Study On The SPEEK/HPW@SiO₂ Composite Proton Exchange Membrane

Sulfonated polyetheretherketone（SPEEK）still has many defects in the study of proton exchange membranes:low sulfonation degree（DS）,the conductivity is very low;under high sulfonation degree,excessive water absorption,film swelling.These characteristics affect the performance of the SPEEK membrane,which in turn affects the performance of the entire fuel cell.To solve this problem,a"proton conductor"-phosphotungstic acid（HPW）is doped into the SPEEK matrix to ensure that the SPEEK has a higher conductivity at the appropriate degree of sulfonation.However,since HPW is highly soluble in water and easily lost in the membrane,anchoring of HPW in the membrane has become a research hotspot.In this paper,（1）petal-like mesoporous silica（denoted as MSNs and K-MSNs）;（2）rod-shaped and spherical mesoporous silica molecular sieves（denoted as r-SiO₂,s-SiO₂,and K-r-SiO₂,K-s-SiO₂,respectively）before and after KH550 modification are introduced into the SPEEK matrix proton exchange membrane for anchoring HPW.The properties of the composite membranes are studied,including the water uptake,the dimensional stability,the proton conductivity,the conductivity stability and the effects of the KH550 modification of the nanoparticles on the properties of the composite membranes.The results show that（1）the proton conductivity of SPEEK/HPW@MSNs-0.5composite membrane is higher 26.8%than pure SPEEK membrane.The proton conductivity decreased by 15.10%after 240 h at 60℃and was 1.9 times lower than that of the SPEEK/HPW membrane.After amino modification,the performance of the SPEEK/HPW@K-MSNs-x composite membranes are superior to that of SPEEK/HPW@MSNs-x composite membranes.（2）In the molecular sieve composite membranes,the proton conductivity of the SPEEK/HPW@r-SiO₂-0.5 composite membrane and the SPEEK/HPW@s-SiO₂-0.5 composite membrane are higher 27.0%and 19.0%than SPEEK membrane,respectively.After amino modification,the conductivity stability of the SPEEK/HPW@K-r-SiO₂-1.0 composite membrane and the SPEEK/HPW@K-s-SiO₂-1.0 composite membrane are higher 50.7%and 28.1%than SPEEKmembrane,respectively.The proton conductivity of the two composite membranes decreased by 3.5%and 13.7%after 240 h at 60℃.In addition,after the addition of mesoporous silica,the water uptake of the composite membranes is significantly increased.