Study On The Influence Of Cathode Catalytic Layer Wetting Characteristics On ?DMFC Performance

In an era where energy issues are highly concerned,the Micro Direct Methanol Fuel Cell(?DMFC),which has the advantages of high efficiency,environmental protection,portability,simple structure,and easy energy availability,has attracted widespread attention and the study.However,there are still many difficulties in achieving commercialization of ?DMFC,such as water management issues and catalyst catalytic activity issues.This paper focuses on the wetting characteristics of the cathode catalyst layer,and establishes a two-dimensional mass transfer model to theoretically study the effect of the cathode catalyst layer structure on the performance of the?DMFC.In this paper,cathode catalytic layers with different structures are prepared,and their effects in the battery system are tested and analyzed through experiments.In this paper,a two-dimensional two-phase mass transfer mathematical model of?DMFC is established to analyze the internal mass transfer of the battery,and verify the effect of the cathode catalytic layer structure on the mass transfer of the battery.According to the simulation results,the hydrophilic cathode catalyst layer can inhibit the water penetration phenomenon and reduce the concentration of water in the cathode diffusion layer.This structure is conducive to oxygen mass transfer and can also reduce methanol crossover.On the other hand,the structure of the cathode catalytic layer with less porosity can inhibit water penetration and methanol crossover,and improve the water management of ?DMFC.On the basis of theoretical simulation,a nitrogen-doped carbon material with hydrophilic properties was prepared in this paper.XPS test results showed that the carbon material fired at 200? had the highest nitrogen content;The catalyst is prepared by using carbon powder and nitrogen-doped carbon materials with different wetting characteristics as the carrier.The electrochemical test results show that the catalytic performance of the catalyst using the nitrogen-doped carbon material as the carrier is better than the traditional catalyst using carbon powder as the carrier,and the catalytic activity of the catalyst increases with the increase of nitrogen content;The catalyst was made into a cathode catalytic layer with a different structure,and the ?DMFC battery was tested.The results showed that the performance of the hydrophilic catalytic?DMFC was improved,and the ?DMFC with a smaller catalytic layer porosity had higher performance.