

Scientific EffectOxygen permeability blocking: Permeation

Implementation Method 3

serving as a physical barrier to prevent fuel and air from direct mixing

Methodology Applied

Scientific EffectPhysical barrier effect: Physical Containment

Data Source

PatentUS12531260B2Bilayer ceramic interconnect

Publication Date: 2026.01.20 UNIVERSITY OF SOUTH CAROLINA

AI summary

Described herein are new solid oxide fuel cell interconnects and methods for making same that may comprise a novel bilayer construct on an anode substrate to provide a dense microstructure, low area specific resistance, and negligible oxygen permeability to form a bilayer ceramic interconnect that is a strong candidate for next-generation, durable, and low-cost tubular solid oxide fuel cells.