碱性燃料电池用聚烯烃类阴离子交换膜的研究进展
|
摘要
与质子交换膜燃料电池相比,基于阴离子交换膜的碱性燃料电池具有可使用非贵金属催化剂、电极反应速率高等优点,近年来受到广泛的关注.然而,到目前为止,尚未开发出一种高性能的阴离子交换膜以备碱性燃料电池使用.本文从功能单体共聚和高分子接枝改性两方面概述了聚烯烃类阴离子交换膜的制备方法,探讨了膜的化学结构、微观相分离结构与膜性能之间关系,最后总结目前聚烯烃类阴离子交换膜的氢氧燃料电池性能,并对该领域的发展趋势进行了展望.
Anion exchange membrane(AEM) plays a critical role in many environmental and energy devices and processes, such as fuel cell, redox flow battery, and electrodialysis. In particular, when polymeric AEMs are exploited in alkaline fuel cells to replace liquid electrolytes, AEM fuel cells(AEMFC) have attracted worldwide attention because of several inherent advantages over proton exchange membrane fuel cells, e.g. the utilization of less expensive metallic catalysts and enhanced kinetics of oxygen reduction. Among different kinds of AEMs, polyolefin-based AEMs showed great potential for large-scale commercialization because of their excellent chemical stability, easy processability, and low cost. The strategies to synthesize polyolefin anion exchange membrane materials included direct(co)polymerization with functionalized monomers and post-modification of polyolefins. Generally, the ring-opening metathesis polymerization and Ziegler-Natta catalyst mediated polymerization techniques have been successfully employed to synthesized polyolefin AEMs, using the functional monomers including the α-olefin, norbornene, and cyclooctene. Therefore, the chemical structure and composition can be readily tuned to achieve the optimized properties of the resulting AEMs. However, the functional monomers that need complex synthetic procedure have greatly hampered its further commercialization. Radiation-grafting polymerization of vinylbenzyl chloride(VBC) on the polyolefin backbone has been confirmed as another effective method to produce AEMs. Both(partially or fully) fluorinated and hydrocarbon-based polyolefin have been grafted with poly(VBC) under high energy radiation(such as commercial electron-beam accelerators or ~(60)Co γ-ray facilities), and subsequent quaternization allow the synthesis of AEMs with different ionic head-group. In order to produce high-performance AEMs, high irradiation doses were used to get high degree of grafting, which in turn results in a detrimental reduction in the mechanical properties of the resulting AEMs. Therefore, it is necessary to optimise the conditions of grafting reactions. The physicochemical properties of polyolefin-based AEMs are investigated in detail by the measurement of ion exchange capacity, water uptake, swelling ratio, and ionic conductivity, which are well corelated to their chemical structure and microstructure. Moreover, H_2/O_2 AEMFC assembled from polyolefin-based AEMs(especially for radiation-grafted AEMs) are tested under various conditions in terms of types of electrochemical catalysts, cell temperature, gas flow rate, and so on. Thus, this review summarized the recent developments of polyolefin-based AEMs from the synthetic methods to the properties of AEMs and their performance in H_2/O_2 fuel cell. The relationship between chemical structure, properties and morphology of polyolefin-based AEMs will be discussed. At last, we extend the discussion of AEMs to their performance in H_2/O_2 fuel cell, as dramatic improvements of AEM fuel cell performance is accomplished when using highperformance polyolefin-based AEMs.
