Construction Of A Novel Type Of Proton Exchange Membrane With Three-dimensional High Surface Area,and Study On Fuel Cell Performance

Proton exchange membrane fuel cell?PEMFC?is considered as a promising green energy conversion technology due to its advantages,such as high energy conversion efficiency,quick startup at low temperature,and zero or low exhaust,etc.Membrane electrode assembly?MEA?is the key component of PEMFC.The electrochemical reaction mainly occurs in the membrane electrode assembly,so the good membrane electrode interface structure plays a key role in improving the performance of the membrane electrode assembly.Traditional membrane electrode assembly preparation method is simple and suitable for large-scale production,but it cannot establish a good three-phase interface,in which will cause concentration polarization and electrochemical polarization phenomenon.The multiphase mass transfer channel is in a disordered state,and the catalyst cannot be used effectively,which seriously restrict the fuel cell performance.By designing the the interface structure of the membrane electrode assembly,an orderly multiphase mass transfer channel can establish to reduce the polarization,increase the utilization rate of Pt catalyst and reduce the cost.It is extremely significant for the commercialization of PEMFC.In this paper,we prepared a three-dimensional porous surface structure membrane by spraying a pore-forming agent and Nafion solution onto the surface of the proton exchange membrane and studied its performance.The influence of species and ratio of the pore-forming agent and the Nafion solution,and thickness of the porous layer on the performance of three-dimensional porous membrane were studied.Firstly,Zinc Oxide,Magnesium Oxide,calcium carbonate and alkaline zinc carbonate were used as pore forming agents to prepare a proton exchange membrane with a three-dimensional porous structure possessing high specific area.The performance of porous fuel cell membrane electrode was investigated.It was found that using Zinc Oxide and Magnesium Oxide as pore forming agents can build a good three-dimensional porous structure.However,using calcium carbonate and alkaline zinc carbonate as pore-forming agent lead to no significant three-dimensional porous structure.Under a cell temperature of 70?,30 psi back pressure and 100%RH,the membrane electrode assembly of Zinc Oxide as a pore making agent can reach 600mA cm^-2 in 0.7V.Compared with the blank membrane electrode,there was a 100mA cm^-2 improvement.Secondly,using zinc oxide as the pore-forming agent and changing Nafion content in porous layer slurry to prepare three-dimensional porous proton exchange membrane with different porosity.The performance of porous fuel cell membrane electrode was investigated.It was found that when the ratio of Nafion?dry weight?to total weight is more than 1.1,the pore forming agent will accelerate the agglomeration,causing the porous layer to become inhomogeneous.Under a cell temperature of 70?,30 psi back pressure and 100%RH,the membrane electrode assembly prepared by the porous membrane with 5%Nafion?dry weight?was better than the other membrane electrodes assembly at 0.7V and the current density is700m A cm^-2.Finally,Changing the load of pore forming agent under optimal ratio to Nafion solution to prepare three-dimensional porous proton exchange membrane with various thickness.The performance of porous fuel cell membrane electrode is investigated.It was found that increasing pore forming agent load will not affect the preparation of porous layer.Under a cell temperature of 70?,30 psi back pressure and 100%RH,the membrane electrode assembly prepared by the porous membrane with Pore-forming agent loads of 0.4 mg cm^-2 has the best performance at0.7V,the current density is 700m A cm^-2 and the membrane electrode also has the maximum electrochemical activity specific surface area.