Solid Oxide Fuel Cell Electrolyte Sheet Surface Roughness Design

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Solution Overview

Problem

The existing electrolyte sheets for solid oxide fuel cells (SOFCs) face challenges in maintaining handling strength, preventing gas leaks, and ensuring stable power generation due to inadequate surface roughness, which affects adhesion and delamination resistance, especially during temperature fluctuations.

Innovation Solution

The electrolyte sheet features distinct surface roughness values between the peripheral and non-peripheral regions, with specific ranges (0.05-0.3 μm and 0.2-1.2 μm respectively) to enhance handling strength and adhesiveness, and a production method involving a roughening mold plate to achieve these surface characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the surface roughness of the electrolyte sheet is increased to improve adhesion and electrode contact area, then the power generation performance is enhanced, but the handling strength decreases and the sheet becomes prone to cracking

Engineering Contradiction:
Improvepower generation performanceVSAvoidhandling strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The electrolyte sheet is designed with different surface roughness values in different regions: the peripheral region has a surface roughness of 0.05-0.3 μm for handling strength, while the non-peripheral region has a surface roughness of 0.2-1.2 μm for electrode adhesion. This local differentiation allows each region to optimize its function without compromising the other.

Inventive Principle:
Principle #3Local quality

2Reliability

If the surface roughness is increased to improve the reaction area of the electrode, then the three-phase boundary area is enhanced, but the thermal shock resistance against heat cycles deteriorates

Engineering Contradiction:
Improvereaction areaVSAvoidthermal shock resistance
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The non-peripheral region has a surface roughness of 0.2-1.2 μm to provide sufficient reaction area for electrochemical reactions, while the peripheral region has a surface roughness of 0.05-0.3 μm to maintain thermal shock resistance and prevent cracking during heat cycles. This local differentiation allows both requirements to be satisfied simultaneously.

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

This configuration improves handling strength, reduces gas leaks, and maintains stable power generation performance by optimizing surface roughness for gas sealing and electrode adhesion, leading to enhanced reliability and reduced production costs for SOFCs.

Implementation Method 1

zirconia-based ceramic sheets have a superior oxygen ion conductivity... utilized as solid electrolytes for sensors, such as oxygen sensor and humidity sensor, and further as a solid electrolyte for SOFC

Methodology Applied
Scientific EffectOxygen ion conductivity: Fast Ion Conductor

Implementation Method 2

the adherence of the electrolyte sheet to the electrode layers formed on both sides of the sheet... are improved

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP2555296B1Electrolyte sheet for solid oxide type fuel cell and process for production thereof, single cell for solid oxide type fuel cell, and solid oxide type fuel cell
Publication Date: 2016.11.23 NIPPON SHOKUBAI CO LTD
  • EP2555296B1 patent drawingFigure 1

AI summary

The electrolyte sheet for solid oxide fuel cell of the present invention has different surface roughnesses between the peripheral region and the region other than the peripheral region at least on one side. The surface roughness Ra(b) in the peripheral region is at least 0.05 µm and less than 0.3 µm. The surface roughness Ra(i) in the region other than the peripheral region is at least 0.2 µm and at most 1.2 µm. And, the ratio of Ra(i) to Ra(b) (Ra(i) / Ra(b)) is more than 1 and at most 4. Here, the surface roughness Ra (b) and the surface roughness Ra(i) are arithmetic mean roughness values and determined by an optical and laser-based non-contact three-dimensional profile measuring device in accordance with a German standard 'DIN-4768'.