Anion exchange membrane(AEM) plays a critical role in many environmental and energy devices and processes, such as fuel cell, redox flow battery, and electrodialysis. In particular, when polymeric AEMs are exploited in alkaline fuel cells to replace liquid electrolytes, AEM fuel cells(AEMFC) have attracted worldwide attention because of several inherent advantages over proton exchange membrane fuel cells, e.g. the utilization of less expensive metallic catalysts and enhanced kinetics of oxygen reduction. Among different kinds of AEMs, polyolefin-based AEMs showed great potential for large-scale commercialization because of their excellent chemical stability, easy processability, and low cost. The strategies to synthesize polyolefin anion exchange membrane materials included direct(co)polymerization with functionalized monomers and post-modification of polyolefins. Generally, the ring-opening metathesis polymerization and Ziegler-Natta catalyst mediated polymerization techniques have been successfully employed to synthesized polyolefin AEMs, using the functional monomers including the α-olefin, norbornene, and cyclooctene. Therefore, the chemical structure and composition can be readily tuned to achieve the optimized properties of the resulting AEMs. However, the functional monomers that need complex synthetic procedure have greatly hampered its further commercialization. Radiation-grafting polymerization of vinylbenzyl chloride(VBC) on the polyolefin backbone has been confirmed as another effective method to produce AEMs. Both(partially or fully) fluorinated and hydrocarbon-based polyolefin have been grafted with poly(VBC) under high energy radiation(such as commercial electron-beam accelerators or ~(60)Co γ-ray facilities), and subsequent quaternization allow the synthesis of AEMs with different ionic head-group. In order to produce high-performance AEMs, high irradiation doses were used to get high degree of grafting, which in turn results in a detrimental reduction in the mechanical properties of the resulting AEMs. Therefore, it is necessary to optimise the conditions of grafting reactions. The physicochemical properties of polyolefin-based AEMs are investigated in detail by the measurement of ion exchange capacity, water uptake, swelling ratio, and ionic conductivity, which are well corelated to their chemical structure and microstructure. Moreover, H_2/O_2 AEMFC assembled from polyolefin-based AEMs(especially for radiation-grafted AEMs) are tested under various conditions in terms of types of electrochemical catalysts, cell temperature, gas flow rate, and so on. Thus, this review summarized the recent developments of polyolefin-based AEMs from the synthetic methods to the properties of AEMs and their performance in H_2/O_2 fuel cell. The relationship between chemical structure, properties and morphology of polyolefin-based AEMs will be discussed. At last, we extend the discussion of AEMs to their performance in H_2/O_2 fuel cell, as dramatic improvements of AEM fuel cell performance is accomplished when using highperformance polyolefin-based AEMs.
引文
1 Varcoe J R,Atanassov P,Dekel D R,et al.Anion-exchange membranes in electrochemical energy systems.Energy Environ Sci,2014,7:3135-3191
2 Wang Y J,Qiao J,Baker R,et al.Alkaline polymer electrolyte membranes for fuel cell applications.Chem Soc Rev,2013,42:5768-5787
3 Gottesfeld S,Dekel D R,Page M,et al.Anion exchange membrane fuel cells:Current status and remaining challenges.J Power Sources,2018,375:170-184
4 Cheng J,He G,Zhang F.A mini-review on anion exchange membranes for fuel cell applications:Stability issue and addressing strategies.Int J Hydrogen Energy,2015,40:7348-7360
