Fuel Cell Catalyst Composite for Low Humidity Operation
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Solution Overview
Problem
Conventional polymer electrolyte fuel cells using carbon-based carriers suffer from deterioration due to water, leading to decreased power generation performance, and there is a need to maintain performance under low humidity conditions without significant voltage decrease.
Innovation Solution
A method for operating a fuel cell using a cathode with a specific oxygen reducing catalyst, comprising composite particles with metal elements like titanium, carbon, nitrogen, and oxygen, and supplying the cathode with a low-humidified oxidizing agent gas, while maintaining the anode with a fuel gas, to prevent voltage decrease.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If carbon-based carrier is used to support catalyst in fuel cell, then catalyst supporting performance is improved, but carrier undergoes oxidative corrosion in presence of water during repeated start-stop operation, leading to deterioration and decreased power generation performance
Solution Approach 1:
The patent uses a composite carrier comprising carbon and metal oxide (such as titanium oxide, aluminum oxide, or silicon oxide) to support the catalyst. This composite structure combines the high surface area and conductivity of carbon with the water resistance and high potential stability of metal oxide, preventing oxidative corrosion during repeated start-stop operations while maintaining catalyst supporting performance.
2Reliability
If feed gas is humidified to allow solid polymer electrolyte membrane to exhibit sufficient proton conductivity, then proton conductivity is improved, but system size increases due to installation of humidifier
Solution Approach 1:
The fuel cell system is designed to generate water during operation through the electrochemical reaction, and this internally generated water is utilized to maintain the humidity of the feed gas and the proton conductivity of the membrane. This self-service approach eliminates or reduces the need for external humidifiers, thereby maintaining proton conductivity without increasing system size.
3Device complexity
If feed gas is supplied under low humidity conditions to simplify humidifier control system or eliminate humidifier, then device complexity is reduced, but voltage decreases compared to high humidity operation
Solution Approach 1:
The composite carrier comprising carbon and metal oxide maintains catalyst activity and stability under low humidity conditions, enabling the fuel cell to operate at high voltage without requiring a humidifier control system. The metal oxide component provides water resistance and structural stability that preserves power generation performance even when feed gas humidity is low.
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 method allows for high-performance fuel cell operation with superior initial voltage and start-stop durability, even under low humidity conditions, and is more cost-effective than using platinum-supporting carbon catalysts.
Implementation Method 1
a layer containing a catalyst has been conventionally disposed on the surface of the cathode or the surface of the anode of the fuel cell. As the catalyst, a noble metal such as platinum has been primarily used.
Implementation Method 2
oxygen is reduced at the cathode to produce electricity
Implementation Method 3
composite particles, the composite particles being particles in which primary particles of a compound of a metal element M1 are dispersed in a structure composed of carbon
Implementation Method 4
supplying the cathode with an oxidizing agent gas which comprises an oxygen gas
Implementation Method 5
a fuel is supplied to the anode, and oxygen or air is supplied to the cathode, whereby oxygen is reduced at the cathode to produce electricity
Data Source
Figure 1~2(c)
Figure 3~4
AI summary
Provided is a method for operating a fuel cell involving supplying an electrode with a low or non-humidified gas that achieves no significant decrease of voltage as compared with when a high-humidified feed gas is used. The method for operating a fuel cell having a membrane electrode assembly includes a cathode, an anode and an electrolyte membrane interposed between both the electrodes, wherein the cathode has a layer including an oxygen reducing catalyst including composite particles which include atoms of a metal element M1, carbon, nitrogen and oxygen and in which primary particles of a compound of the metal element M1 are dispersed in a carbon structure, which method includes supplying the cathode with an oxidizing agent gas which includes an oxygen gas and which has a relative humidity at a temperature of the membrane electrode assembly of 60% or less, and supplying the anode with a fuel gas.