Fuel Cell Catalyst Carrier Resistance for Reverse Current Prevention
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Solution Overview
Problem
In fuel cell systems, the degradation of cathode catalysts occurs due to the presence of air in the fuel gas channel during restart, leading to reverse current and catalyst corrosion, as air mixes with residual fuel gas, causing undesired chemical reactions and pressure leaks.
Innovation Solution
A fuel cell system with a catalyst anode carrier material that exhibits higher electric resistance in an oxygen-containing atmosphere than in a hydrogen atmosphere, along with a control device that consumes fuel gas and introduces oxygen-containing gas into the fuel gas chamber during stoppage and restart, preventing reverse current generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If air is used to purge the fuel gas chamber, then nitrogen facility is not required and operability is improved, but residual air remains in the fuel gas channel causing cathode catalyst degradation
Solution Approach 1:
The system performs preliminary action by consuming residual fuel gas in the fuel gas channel before introducing air for purging. The control device activates the fuel cell in a fuel-consuming mode to deplete hydrogen, then introduces air to replace the fuel gas, preventing air-fuel mixture formation and subsequent reverse current that would degrade the cathode catalyst.
Solution Approach 2:
The fuel cell operates continuously in a fuel-consuming mode during the transition from fuel gas to air, maintaining useful electrochemical reactions to deplete residual hydrogen. This continuous fuel consumption action ensures that when air is introduced, no fuel gas remains to form harmful mixtures, thus protecting the cathode catalyst while maintaining system productivity.
2Productivity
If fuel gas is supplied to restart the fuel cell from purged state, then the fuel cell can be restarted, but air remains in the downstream portion of the fuel gas channel causing reverse current
Solution Approach 1:
Before restarting fuel gas supply, the system performs preliminary fuel consumption to deplete any residual air-fuel mixtures in the channel. The control device activates the fuel cell to consume fuel, ensuring that when fresh fuel gas is supplied for restart, the channel contains only inert or safe gas compositions, preventing reverse current generation.
Solution Approach 2:
The system uses an intermediary process of controlled fuel consumption and air introduction to transition the fuel gas channel from purged state to operational state. This intermediary action ensures that air and fuel gas do not coexist in the channel during restart, eliminating the condition for reverse current while maintaining restart capability.
3Power
If the anode catalyst carrier has low electric resistance in oxygen atmosphere, then electron propagation is efficient, but reverse current occurs due to proton transfer resistance
Solution Approach 1:
The invention changes the electric resistance parameter of the anode catalyst carrier based on the atmospheric conditions. The carrier material is designed to exhibit high electric resistance specifically in oxygen-containing atmospheres, which suppresses electron propagation and prevents the electrochemical reactions that lead to reverse current, while maintaining low resistance in hydrogen atmospheres for efficient power generation.
Solution Approach 2:
The anode catalyst carrier exhibits different electrical properties in different atmospheric environments. The material is engineered to have high electric resistance specifically when exposed to oxygen, creating a localized property change that prevents reverse current only when needed, while maintaining normal conductive properties during fuel cell operation in hydrogen atmosphere.
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 solution effectively inhibits reverse current and reduces catalyst degradation by ensuring minimal air ingress into the fuel gas channel, thereby prolonging catalyst lifespan and maintaining system performance.
Implementation Method 1
a catalyst used for an anode, wherein a carrier of the catalyst is composed of a material with a property where electric resistance in an oxygen containing atmosphere is greater than electric resistance in a hydrogen atmosphere
Implementation Method 2
a fuel cell having a catalyst used for an anode
Implementation Method 3
introducing oxygen containing gas into the fuel gas chamber
Data Source
AI summary
A fuel cell system and a method of operating the same is provided that is capable of reducing degradation of a cathode catalyst of a fuel cell. A fuel cell system is provided that includes a fuel cell having a catalyst used for an anode, wherein a carrier of the catalyst is composed of a material with a property where electric resistance in an oxygen containing atmosphere is greater than electric resistance in a hydrogen atmosphere; and a control device configured to control the fuel cell, when supply of fuel gas is stopped during stoppage of operation of the fuel cell, to consume all or part of the fuel gas in a fuel gas chamber, followed by introducing oxygen containing gas into the fuel gas chamber.