5 Merle G,Wessling M,Nijmeijer K.Anion exchange membranes for alkaline fuel cells:A review.J Membr Sci,2011,377:1-35
6 Sun Z,Pan J,Guo J,et al.The alkaline stability of anion exchange membrane for fuel cell applications:The effects of alkaline media.Adv Sci,2018,5:1800065
7 Marino M G,Kreuer K D.Alkaline stability of quaternary ammonium cations for alkaline fuel cell membranes and ionic liquids.ChemSusChem,2015,8:513-523
8 Mohanty A D,Bae C.Mechanistic analysis of ammonium cation stability for alkaline exchange membrane fuel cells.J Mater Chem A,2014,2:17314-17320
9 Pan J,Lu S,Li Y,et al.High-performance alkaline polymer electrolyte for fuel cell applications.Adv Func Mater,2010,20:312-319
10 Yan J,Hickner M A.Anion exchange membranes by bromination of benzylmethyl-containing poly(sulfone)s.Macromolecules,2010,43:2349-2356
11 Ran J,Wu L,Ru Y,et al.Anion exchange membranes(AEMs)based on poly(2,6-dimethyl-1,4-phenylene oxide)(PPO)and its derivatives.Polym Chem,2015,6:5809-5826
12 Si J,Lu S,Xu X,et al.A gemini quaternary ammonium poly(ether ether ketone)anion-exchange membrane for alkaline fuel cell:Design,synthesis,and properties.ChemSusChem,2014,7:3389-3395
13 Thomas O D,Soo K J W Y,Peckham T J,et al.A stable hydroxide-conducting polymer.J Am Chem Soc,2012,134:10753-10756
14 Arges C G,Ramani V.Two-dimensional NMR spectroscopy reveals cation-triggered backbone degradation in polysulfone-based anion exchange membranes.Proc Natl Acad Sci USA,2013,110:2490-2495
15 Mohanty A D,Tignor S E,Krause J A,et al.Systematic alkaline stability study of polymer backbones for anion exchange membrane applications.Macromolecules,2016,49:3361-3372
16 Clark T J,Robertson N J,Kostalik IV H A,et al.A ring-opening metathesis polymerization route to alkaline anion exchange membranes:Development of hydroxide-conducting thin films from an ammonium-functionalized monomer.J Am Chem Soc,2009,131:12888-12889
17 Robertson N J,Kostalik IV H A,Clark T J,et al.Tunable high performance cross-linked alkaline anion exchange membranes for fuel cell applications.J Am Chem Soc,2010,132:3400-3404
18 Zha Y,Disabb-Miller M L,Johnson Z D,et al.Metal-cation-based anion exchange membranes.J Am Chem Soc,2012,134:4493-4496
19 Kostalik IV H A,Clark T J,Robertson N J,et al.Solvent processable tetraalkylammonium-functionalized polyethylene for use as an alkaline anion exchange membrane.Macromolecules,2010,43:7147-7150
20 You W,Hugar K M,Coates G W.Synthesis of alkaline anion exchange membranes with chemically stable imidazolium cations:Unexpected cross-linked macrocycles from ring-fused ROMP monomers.Macromolecules,2018,51:3212-3218
21 Noonan K J T,Hugar K M,Kostalik IV H A,et al.Phosphonium-functionalized polyethylene:A new class of base-stable alkaline anion exchange membranes.J Am Chem Soc,2012,134:18161-18164
22 Zhu T,Xu S,Rahman A,et al.Cationic metallo-polyelectrolytes for robust alkaline anion-exchange membrane.Angew Chem Int Ed,2018,57:2388-2392
23 Zhang M,Kim H K,Chalkova E,et al.New polyethylene based anion exchange membranes(PE-AEMs)with high ionic conductivity.Macromolecules,2011,44:5937-5946
24 Zhang M,Liu J,Wang Y,et al.Highly stable anion exchange membranes based on quaternized polypropylene.J Mater Chem A,2015,3:12284-12296
25 Zhang M,Shan C,Liu L,et al.Facilitating anion transport in polyolefin-based anion exchange membranes via bulky side chains.ACSAppl Mater Interfaces,2016,8:23321-23330
26 Meng Z,Su Y,Wu Y,et al.Synthesis and properties of quaternized polyolefins with bulky poly(4-phenyl-1-butene)moieties as anion exchange membranes.J Membr Sci,2017,541:244-252
27 Gu F,Dong H,Li Y,et al.Base stable pyrrolidinium cations for alkaline anion exchange membrane applications.Macromolecules,2014,47:6740-6747
