Preparation And Study Of Imidazole Grafted Polyetheretherketone Anion Exchange Membranes For Fuel Cells

In recent years,The development of Alkaline Fuel Cell?AFC?has received widespread attention.On the one hand,non-noble metals can be used as catalysts in AFC,such as silver and nickel which reduced the cost of fuel cell devices.On the other hand,Since the OH^-transfer direction is opposite to the direction of penetration of the fuel,the fuel permeability is reduced.Anion exchange membrane?AEM?has been widely studied as an important part of AFC.AEM is mainly composed of two parts:functional group and polymer main chain.All functional groups in AEM are cationic groups,such as quaternary ammonium,imidazolium,guanidinium and phosphonium.Quaternary ammonium group and imidazolium group are the most commonly used cationic group.The researchers found that imidazole-type anion exchange membrane has better performance.However,due to its strong hydrophilicity,the membrane will be excessively expanded when the imidazole group content is too high in the membrane,thereby reducing the dimensional stability of the membrane.We did a series of studies in order to solve this problem.First of all,the polymer backbone is polyether ether ketone?PEEK?.And introduced an imidazole group with a double bond:1-vinylimidazole.Two types of AEM were prepared:crosslinked membranes?CIM-PEEK?and non-crosslinked membranes?NCIM-PEEK?.And the performance of the two membranes was tested and analyzed.The analysis results show that the CIM-PEEK membranes have a very low swelling rate and excellent alkali resistance.The NCIM-PEEK membranes have higher ion conductivity and water absorption,and membranes have good mechanical properties and thermal stability.In this study,a benzylmethyl-containing PEEK copolymer is synthesized through condensation polymerization of 4,4'-difluorobenzopheno and methylhydroquinone.The brominated poly?ether ether ketone??BPEEK?was chosen to react directly with the functional reagent,1-methylimidazole and 1-vinylimidazole,and obtained polyether?ether ether ketone?anion exchange membranes of containing different imidazolium groups.With increasing 1-vinylimidazole content,the swelling rate dropped from 36.29%to 8.52%at80^oC.With increasing 1-methylimidazole content,the ion conductivity increases from5.15×10^-2 Scm^-1 to 7.12×10^-2 Scm^-1,and the water uptake increases from 12.57%to17.19%at 80^oC.The initial conductivity remained 80.15%in 2M of NaOH solution at60^oC for 500h.Overall,appropriate cross-linking helps to improve the overall performance of membranes.