Application Of Anion Exchange Membrane Based On Main Chain Ionic Polymer In Fuel Cell

As clean and reusable alternative energy source,fuel cells have the advantages of high conversion efficiency,low noise emission and fast load response,and have broad application prospects.Compared with all the fuel cells,the commercial prospects of alkaline anion exchange membrane fuel cells will be better than that of proton exchange membrane fuel cells,because relatively inexpensive catalyst can be available to save costs.As a key component in alkaline fuel cells,anion exchange membrane(AEM)has a significant impact on battery performance.Therefore,good electrical conductivity,excellent chemical stability,high mechanical strength,and moderate water uptake and swelling are particularly important for AEMs.In this paper,main chain pyrrolidinium and quaternary ammonium cations and their corresponding AEMs were synthesized and studied from the perspective of small molecules.The length of the alkyl chain and replacing different cations were investigated to improved their alkaline stability of main chain cations and their corresponding AEMs.The main conclusion in this dissertation are as follows:(1)A series of small molecules with mono/multi-pyrrolidinium cations tethered with different alkyl groups were successfully designed and synthesized.The increasing density of the pyrrolidinium cations boosted the alkaline stability,indicated by DFT calculations that adjacent pyrrolidinium cations lowered the charge density on the α-C in the pyrrolidinium group and enhanced the energy barrier for the attack of OH-.In addition,The synthesized cationic polymers,composed of pyrrolidinium cations showed good electrical conductivity,thermal stability and alkaline stability.(2)A series of small molecules with different types of cations were successfully synthesized and their chemical structures and purity were obtained by 1H NMR.The results showed that the pyrrolidinium-type ionic liquid had the best alkaline stability,the main degradation mode of small molecule cations in alkaline solution was also analyzed by theoretical calculation.Subsequently,the cationic backbone polymer was synthesized by polycondensation reaction,and the corresponding AEMs were prepared.The resulted membranes were tested in water uptake,swelling degree,ionic conductivity and chemical stability,which presented good alkaline stability and ionic conductivity.