28 Qiu B,Lin B,Si Z,et al.Bis-imidazolium-based anion-exchange membranes for alkaline fuel cells.J Power Sources,2012,217:329-335
29 Danks T N,Slade R C T,Varcoe J R.Alkaline anion-exchange radiation-grafted membranes for possible electrochemical application in fuel cells.J Mater Chem,2003,13:712-721
30 Liu H,Yang S,Wang S,et al.Preparation and characterization of radiation-grafted poly(tetrafluoroethylene-co-perfluoropropyl vinyl ether)membranes for alkaline anion-exchange membrane fuel cells.J Membr Sci,2011,369:227-283
31 Fang J,Yang Y,Lu X,et al.Cross-linked,ETFE-derived and radiation grafted membranes for anion exchange membrane fuel cell applications.Int J Hydrogen Energy,2012,37:594-602
32 Mamlouk M,Horsfall J A,Williams C,et al.Radiation grafted membranes for superior anion exchange polymer membrane fuel cells performance.Int J Hydrog Energy,2012,37:11912-11920
33 Wang L,Brink J J,Liu Y,et al.Non-fluorinated pre-irradiation-grafted(peroxidated)LDPE-based anion-exchange membranes with high performance and stability.Energy Environ Sci,2017,10:2154-2167
34 Wang L,Magliocca E,Cunningham E L,et al.An optimized synthesis of high performance radiation-grafted anion-exchange membranes.Green Chem,2017,19:831-843
35 Park A M,Owczarczyk Z R,Garner L E,et al.Synthesis and characterization of perfluorinated anion exchange membranes.ECS Trans,2017,80:957-966
36 Li N,Guiver M D.Ion transport by nanochannels in ion-containing aromatic copolymers.Macromolecules,2014,47:2175-2198
37 Mohanty A D,Ryu C Y,Kim Y S,et al.Stable elastomeric anion exchange membranes based on quaternary ammonium-tethered polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene triblock copolymers.Macromolecules,2015,48:7085-7095
38 Tanaka M,Fukasawa K,Nishino E,et al.Anion conductive block poly(arylene ether)s:Synthesis,properties,and application in alkaline fuel cells.J Am Chem Soc,2011,133:10646-10654
39 Li N,Leng Y,Hickner M A,et al.Highly stable,anion conductive,comb-shaped copolymers for alkaline fuel cells.J Am Chem Soc,2013,135:10124-10133
40 Wang J,Wang X,Zu D,et al.N3-adamantyl imidazolium cations:Alkaline stability assessment and the corresponding comb-shaped anion exchange membranes.J Membr Sci,2018,545:116-125
41 Weiber E A,Jannasch P.Ion distribution in quaternary-ammonium-functionalized aromatic polymers:Effects on the ionic clustering and conductivity of anion-exchange membranes.ChemSusChem,2014,7:2621-2630
42 Li Q,Liu L,Miao Q,et al.A novel poly(2,6-dimethyl-1,4-phenylene oxide)with trifunctional ammonium moieties for alkaline anion exchange membranes.Chem Commun,2014,50:2791-2793
43 Dang H S,Jannasch P.Exploring different cationic alkyl side chain designs for enhanced alkaline stability and hydroxide ion conductivity of anion-exchange membranes.Macromolecules,2015,48:5742-5751
44 Liu L,Chu X,Liao J,et al.Tuning the properties of poly(2,6-dimethyl-1,4-phenylene oxide)anion exchange membranes and their performance in H2/O2 fuel cells.Energy Environ Sci,2018,11:435-446
45 Li Y,Liu Y,Savage A M,et al.Polyethylene-based block copolymers for anion exchange membranes.Macromolecules,2015,48:6523-6533
46 Ponce-González J,Whelligan D K,Wang L,et al.High performance aliphatic-heterocyclic benzyl-quaternary ammonium radiationgrafted anion-exchange membranes.Energy Environ Sci,2016,9:3724-3735
47 Hu J,Zhang C,Cong J,et al.Plasma-grafted alkaline anion-exchange membranes based on polyvinyl chloride for potential application in direct alcohol fuel cell.J Power Sources,2011,196:4483-4490
