Bilayer Diffusion Barrier for Solid Oxide Cell Stability
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Solution Overview
Problem
Solid oxide fuel cells and electrolysis cells face degradation due to chemical reactions between the air electrode and zirconia-based electrolyte layers, leading to increased resistance and instability, particularly because ceria-based diffusion barrier layers require high-temperature sintering, which can cause chemical reactions with zirconia-based electrolytes and result in porous structures that allow element diffusion.
Innovation Solution
A bilayer diffusion barrier layer is formed using a sintered ceria-based metal oxide with and without a sintering aid, where the first layer contains nanopowder and macropowder, and both layers are sintered together at a temperature of 1000-1250°C to achieve high bonding strength and prevent secondary phase formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ceria-based diffusion barrier layer is formed to prevent chemical reaction between air electrode and zirconia-based electrolyte, then chemical stability is improved, but sintering temperature must be increased to 1400°C or higher to achieve densification
Solution Approach 1:
The patent introduces a sintering aid (metal oxide such as CoO, Fe2O3, NiO, ZnO, CuO, MnO, or Li2O) to change the sintering parameters of the ceria-based diffusion barrier layer, enabling densification at reduced temperatures of 1250°C or lower while maintaining chemical stability and preventing element diffusion between layers
Solution Approach 2:
The patent creates a composite material system by combining ceria-based metal oxide with a sintering aid, forming a multi-component diffusion barrier layer that achieves both low-temperature sinterability and effective diffusion prevention, resolving the contradiction between sintering temperature and chemical stability
2Reliability
If sintering temperature is reduced to 1250°C or lower to prevent chemical reaction with zirconia-based electrolyte, then chemical stability is improved, but densification degree is degraded and significant pores are formed
Solution Approach 1:
The patent modifies the sintering parameters by adding a sintering aid that lowers the sintering temperature to 1250°C or lower while simultaneously improving densification degree and reducing pore formation, achieving both chemical stability and manufacturing precision
Solution Approach 2:
The sintering aid acts as an intermediary substance that facilitates densification at low temperatures by promoting particle bonding and reducing porosity, enabling the diffusion barrier layer to achieve high densification without chemical reaction with the electrolyte
3Manufacturing precision
If sintering is performed at high temperature to achieve densification of ceria-based material, then densification degree is improved, but chemical reaction with zirconia-based electrolyte occurs
Solution Approach 1:
The patent changes the sintering temperature parameter from high temperature (1400°C or higher) to reduced temperature (1250°C or lower) by introducing a sintering aid, achieving both densification and chemical stability simultaneously
Solution Approach 2:
The sintering aid serves as a protective intermediary that enables densification to occur at lower temperatures, preventing direct contact and chemical reaction between the ceria-based diffusion barrier layer and the zirconia-based electrolyte while still achieving adequate densification
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 solution effectively inhibits the diffusion of elements from the air electrode to the electrolyte, improving the efficiency and stability of solid oxide cells by preventing insulating reaction products and maintaining a dense structure at lower sintering temperatures.
Implementation Method 1
a diffusion barrier layer which includes a ceria-based metal oxide and a sintering aid
Implementation Method 2
both layers are sintered together at a temperature of 1000-1250°C to achieve high bonding strength
Data Source
AI summary
Provided is a solid oxide cell including a fuel electrode layer, electrolyte layer and an air electrode layer, wherein a diffusion barrier layer is provided between the air electrode layer and the electrolyte layer, the diffusion barrier layer includes: a first diffusion barrier layer formed on the electrolyte layer and including a sintered ceria-based metal oxide containing no sintering aid; and a second diffusion barrier layer formed on the first diffusion barrier layer and including a sintered product of a ceria-based metal oxide mixed with a sintering aid, the first diffusion barrier layer includes a sintered product of nanopowder and macropowder of a ceria-based metal oxide, and the first diffusion barrier layer and the second diffusion barrier layer are sintered at the same time. The diffusion barrier layer is densified, shows high interfacial binding force and prevents formation of a secondary phase derived from chemical reaction with the electrolyte.