Design And Preparation Of Grafted Imidazolium Anion Exchange Membrane

Polymer Electrolyte Membranes Fuel Cells(PEMFCs),as newly-style energy conversion devices,have attracted a great deal of research interest due to their advantages of pollute-free,higher-efficiency in recent years.Compared to Proton Exchange Membrane Fuel Fells(PEMFCs),Anion Exchange Membrane Fuel Fells(AEMFCs)use non-precious metal catalysts,such as silver,nickel,and cobalt,and have a faster reaction kinetics process which have both low cost and high efficiency,thus they provide unlimited potential for commercial development.However,compared to Proton Exchange Membranes(PEMs),Anion Exchange Membranes(AEMs)suffer lower conductivity and poor long-term chemical stability,which hinder the commercialization of AEMFCsMany different strategies are explored to improve the performance of ionic membranes,such as changing the structure and position of the functional groups or regulating the degree of cross-linking of the polymers.However,these strategies have very poor effect.Inspired by the structure of Nafion,the structural design of polymers is used to control the microscopic morphology of membranes,which has been demonstrated to obtain high-performance ion exchange membranes.To fulfill the purpose of simultaneously improving the hydroxide conductivity and alkali stability of the anion membrane,we make a special design of polymer structure.The detailed contents are summarized follows:(1)Membranes with different graft densities and side-chain lengths were obtained by Atom Transfer Radical Polymerization(ATRP)with poly(2,6-dimethyl-1,4-phenylene oxide)(PPO)as the main chain;This regulation of the side chain and graft density can be matched well with the performance of the membranes and improves the performance greatly of the membrane.The membrane(LDGPM)with lower graft density and longer side chain has a conductivity of more than 50 mS/cm at room temperature,which is much higher than most of the membranes reported so far,and after immersed for 600 hours in 2M NaOH solution(60?),IEC degradation is only 21%.(2)Functionalized p-chloromethyl styrene(VBC),as an ionic precursor,can help to overcome the drawbacks of post-functionalization process on the membrane performance.Meanwhile,we selected the C2-methyl substituted imidazolium as functional group,avoiding the attack of the hydroxide ion on the C2 position and improving the alkali resistance of the ionic group.(3)The study of the relationship between polymer structure and membrane performance,provides guidance for the design of high-performance ion membrane structures.