48 Deavin O I,Murphy S,Ong A L,et al.Anion-exchange membranes for alkaline polymer electrolyte fuel cells:Comparison of pendent benzyltrimethylammonium-and benzylmethylimidazolium-head-groups.Energy Environ Sci,2012,5:8584-8597
49 Sherazi T A,Zahoor S,Raza R,et al.Guanidine functionalized radiation induced grafted anion-exchange membranes for solid alkaline fuel cells.Int J Hydrog Energy,2015,40:786-796
50 Wang C,Mo B,He Z,et al.Crosslinked norbornene copolymer anion exchange membrane for fuel cells.J Membr Sci,2018,556:118-125
51 Ponce-González J,Ouachan I,Varcoe J R,et al.Radiation-induced grafting of a butyl-spacer styrenic monomer onto ETFE:The synthesis of the most alkali stable radiation-grafted anion-exchange membrane to date.J Mater Chem A,2018,6:823-827
52 Olsson J S,Pham T H,Jannasch P.Poly(arylene piperidinium)hydroxide ion exchange membranes:Synthesis,alkaline stability,and conductivity.Adv Funct Mater,2018,28:1702758-1702767
53 Wright A G,Fan J,Britton B,et al.Hexamethyl-p-terphenyl poly(benzimidazolium):A universal hydroxide-conducting polymer for energy conversion devices.Energy Environ Sci,2016,9:2130-2142
54 Page O M M,Poynton S D,Murphy S,et al.The alkali stability of radiation-grafted anion-exchange membranes containing pendent1-benzyl-2,3-dimethylimidazolium head-groups.RSC Adv,2013,3:579-587
55 Espiritu R,Mamlouk M,Scott K.Study on the effect of the degree of grafting on the performance of polyethylene-based anion exchange membrane for fuel cell application.Int J Hydrog Energy,2016,41:1120-1133
56 Wang L,Brink J J,Varcoe J R.The first anion-exchange membrane fuel cell to exceed 1 W/cm2 at 70°C with a non-Pt-group(O2)cathode.Chem Commun,2017,53:11771-11773
57 Omasta T J,Park A M,LaManna J M,et al.Beyond catalysis and membranes:Visualizing and solving the challenge of electrode water accumulation and flooding in AEMFCs.Energy Environ Sci,2018,11:551-558
2 Wang Y J,Qiao J,Baker R,et al.Alkaline polymer electrolyte membranes for fuel cell applications.Chem Soc Rev,2013,42:5768-5787
3 Gottesfeld S,Dekel D R,Page M,et al.Anion exchange membrane fuel cells:Current status and remaining challenges.J Power Sources,2018,375:170-184
4 Cheng J,He G,Zhang F.A mini-review on anion exchange membranes for fuel cell applications:Stability issue and addressing strategies.Int J Hydrogen Energy,2015,40:7348-7360
5 Merle G,Wessling M,Nijmeijer K.Anion exchange membranes for alkaline fuel cells:A review.J Membr Sci,2011,377:1-35
6 Sun Z,Pan J,Guo J,et al.The alkaline stability of anion exchange membrane for fuel cell applications:The effects of alkaline media.Adv Sci,2018,5:1800065
7 Marino M G,Kreuer K D.Alkaline stability of quaternary ammonium cations for alkaline fuel cell membranes and ionic liquids.ChemSusChem,2015,8:513-523
8 Mohanty A D,Bae C.Mechanistic analysis of ammonium cation stability for alkaline exchange membrane fuel cells.J Mater Chem A,2014,2:17314-17320
9 Pan J,Lu S,Li Y,et al.High-performance alkaline polymer electrolyte for fuel cell applications.Adv Func Mater,2010,20:312-319
10 Yan J,Hickner M A.Anion exchange membranes by bromination of benzylmethyl-containing poly(sulfone)s.Macromolecules,2010,43:2349-2356
11 Ran J,Wu L,Ru Y,et al.Anion exchange membranes(AEMs)based on poly(2,6-dimethyl-1,4-phenylene oxide)(PPO)and its derivatives.Polym Chem,2015,6:5809-5826
12 Si J,Lu S,Xu X,et al.A gemini quaternary ammonium poly(ether ether ketone)anion-exchange membrane for alkaline fuel cell:Design,synthesis,and properties.ChemSusChem,2014,7:3389-3395
13 Thomas O D,Soo K J W Y,Peckham T J,et al.A stable hydroxide-conducting polymer.J Am Chem Soc,2012,134:10753-10756
14 Arges C G,Ramani V.Two-dimensional NMR spectroscopy reveals cation-triggered backbone degradation in polysulfone-based anion exchange membranes.Proc Natl Acad Sci USA,2013,110:2490-2495
