Spinel Transition Metal Oxide Bonding for Fuel Cell Interconnects
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Solution Overview
Problem
Existing methods for bonding conductive connecting members to electrodes in solid electrolyte fuel cell stacks face challenges with high temperature oxidation, insufficient sintering at lower temperatures, and high costs, leading to reduced bonding strength and reliability.
Innovation Solution
A method involving the use of transition metal oxides with a spinel structure, manufactured by mixing metal powders and subjecting them to heat treatment at relatively low temperatures, which accelerates sintering through self-heating oxidation, allowing for strong bonding without excessive oxidation or high costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heat treatment is performed at high temperature (1000°C or higher) to achieve sufficient bonding strength, then bonding strength is improved, but metal interconnector oxidation increases leading to increased contact resistance
Solution Approach 1:
The invention changes the temperature parameter from conventional high temperature (1000°C or higher) to a lower temperature range (700-950°C). This parameter change is made possible by using metal powder as starting material which undergoes oxidation reaction to generate heat, enabling sufficient sintering and bonding strength at lower temperatures while preventing excessive oxidation of the metal interconnector.
Solution Approach 2:
The metal powder serves a dual function: it acts as both the bonding agent material and the heat source through its oxidation reaction. The oxidation of metal powder generates heat that accelerates the sintering process, eliminating the need for external high-temperature heating and thereby preventing interconnector oxidation while achieving sufficient bonding strength.
2Object-affected harmful factors
If heat treatment is performed at low temperature (800-900°C) to suppress oxidation of metal interconnector, then oxidation is reduced, but bonding agent sintering is insufficient leading to reduced bonding strength
Solution Approach 1:
Metal powder is used as the starting material for the bonding agent, and its oxidation reaction during heat treatment provides self-heating that accelerates sintering. This self-generated heat enables sufficient bonding strength to be achieved at lower temperatures (700-950°C) where interconnector oxidation is suppressed.
Solution Approach 2:
The invention changes the heat treatment temperature from conventional low temperature (800-900°C) to an optimized range (700-950°C) and extends the heating time (1-12 hours). Combined with the self-heating effect from metal powder oxidation, this parameter change enables sufficient sintering without causing interconnector oxidation.
3Strength
If conventional bonding methods are used, then bonding can be achieved, but manufacturing cost increases due to use of expensive materials like silver
Solution Approach 1:
The invention replaces expensive materials like silver powder/silver alloy with metal powder (such as nickel, copper, or their alloys) as the starting material for the bonding agent. This substitution significantly reduces material cost while the oxidation reaction of the metal powder provides self-heating to ensure sufficient bonding strength.
Solution Approach 2:
The metal powder in the bonding agent serves dual purposes: it provides the bonding material and generates heat through oxidation reaction to accelerate sintering. This eliminates the need for expensive additives or external high-temperature heating systems, reducing overall manufacturing cost while maintaining bonding strength.
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 approach achieves high bonding strength and reduced variability, maintaining electrical conductivity while preventing oxidative deterioration, thus enhancing the reliability and efficiency of the fuel cell stack.
Implementation Method 1
a heat treatment is performed on the paste so that a transition metal oxide having a spinel structure is generated. When metal powders are used as starting materials, a sintering progress of the powder can be accelerated by self-heating along with the oxidation reaction in the metal powder during the heat treatment
Implementation Method 2
the sintering progress of the powder can be accelerated by self-heating along with the oxidation reaction in the metal powder during the heat treatment
Implementation Method 3
a heat treatment is performed on the paste so that a transition metal oxide having a spinel structure is generated... allowing for strong bonding without excessive oxidation or high costs
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
A novel method of manufacturing a transition metal oxide having a spinel structure is provided. A mixture of powdery metals of metal elements constituting the transition metal oxide is heated in an oxidizing atmosphere to generate the transition metal oxide.