Research And Preparation On Passive Micro Direct Methanol Fuel Cell Cathode MEA

Direct methanol fuel cell (DMFC) has some advantages, such as relativelysimple structure, easy fuel carrying and storage, and high energy density, and hasvery broad application prospects. The membrane electrode assembly is the key ofdirect methanol fuel cell, therefore, making high performance membrane electrodeassembly has important implications for the development of DMFC. This papermainly studies the microporous layer and catalyst layer in the membrane electrodeassembly, and improving the performance of passive direct methanol fuel cells.This paper first introduces the working principle and structure characteristics ofpassive micro direct methanol fuel cell, and through the analysis of the internalstructure of the battery, optimizing the structure of the cathode microporous layer andcatalytic layer, and the test confirms the direct methanol fuel cell structure optimizedhas better performance.In the optimization of cathode microporous layer, cathode microporous layerswith different carbon loading were made, and we compared the cell performance,then selected the best carbon loading as parameter. On this basis, add differentpercentage content of teflon(PTFE) in the cathode microporous layer to change thehydrophobicity of the cathode microporous layer, the maximum power density of thebattery is27mW/cm2. Then, build different teflon gradient structure in the cathodemicroporous layer, research its effect on the battery performance, and the maximumpower density of the battery is31mW/cm2. Finally, add ammonium carbonate asporogen in the cathode microporous layer and change its percentage content, and themaximum power density of the battery is28mW/cm2.In the optimization of cathode catalyst layer, teflon was added in the cathodecatalyst layer in order to make hydrophobic catalytic layer, and we built up thegradient structure of different teflon concentration in the catalyst layer to study itseffect on the cell performance, the maximum power density of battery could reach35mW/cm2. On this basis, ammonium carbonate was used as porogen to optimize the cathode catalyst porosity, then we formed multilayer gradient structure ofhydrophobicity and porosity in the cathode catalyst layer, then we make absorbentlayer on the surface of the catalyst layer to improve water management and oxygenmass transfer in the cathode, and improve the performance of direct methanol fuelcell. The conclusions are as follows: the highest power density of passive directmethanol fuel cell, which used multi-layer hydrophobic gradient distribution ofcathode catalyst layer cell, is36mW/cm2; The maximum power density of passivedirect methanol fuel cell with the gradient distribution of both hydrophobicity andporosity is37mW/cm2; On this base, the highest power density of passive directmethanol fuel cell, which the SiO2absorbent layer was used, can be up to40mW/cm2. While in the same working condition, the maximum power density oftraditional passive DMFC can only reach27mW/cm2.