Ceramic Porous MEA Electrodes via Low-Temperature Ammonolysis
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Solution Overview
Problem
Current methods for producing membrane electrode assemblies (MEAs) for proton ceramic fuel cells (PCFC) and electrolyser cells (PCEC) face challenges in forming stable metal (oxy)nitride electrodes at low temperatures due to interreaction with proton ceramic phases, limiting the use of high Ce content compositions that offer high proton conductivity.
Innovation Solution
A low-temperature method involving the direct conversion of soluble transition metal oxalate precursors to metal (oxy)nitride phases using ammonolysis in an ammonia-containing gas, avoiding interreaction and enabling the formation of stable metal (oxy)nitride electrodes for MEAs, specifically using ammonium transition metal oxalates and ammonolysis at temperatures below 800°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional high-temperature methods are used to form metal (oxy)nitride electrodes, then good adhesion between layers is achieved, but interreaction between the metal (oxy)nitride electrode and proton ceramic components occurs, compromising phase integrity
Solution Approach 1:
The patent changes the temperature parameter from conventional high-temperature processing (>800°C) to low-temperature processing (500-800°C). This parameter change resolves the contradiction by enabling good adhesion at lower temperatures through the specific low-temperature sintering process, thereby preventing interreaction between metal (oxy)nitride and proton ceramic components while maintaining phase integrity.
Solution Approach 2:
The patent applies preliminary action by using a sol-gel derived precursor coating that is applied to the proton ceramic substrate before final sintering. This precursor layer serves as an intermediate that facilitates adhesion at low temperatures and prevents direct interreaction between the metal (oxy)nitride and proton ceramic components during the sintering process.
2Reliability
If high Ce content compositions are used in the proton ceramic phase, then high proton conductivity is achieved, but interreaction with metal (oxy)nitride increases at conventional processing temperatures
Solution Approach 1:
The patent changes the temperature parameter to low-temperature processing (500-800°C), which resolves the contradiction by enabling the use of high Ce content compositions (providing high proton conductivity) without causing interreaction with metal (oxy)nitride. The low temperature prevents the harmful interreaction while preserving the desired high proton conductivity of the high Ce content ceramic phase.
3Stability of the object's composition
If low-temperature processing is used to prevent interreaction, then phase integrity is maintained, but adhesion between layers becomes insufficient
Solution Approach 1:
The patent applies preliminary action by depositing a sol-gel derived precursor coating onto the proton ceramic substrate before sintering. This precursor layer is specifically designed to facilitate adhesion at low temperatures and to prevent direct contact between metal (oxy)nitride and the proton ceramic phase, thereby resolving the adhesion issue at low temperatures while maintaining phase integrity.
Solution Approach 2:
The patent introduces an intermediary layer derived from the sol-gel precursor that acts as a mediator between the metal (oxy)nitride and the proton ceramic substrate. This intermediary layer enables adhesion at low temperatures without causing interreaction, thus resolving the contradiction between adhesion strength and phase integrity.
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 method allows for the production of stable metal (oxy)nitride electrodes that maintain phase integrity and high proton conductivity, facilitating the use of high Ce content compositions for efficient electrochemical reactions at lower temperatures.
Implementation Method 1
A low-temperature method involving the direct conversion of soluble transition metal oxalate precursors to metal (oxy)nitride phases using ammonolysis in an ammonia-containing gas
Implementation Method 2
The ceramic membrane of the MEA allows the separation of gaseous reactants at the electrode sides, being permeable only to protons
Implementation Method 3
a Proton Ceramic Fuel Cell (PCFC), created by single or repeat units of the MEA, performs the electrochemical oxidation of a fuel to directly produce electricity and heat
Data Source
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AI summary
The present disclosure relates to a membrane electrode assembly, and his method for fabrication. It is disclosed a ceramic porous electrode for a membrane electrode assembly comprising a metal(oxy)nitride impregnated on the electrode structure.