Compliant Cathode Contact Materials for Solid Oxide Fuel Cells

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Solution Overview

Problem

Prior art fuel cell conductor/distributor materials exhibit suboptimal current conduction and gas flow distribution properties, are costly, and non-compliant at high temperatures, leading to fabrication and assembly challenges due to stringent tolerances.

Innovation Solution

A compliant cathode contact material, such as electrically conductive glass, metallic felt, or ceramic felt, is used between gas separators and cathode electrodes in solid oxide fuel cell stacks, which is elastic and chemically stable at high temperatures, allowing for stress absorption and reduced component constraints.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If prior art conductor/distributors (metal wire coils, wire grids, metal ribs) are used, then structural support is provided, but current conduction and gas flow distribution properties are suboptimal and manufacturing costs are high

Engineering Contradiction:

Improvecurrent conduction and gas flow distribution propertiesVSAvoidmanufacturing costs

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent employs porous metallic felt, foam, or mesh materials as conductor/distributors. These porous structures provide superior current conduction pathways and gas flow distribution compared to solid metal ribs or wire coils, while being more cost-effective to manufacture. The porous architecture allows simultaneous electrical conductivity and gas permeability without requiring complex assembled structures.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The invention uses composite materials combining metallic phases with binder materials to create conductor/distributor structures with optimized properties. The composite formulation enables tailored electrical conductivity, mechanical strength, and gas flow characteristics, improving performance while reducing manufacturing complexity and cost compared to traditional metal-only solutions.

Inventive Principle:

Principle #40Composite materials

2Reliability

If prior art conductor/distributors are used, then structural support is provided, but the materials are not compliant at high temperatures leading to tighter fuel cell tolerances

Engineering Contradiction:

Improvecompliance at high temperaturesVSAvoidfuel cell tolerances

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent utilizes materials whose mechanical properties change with temperature in a beneficial way. The metallic felt, foam, or mesh maintains compliance and elastic deformation capability at high fuel cell operating temperatures (700-1000°C), allowing the structure to accommodate thermal expansion and contraction without requiring tight manufacturing tolerances. This parameter change with temperature ensures continuous compliance throughout the operating range.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If non-compliant components are used, then assembly is simplified, but fabrication and assembly costs increase due to tighter fuel cell tolerances

Engineering Contradiction:

Improvefabrication and assembly costsVSAvoidfuel cell tolerances

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The compliant conductor/distributor material provides dynamic adaptation to dimensional changes in the fuel cell stack during operation. The material can elastically deform to accommodate thermal expansion, contraction, and differential movement between components, maintaining electrical contact and gas flow pathways without requiring precision-machined rigid structures. This dynamic compliance simplifies assembly while reducing manufacturing costs.

Inventive Principle:

Principle #15Dynamics

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 compliant cathode contact material improves current conduction and gas flow distribution, reduces manufacturing costs, and enhances the flexibility of stack components, minimizing tolerance-related failures and assembly complexities.

Implementation Method 1

an electrically conductive glass or an electrically conductive ceramic felt located between at least one of the plurality of gas separators and a cathode electrode

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

The compliant material may comprise an electrically conductive glass composite, a metallic felt, or a ceramic felt composite. The compliant material is preferably elastic and chemically stable at solid oxide fuel cell operating temperatures

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS7951509B2Compliant cathode contact materials

Publication Date: 2011.05.31 BLOOM ENERGY CORP

AI summary

A solid oxide fuel cell stack includes a plurality of solid oxide fuel cells, wherein each solid oxide fuel cell comprises an electrolyte located between an anode electrode and a cathode electrode, a plurality of gas separators, and at least one compliant cathode contact material. The contact material may be a metallic felt, foam or mesh, an electrically conductive glass or an electrically conductive ceramic felt located between at least one of the plurality of gas separators and a cathode electrode of an adjacent solid oxide fuel cell.