| Vanadium flow battery（VFB）is a large-scale electrochemical energy storage technology that has attracted more and more attention due to its fast response speed and flexible battery configuration,etc.The membrane is one of key components,which has a significant effect on battery performance and cost.An ideal membrane should has the advantages of low cost,low vanadium permeation,high proton conductivity,and high stability.Poly（arylene ether）polymers have attracted attention due to their low cost and good stability.Commercial perfluorosulfonic acid membranes have high proton conductivity and stability,but their vanadium permeability is serious and expensive,which limits the large-scale application of VRFBs.Polyarylene ether polymers have attracted attention due to their low cost and good stability.In this paper,combined with the advantages of good microphase separation structure of fluorine-containing materials and low cost of polyarylene ether,fluorine-containing polyarylene ether materials were synthesized,and long functional side chains were introduced to construct a good microphase separation structure and obtain high proton conduction at the same time.A series of side-chain-type ion conducting membranes are prepared.The specific research contents are as follows:（1）Using pentafluorobenzonitrile and sodium 4-hydroxybenzenesulfonate as raw materials,a polymerized monomer containing fluorine group,cyano group and side-chain sulfonic acid group was synthesized.By adjusting the reaction conditions to control the polymerization,a side-chain-type sulfonated fluorinated poly（arylene ether）membrane（SFPAEN）with cyano structure was prepared.The interaction between hydrophobic fluorinated polymer backbone and sulfonated side chain is benift to form an obvious hydrophilic/hydrophobic nanophase separation structure,which results a proton conductivity of88.5 m S cm-1.Meanwhile,the swelling ratio of the membrane is restricted by the strong polar interchain interaction of cyano groups.The VFB assembled with SFPAEN membrane has an EE of 76.7%at 200 m A cm-2,which was higher than that of the Nafion 212membrane（72.8%）.（2）For improving proton conductivity,high-molecular-weight poly（arylene ether）is synthesized by polycondensation reaction using perfluorobiphenyl and resorcinol as raw materials.A series of side chain sulfonated fluorinated poly（arylene ether）membranes（SFPAE）are synthesized by controlling the feeding ratio of sodium4-hydroxybenzenesulfonate.The microscopic interaction between fluorinated main chain and sulfonated side chain,is helpful to form a hydrophilic/hydrophobic nanophase separation structure and promote the transport of protons.The SFPAE membrane with ion exchange capacity of 1.71 mmol g-1,the proton conductivity reaches 108.3 m S cm-1,the area resistance is 0.32Ωcm2,and the vanadium penetration is 1.84×10-8 cm2 s-1.The VFB assembled with SFPAE membrane exhibits an EE of 78.8%at 200 m A cm-2,which was higher than that of the SFPAEN membrane.After 170 cycles at a current density of 80 m A cm-2,the CE and EE remained unchanged.（3）In order to improve the vanadium resistance,2,2-diallyl bisphenol A,bisphenol A and perfluorobiphenyl were polymerized to synthesize the main chain of polyarylether,and then the flexible amine group side was introduced through the reaction of mercapto and olefin.chain,and prepared side-chain aminated fluorine-containing polyarylene ether membrane（AFPAE）.The protonated amine group can transport protons and effectively repel vanadium ions.The AFPAE membrane with IEC of 1.85 mmol g-1 has a proton conductivity of 41.3 m S cm-1,a area resistance of 0.39Ωcm2,and a vanadium penetration of 1.41×10-8 cm2 s-1.Low vanadium penetration ensures high coulombic efficiency（CE）,which improves performance.The AFPAE membrane was applied in VRFB,and the EE of the membrane was 79.8%at a current density of 200 m A cm-2,which was higher than that of the SFPAE membrane.After275 cycles at 80 m A cm-2,the CE and EE dimensions remained stable. |
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