Sulfonated Poly(Ether Sulfone) Ketone/ZrSPP Medium Temperature Composite Proton Exchange Membrane

Direct methanol fuel cell(DMFC) has attracted more attention,in virtue of their high-energy efficiency,low emission,in addition,methanol is abundant and is easy to transportation and storage.Key technology issues of DMFCs are the low catalytic activity and high methanol crossover.The effective way to solve the impendance is to raise fuel cell operation temperature.Elevated temperature can retard catalyst poisoning by adsorbed CO,enhance methanol oxidation rate and reduce methanol permeability,as a result,greatly improve the performance of the fuel cell.Thus new materials are required to improve the performance of DMFCs.Sulfonated poly(phthalazinone ether sulfone)(SPPES),sulfonated poly(phthalazinone ether sulfone ketone)(SPPESK) was prepared by reaction of fuming sulfuric acid with poly(phthalazinone ether sulfone)(PPES), poly(phthalazinone ether sulfone ketone)(PPESK).Because the swelling degree of SPPES and SPPESK is larger at medium temperature,they are not suitable for PEMFC,at medium temperature(130～180℃).Nanopartical ZrSPP,which has high proton conductivity at medium temperature,was synthesized,and the process parameters were explored.Structure and crystal texture of ZrSPP were characterized by XRD and TEM.The result showed that the ZrSPP had layer structure,with a diameter of hundreds of nanometer.Proton conductivity of ZrSPP was determined in the range of 20～180℃, at RH100%,was 10^-1S·cm^-1.The composite membranes were prepared by blending different mass ZrSPP with SPPES or SPPESK.The characterization of composite membrane was by SEM,FI-IR and TG-DTA,the results suggested ZrSPP homogeneous dispersed in SPPES,network structure and the hydrogen bond have formed between ZrSPP and SPPES;-HSO₃ was off at 200℃.Addition of ZrSPP was in favor of increasing proton conductivity at high temperature.Moreover, ZrSPP was in favour of reducing the swelling and methanol permeability of the composite membranes,and improving their thermal stability.To impove the mechanical performance of the composite membranes,PTFE porous membrane,which has good flexility,was to be used as a supporting layer. PTFE supported membranes have sandwich structure,and the polymer and ZrSPP layer adhere to the PTFE layer,as a result,impoving mechanical performance and flexility,and reducing the deformability of membranes,at high temperature.