Preparation And Application Of SPSF Composite Proton Exchange Membrane Modified By Special-shaped Alumina Nanofiber

As the core component of direct methanol fuel cell,the quality of proton exchange membrane directly determines the operation performance and service life of fuel cell.At present,the common problem restricting the development of commercial Nafion membrane and non fluorosulfonic acid polymer membrane is that there is an obvious trade off effect between proton conductivity and methanol permeability.In order to solve the above problems,we successfully prepared two kinds of special-shaped alumina Nanofibers:porous alumina nanofibers（PANFs）and spiny alumina nanofibers（SANFs）by adjusting the content of pore forming agent in spinning solution and combining electrostatic solution blowing technology and heat treatment process.After functionalization,they were introduced into sulfonated polysulfone（SPSF）matrix as an additive to prepare modified SPSF composite proton exchange membrane.To explore the effects of alumina nanofibers with different chemical components and different physical structures on the properties of composite proton exchange membrane,so as to provide research ideas for the development of high-performance proton exchange membrane with synchronous improvement of proton conduction and methanol barrier properties.The main research contents are as follows:（1）Porous alumina nanofibers（PANFs）were prepared by electrostatic solution blowing（EBS）and calcination process.PANFs and PANFs-NH₂were introduced into SPSF matrix respectively,and modified SPSF composite proton exchange membranes（PANFs/SPSF and PANFs-NH₂/SPSF）were obtained by tape casting.The long-range continuous structure of alumina nanofibers provides a large number of transfer carriers and conduction paths for proton transfer.At the same time,the rich pores of PANFs provide a large number of vertical transfer channels at the interface between PANFs and polymer matrix.These stable vertical channels promote vertical proton conduction and improve the proton conductivity of composite membranes.The experimental results show that the proton conductivity of PANFs-NH₂/SPSF composite membrane is 0.237 S cm^-1（80℃,100%RH）.At the same time,the methanol barrier performance has also been improved to a certain extent.（2）Uniform and continuous spiny alumina nanofibers（SANFs）were successfully prepared by adjusting the content of polytetrafluoroethylene（PTFE）in spinning solution and the calcination temperature during heat treatment.SANFs-NH₂is obtained after functionalizing SANFs.SANFs and SANFs-NH₂were introduced into SPSF matrix as functional additives to obtain SANFs/SPSF and SANFs-NH₂/SPSF composite membranes.Thanks to the advantage of spiny structure and the effect of acid-base pair（-SO₃H...-NH₂）,the horizontal and vertical proton transfer sites in SANFs-NH₂/SPSF composite membrane increase,the proton transfer anisotropy decreases,and the proton conductivity is as high as 0.263 S cm^-1（80℃,100%RH）.At the same time,the interfacial compatibility between nanofibers and polymer matrix was enhanced,and the methanol permeability decreased to 4.18×10^-7cm²s^-1.The proton conductivity and alcohol resistance of the composite proton exchange membrane have been improved,which provides a reference for the construction of low-cost and high-performance proton exchange membrane.