Chinese Science Bulletin, Volume 64 , Issue 2 : 180-186(2019) https://doi.org/10.1360/N972018-00679

The ordered side chain imidazole functionalized cross-linked anion exchange membrane

More info
  • ReceivedJul 9, 2018
  • AcceptedSep 17, 2018
  • PublishedOct 31, 2018


In recent years, the development of alkaline anion exchange membrane fuel cells (AEMFCs) has received widespread attention. On the one hand, non-noble metals can be used as catalysts in alkaline anion exchange membrane fuel cells (AEMFCs), such as silver and nickel which reduced the cost of fuel cell devices. On the other hand, the hydroxide ions move in the opposite direction with the fuel, which reduce fuel permeability and the cost on other aspects. Therefore, the development prospect of alkaline fuel cells is good, while anion exchange membrane, as the core component of alkaline fuel cells, has problems such as the insufficient ion conductivity and alkaline stability, which hinder the successful realization of AEMFCs technology. Until now, many cationic groups have been widely investigated, such as quaternary ammonium, imidazolium, guanidinium and phosphonium. Quaternary ammonium group and imidazolium group are the most commonly used cationic group. The experimental results suggest that imidazole-type anion exchange membrane have better performance. Due to the existence of the conjugated π bond in the unique N-heterocyclic structure, imidazolium grafted membranes exhibit not only high ionic conductivity, but also excellent chemical and thermal stability. The formation of cross-linked network structure is advantageous in suppressing the swelling of the membrane, thereby improving the dimensional stability of the membrane. Meantime, we introduce 1-vinylimidazole to improve the performance of the 1-methylimidazole grafted membrane. This monomer contains not only imidazolium cation groups, but also double bonds can be cross-linked. The imidazole group can transfer OH- ions. The dense network structure formed by double bonds cross-linking makes membranes have good mechanical properties and dimensional stability, and conducive to defense strong nucleophile OH- attack.

First, a benzylmethyl-containing poly ether (ether ether ketone) (PEEK) copolymer was synthesized through condensation polymerization of 4,4′-difluorobenzopheno and methylhydroquinone. Then, dissolved the PEEK by 1,1,2,2-tetra- chloroethane, the yellow precipitate bromination of polyether ether ketone (BPEEK) was synthesized by adding NBS and BPO into the solution and reacted at 80°C for 5 h under the nitrogen atmosphere. The BPEEK was chosen to react directly with the functional reagent, 1-methyl imidazole and 1-vinylimidazole and obtained poly (ether ether ketone) crosslinked anion exchange membranes. The structure was characterized by 1H NMR spectroscopy. The morphology and microstructure of the resulting samples were characterized using transmission electron microscopy (TEM). The ion conductivity of the Im-PEEK-x membrane was measured by four-probe alternating current (AC) impedance technique. The thermal stability was tested by thermogravimetric analysis (TGA). The alkaline solution stability of the Im-PEEK-x membrane was evaluated by measuring the changes in IEC values after immersed in 1 mol/L NaOH for a certain time. Water uptake, swelling ratio and mechanical properties of the membranes were also measured.

The results indicated that the Im-PEEK-x membrane had been synthesized. After grafting of 1-vinylimidazole, for the membrane of Im-PEEK-0.7, the maximum stress is 60.03 MPa, and the swelling rate is 18.2% at 80°C. After soaking in 1 mol L–1 NaOH solution for 200 h at 80°C, the IEC value was about 81.5% of the initial, which exhibited excellent alkaline stability.

Funded by




[1] McLean G. An assessment of alkaline fuel cell technology. Int J Hydrogen Energy, 2002, 27: 507-526 CrossRef Google Scholar

[2] Varcoe J R, Slade R C T, Wright G L, et al. Steady-State dc and Impedance Investigations of H2 /O2 Alkaline Membrane Fuel Cells with Commercial Pt/C, Ag/C, and Au/C Cathodes. J Phys Chem B, 2006, 110: 21041-21049 CrossRef Google Scholar

[3] Tang D P, Pan J, Lu S F, et al. Alkaline polymer electrolyte fuel cells: Principle, challenges, and recent progress. Sci China Chem, 2010, 53: 357-364 CrossRef Google Scholar

[4] Spendelow J S, Goodpaster J D, Kenis P J A, et al. Mechanism of CO Oxidation on Pt(111) in alkaline media. J Phys Chem B, 2006, 110: 9545-9555 CrossRef Google Scholar

[5] Dang H S, Jannasch P. Anion-exchange membranes with polycationic alkyl side chains attached via spacer units. J Mater Chem A, 2016, 4: 17138-17153 CrossRef Google Scholar

