Preparation And Characterization Of Alkaline Composite Anion Exchange Membrane

Recently, alkaline anion exchange membrane fuel cells(AEMFCs) have triggered great attention due to the advantages of the lowered fuel ‘crossover’, high efficiency, and simplified water management. Anion exchange membranes(AEMs)are the critical component of AEMFCs. At present, AEMs have the drawbacks of(i)low OH- conductivity and(ii) poor stability. To this end, in this study, we propose to fabricate transport highways in membrane by introducing inorganic or organic material into membrane matrix, to enhance the OH- conductivity. At the same time,with the help of the mutual interference of the two materials, the structural stability is improved, which in turn endow AEMs with conductive stability. The main research content including:(1) The synthesis of imidazolium-functionalized graphene oxide(Im GO) nanosheets via distillation-precipitation polymerization is achieved. And the preparation of composite membrane based on CS. The hydroxide ion conductivity are characterized. At the same time, the influence of the property of side chain of imidazole ring on the conduction of nanohybrid membrane is also studied.Im GO could construct continuous transfer pathway for hydroxide ion in the membrane, endowing Im GO-filled polymer electrolyte membranes with excellent conduction properties. Composite membranes show better stability and conductivity. The optimal performance(CS/E-Im GO-2.0) shows the conductivity of 1.02×10-2 S cm-1 at 90 ℃, 100% RH, four times of that of CS control membrane(2.51×10-3S cm-1).(2) The design and synthesis of imidazolium polymer brushes grafted graphene oxide(AIm GO) via a facile atom transfer radical polymerization(ATRP) technique and the preparation of PVA based composite membranes are achieved. It is found that imidazolium polymer brushes grafted on AIm GOs show good compatibility with PVA chain, constructing continuous hydroxide ion transfer pathway in the membrane. And the imidazolium polymer brushes can insert into PVA matrix, which immensely facilitates the OH- transfer between polymer matrix and AIm GOs. The results show that composite membranes filled with longer polymer brushes grafted GO have excellent conduction property.PVA/EL-AIm GO-2.0 achieved the highest OH- conductivity of 6.01×10-2 S cm-1at 80 ℃(100% RH), with an enhancement of 191.7% compared to that of PVA control membrane(3.16×10-2 S cm-1).(3) The preparation of PVA-NF and PVA&CS-NFIL nanohybrid nanofibers via electrostatic spinning is achieved. And then, the hole of nanohybrid nanofibers is filled with the casting membrane solution of CS and PVA, respectively. By doing this, we try to study the influence of the fibrosis of polymer on the physical and chemical properties and OH-conduction properties. The results show that nanohybrid nanofiber membranes achieve better OH- conduction properties than CS or PVA control membrane. CS/PVA&CS-NF and PVA/PVA&CS-NF achieve the conductivities of 5.18×10-2S cm-1and 5.52×10-2S cm-1, respectively, under80 ℃, 100% RH.