Preparation And Properties Of Poilionic Liquid /polybenzimidazole High Temperature Proton Exchange Membrane

High temperature proton exchange membrane fuel cell（HT-PEMFC）can convert chemical energy of hydrogen fuel into electric energy through electrochemical reaction,which is an effective way to realize efficient and green utilization of hydrogen energy.Phosphoric acid-doped polybenzimidazole（PA-PBI）membrane is considered to be one of the most promising high-temperature proton exchange membrane materials due to its good thermal stability,mechanical strength and proton conductivity.However,PA-PBI membrane has excellent proton conductivity only at high phosphoric acid doping content.High amount of doped phosphate can cause the loss of membrane and a big drop in phosphoric acid on the mechanical properties of the attenuation,makes the membrane performance and ionic liquid insurance-linked securities because of its wide electrochemical window,non-volatile and thermal stability is good wait for a characteristic,therefore the ionic liquids as extra proton conductors to the preparation of the performance of proton exchange membrane has important research significance.However,ionic liquid loss and low proton transfer rate still exist.How to prepare membrane materials with high proton conductivity and stability is a challenging problem for PA-PBI high-temperature proton exchange membrane.In this work,aromatic ether polybenzimidazole（OPBI）was used as the framework polymer to design and synthesize ionic liquids with different structures,and optimize the effect of ionic liquid doping on the properties of opbi films;further polymerize the ionic liquid,adjust the polymerization degree of polyionic liquid,and construct the ionic liquid with macromolecular structure,so as to reduce the loss of ionic liquid and improve the stability of membrane at the same time.The main contents and conclusions of this paper are as follows:（1）[Vi Et Im]Br and[HVIM]H₂PO₄ ionic liquids were synthesized by alkylation and acid-base neutralization methods,and ILs-Br/OPBI,ILs-H₂PO₄/OPBI membranes were prepared to study the influence of the doping amount of the two ionic liquids on the properties of OPBI membranes.The results show that the ILs-H₂PO₄/OPBI blend membrane with 15%ionic liquid doping has the best comprehensive performance,the phosphoric acid doping level（ADL）is as high as 16.5,and the proton conductivity can reach 64.6 m S/cm without humidification at 180℃,which is 1.9 times that of the original opbi membrane and 1.3 times that of 15%-ILs-Br/OPBI membrane.（2）Three polyionic liquids P[HVIM]H₂PO₄ with different intrinsic viscosities(0.59,1.27 and 2.34 d L·g^-1)were synthesized.The properties of PILs-H₂PO₄/OPBI blend membrane were investigated under the condition of 15%ionic liquid doping.The results show that the increase of intrinsic viscosity can improve the comprehensive properties of the membrane.The polyionic liquid blend membrane（2.34-PILs-H₂PO₄/OPBI）with an intrinsic viscosity of 2.34 d L·g^-1 has the highest proton conductivity（113.9 m S/cm）at 180℃,which is 3.5 times that of the original OPBI membrane.After soaking in water for 100 min,the ionic liquid loss rate is 16.1%,which is half of the ILs-H₂PO₄/OPBI membrane without polymerization modification,showing excellent ionic liquid doping stability.（3）After the OPBI membrane,0.59-PILs-H₂PO₄/OPBI membrane,1.27-PILs-H₂PO₄/OPBI membrane and 2.34-PILs-H₂PO₄/OPBI membrane were immersed in Fenton reagent for 96 hours,the 2.34-PILs-H₂PO₄/OPBI membrane had the lowest mass loss rate（6.7%）,and after Fenton reagent oxidation treatment for 50 hours,ADL decreased by only 5%,and proton conductivity decreased by 10%at 180℃;compared with OPBI membrane,ILs-H₂PO₄/OPBI and other PILs-H₂PO₄/OPBI membranes,2.34-PILs-H₂PO₄/OPBI membrane has excellent oxidation stability.