[6] He S, Liu L, Wang X, et al. Azide-assisted self-crosslinking of highly ion conductive anion exchange membranes. J Membrane Sci, 2016, 509: 48-56 CrossRef Google Scholar

[7] Gong X, Yan X, Li T, et al. Design of pendent imidazolium side chain with flexible ether-containing spacer for alkaline anion exchange membrane. J Membrane Sci, 2017, 523: 216-224 CrossRef Google Scholar

[8] Zhuo Y Z, Lai A L, Zhang Q G, et al. Enhancement of hydroxide conductivity by grafting flexible pendant imidazolium groups into poly(arylene ether sulfone) as anion exchange membranes. J Mater Chem A, 2015, 3: 18105-18114 CrossRef Google Scholar

[9] Lee K H, Cho D H, Kim Y M, et al. Highly conductive and durable poly(arylene ether sulfone) anion exchange membrane with end-group cross-linking. Energy Environ Sci, 2017, 10: 275-285 CrossRef Google Scholar

[10] Sajjad S D, Liu D, Wei Z, et al. Guanidinium based blend anion exchange membranes for direct methanol alkaline fuel cells (DMAFCs). J Power Sources, 2015, 300: 95-103 CrossRef ADS Google Scholar

[11] Lin B, Qiu L, Qiu B, et al. a soluble and conductive polyfluorene ionomer with pendant imidazolium groups for alkaline fuel cell applications. Macromolecules, 2011, 44: 9642-9649 CrossRef ADS Google Scholar

[12] Zhao J, Yan F, Chen Z, et al. Microemulsion polymerization of cationic pyrroles bearing an imidazolum-ionic liquid moiety. J Polym Sci A Polym Chem, 2010, 47: 746-753 CrossRef ADS Google Scholar

[13] Liu L, Ahlfield J, Tricker A, et al. Anion conducting multiblock copolymer membranes with partial fluorination and long head-group tethers. J Mater Chem A, 2016, 4: 16233-16244 CrossRef Google Scholar

[14] Agel E, Bouet J, Fauvarque J F. Characterization and use of anionic membranes for alkaline fuel cells. J Power Sources, 2001, 101: 267-274 CrossRef ADS Google Scholar

[15] Li C, Wang S, Wang W, et al. A cross-linked fluorinated poly (aryl ether oxadiazole) s using a thermal cross-linking for anion exchange membranes. Int J Hydrogen Energy, 2013, 38: 11038-11044 CrossRef Google Scholar

[16] Lai A N, Wang L S, Lin C X, et al. Phenolphthalein-based poly(arylene ether sulfone nitrile)s multiblock copolymers as anion exchange membranes for alkaline fuel cells. ACS Appl Mater Interfaces, 2015, 7: 8284-8292 CrossRef Google Scholar

[17] Han K W, Ko K H, Abu-Hakmeh K, et al. Molecular dynamics simulation study of a polysulfone-based anion exchange membrane in comparison with the proton exchange membrane. J Phys Chem C, 2014, 118: 12577-12587 CrossRef Google Scholar

[18] Zhu L, Pan J, Wang Y, et al. Multication side chain anion exchange membranes. Macromolecules, 2016, 49: 815-824 CrossRef ADS Google Scholar

[19] Fang J, Lyu M, Wang X, et al. Synthesis and performance of novel anion exchange membranes based on imidazolium ionic liquids for alkaline fuel cell applications. J Power Sources, 2015, 284: 517-523 CrossRef ADS Google Scholar

[20] Ngo H L, LeCompte K, Hargens L, et al. Thermal properties of imidazolium ionic liquids. Thermochim Acta, 2000, 357: 97–102. Google Scholar

[21] Merle G, Wessling M, Nijmeijer K. Anion exchange membranes for alkaline fuel cells: A review. J Membrane Sci, 2011, 377: 1-35 CrossRef Google Scholar

[22] Meek K M, Elabd Y A. Alkaline chemical stability of polymerized ionic liquids with various cations. Macromolecules, 2015, 48: 7071-7084 CrossRef ADS Google Scholar

[23] Meek K M, Nykaza J R, Elabd Y A. Alkaline chemical stability and ion transport in polymerized ionic liquids with various backbones and cations. Macromolecules, 2016, 49: 3382-3394 CrossRef ADS Google Scholar

[24] Guo D, Zhuo Y Z, Lai A N, et al. Interpenetrating anion exchange membranes using poly(1-vinylimidazole) as bifunctional crosslinker for fuel cells. J Membrane Sci, 2016, 518: 295-304 CrossRef Google Scholar

Copyright 2020  CHINA SCIENCE PUBLISHING & MEDIA LTD.  中国科技出版传媒股份有限公司  版权所有

京ICP备14028887号-23       京公网安备11010102003388号