Study On The Preparation And Modification Of Membrane Electrode Materials For Alkaline Polymer Electrolyte Fuel Cells

Contradiction of large energy supplying and pressures of environmental pollution make us aware of the importance and urgency of protecting the environment and conserving ecological resources in China.Therefore,we must save energy,protect the environment,and work hard to find energy technologies that are sustainable and less polluting the environment,so as to alleviate the pressure caused by energy shortages.Fuel cells can directly convert chemical energy into electrical energy through electrochemical reaction,and the high energy conversion efficiency,which has attracted people’s attention.Unlike other types of fuel cells,electrolyte of polymer dielectric fuel cells is polymer polymerization（ion-exchange membranes）that conduct H⁺/OH⁺ ions selectively.Membrane Electrode Assembly（MEA）is a key component of polymer electrolyte fuel cells.The anode catalyst and anion exchange membrane are important components of MEA,which determine the efficiency of the battery largely.In this paper,the anode catalyst and anion exchange membrane were studyed to improve their performance.Carbon black as the supporter of catalysts was oxidized by KMnO₄.The anode catalyst Pd₁Ni₁/AC_x（x=3,5,7）is prepared is prepared by precipitating co-reduction method.Among them,the Pd loading（mass fraction,the same below）of Pd₁Ni₁/AC₅ is the largest（3.66%）,the average particle size of Pd grains is the smallest（4.71 nm）,and it is evenly distributed on the carbon carrier after oxidation treatment of KMn04.There are many active sites;XRD shows that Ni in all three Pd₁Ni₁/AC_x catalysts are present in amorphous form.In the electrochemical performance test,all three catalysts showed better electrochemical stability and survival than commercial Pd/C;Pd₁Ni₁/AC₅ electrochemically active surface area was as high as 62.21 m²/gPd,and ethanol oxidation activity is 1791.85 mA/mgPa.In this paper,dimethyl sulfoxide（DMSO）was used as a solvent to prepare three membranes:PVDF membrane,PVDF/PVA membrane and PVDF/PVA-TiO2 composite membrane.And the membrane structure and hydrophilicity,swelling ratio,electrical conductivity,etc.were characterized.The experimental results show that compared with pure PVDF membranes,the PVDF/PVA membranes exhibit more interface micropores,contact angle is smaller and the hydrophilicity is higher;compared with PVDF/PVA membrane,contact angle of PVDF/PVA-TiO₂ composite membrane reduced significantly,pore surface porosity reduced and the ethanol permeability coefficient is 1.045 × 10^-8 cm²/s.The ratio of the Nafion membrane is reduced by two orders of magnitude by 1.53 × 10^-6 cm²/s,showing better alcohol resistance.