Stability Of Membrane Electrodes Assembly For Anion Exchange Membrane Fuel Cells

With the intensification of the global greenhouse effect,reducing carbon emission has become the most important task for the protection of the environment.Our country has also made the goals of"carbon peak"and"carbon neutralization".The use of fossil energy is the main component of carbon emissions,and fossil energy is a non-renewable energy,continuous consumption will inevitably lead to energy crisis.Therefore,finding clean energy that can replace fossil energy is one of the effective solutions to reduce carbon emissions,reduce greenhouse effect and alleviate energy crisis.As a clean and pollution-free energy,hydrogen energy has become a new energy vigorously supported by the current state due to its large reserves,high calorific value and pollution-free characteristics.Fuel cell as the main application form of hydrogen energy,its high efficiency,safety and other characteristics make it popular.At present,the development of proton exchange membrane fuel cells is becoming more and more perfect.New energy vehicles powered by proton exchange membrane fuel cells have been launched successively,and their performance is not on par with that of internal combustion engine vehicles.However,their cars are generally more expensive than those with internal combustion engines,because proton exchange membrane fuel cells are limited to precious metal catalysts,which makes them expensive.In order to reduce the cost,anion exchange membrane fuel cells,which can use non-expensive catalysts,come into the field of researchers and develop rapidly.At present,its performance has made a great breakthrough,but its stability（the battery running time when the voltage is reduced to 90%of the initial stable voltage）is not satisfactory,which restricts the commercialization process of anion exchange membrane fuel cells.This paper focuses on water management,catalyst support and other factors that have important effects on the stability of anion exchange membrane fuel cells.The specific contents are as follows:（1）To explore the influence of water management on the stability of anion exchange membrane fuel cells.The water management was optimized by optimizing the catalyst slurry and experimental conditions,adjusting the hydrophilicity,hydrophobicity and humidification degree of the membrane electrode.By adjusting the amount of alkaline ionomer PAP-TP-100,adding hydrophobic substances PTFE and Nafion,changing the inlet speed and back pressure of the yin-yang bipolar gas,the water management of the battery was improved,and the stability of the fuel cell was obviously enhanced.It was found that under the experimental conditions of low gas velocity and no back pressure,the mass ratio of the ionomer to carbon was 1.25,and the catalyst mass of 10 wt.%PTFE was added,the battery water management state was better,and the voltage attenuation time of the fuel cell was increased from the initial 30 h to 130 h by 10%.The voltage drop is reduced from the initial 2.30m V/h to 0.53 m V/h.（2）To explore the influence of carbon carrier on the stability of anion exchange membrane fuel cells.Pt nanoparticles were synthesized by colloidal method and supported on different carbon supports to prepare a series of Pt/C catalysts with Pt content of 40 wt.%and different carbon supports.The series of catalysts showed similar and good Oxygen reduction reaction（ORR）activity in the three-electrode system.At 0.9 V,the mass activity was more than 0.2 A/mg _Pt and the area activity was more than 0.8 m A/cm _Pt².Therefore,it can be considered that the main difference of the catalyst was only from the carbon support.Using this series of catalysts,the same formula was used to prepare fuel cell membrane electrodes.The accelerated aging test of fuel cells was carried out and compared with the commercial 40 wt.%Pt/C catalyst.Combined with a series of characterization,the influence of catalyst carbon carrier on the stability of fuel cell membrane electrodes was explored.The results show that the carbon carrier with high hydrophobicity and electrochemical oxidation resistance can effectively improve the water management of the cell and enhance the performance and stability of the fuel cell.