15 Mohanty A D,Tignor S E,Krause J A,et al.Systematic alkaline stability study of polymer backbones for anion exchange membrane applications.Macromolecules,2016,49:3361-3372
16 Clark T J,Robertson N J,Kostalik IV H A,et al.A ring-opening metathesis polymerization route to alkaline anion exchange membranes:Development of hydroxide-conducting thin films from an ammonium-functionalized monomer.J Am Chem Soc,2009,131:12888-12889
17 Robertson N J,Kostalik IV H A,Clark T J,et al.Tunable high performance cross-linked alkaline anion exchange membranes for fuel cell applications.J Am Chem Soc,2010,132:3400-3404
18 Zha Y,Disabb-Miller M L,Johnson Z D,et al.Metal-cation-based anion exchange membranes.J Am Chem Soc,2012,134:4493-4496
19 Kostalik IV H A,Clark T J,Robertson N J,et al.Solvent processable tetraalkylammonium-functionalized polyethylene for use as an alkaline anion exchange membrane.Macromolecules,2010,43:7147-7150
20 You W,Hugar K M,Coates G W.Synthesis of alkaline anion exchange membranes with chemically stable imidazolium cations:Unexpected cross-linked macrocycles from ring-fused ROMP monomers.Macromolecules,2018,51:3212-3218
21 Noonan K J T,Hugar K M,Kostalik IV H A,et al.Phosphonium-functionalized polyethylene:A new class of base-stable alkaline anion exchange membranes.J Am Chem Soc,2012,134:18161-18164
22 Zhu T,Xu S,Rahman A,et al.Cationic metallo-polyelectrolytes for robust alkaline anion-exchange membrane.Angew Chem Int Ed,2018,57:2388-2392
23 Zhang M,Kim H K,Chalkova E,et al.New polyethylene based anion exchange membranes(PE-AEMs)with high ionic conductivity.Macromolecules,2011,44:5937-5946
24 Zhang M,Liu J,Wang Y,et al.Highly stable anion exchange membranes based on quaternized polypropylene.J Mater Chem A,2015,3:12284-12296
25 Zhang M,Shan C,Liu L,et al.Facilitating anion transport in polyolefin-based anion exchange membranes via bulky side chains.ACSAppl Mater Interfaces,2016,8:23321-23330
26 Meng Z,Su Y,Wu Y,et al.Synthesis and properties of quaternized polyolefins with bulky poly(4-phenyl-1-butene)moieties as anion exchange membranes.J Membr Sci,2017,541:244-252
27 Gu F,Dong H,Li Y,et al.Base stable pyrrolidinium cations for alkaline anion exchange membrane applications.Macromolecules,2014,47:6740-6747
28 Qiu B,Lin B,Si Z,et al.Bis-imidazolium-based anion-exchange membranes for alkaline fuel cells.J Power Sources,2012,217:329-335
29 Danks T N,Slade R C T,Varcoe J R.Alkaline anion-exchange radiation-grafted membranes for possible electrochemical application in fuel cells.J Mater Chem,2003,13:712-721
30 Liu H,Yang S,Wang S,et al.Preparation and characterization of radiation-grafted poly(tetrafluoroethylene-co-perfluoropropyl vinyl ether)membranes for alkaline anion-exchange membrane fuel cells.J Membr Sci,2011,369:227-283
31 Fang J,Yang Y,Lu X,et al.Cross-linked,ETFE-derived and radiation grafted membranes for anion exchange membrane fuel cell applications.Int J Hydrogen Energy,2012,37:594-602
32 Mamlouk M,Horsfall J A,Williams C,et al.Radiation grafted membranes for superior anion exchange polymer membrane fuel cells performance.Int J Hydrog Energy,2012,37:11912-11920
33 Wang L,Brink J J,Liu Y,et al.Non-fluorinated pre-irradiation-grafted(peroxidated)LDPE-based anion-exchange membranes with high performance and stability.Energy Environ Sci,2017,10:2154-2167
34 Wang L,Magliocca E,Cunningham E L,et al.An optimized synthesis of high performance radiation-grafted anion-exchange membranes.Green Chem,2017,19:831-843
35 Park A M,Owczarczyk Z R,Garner L E,et al.Synthesis and characterization of perfluorinated anion exchange membranes.ECS Trans,2017,80:957-966
36 Li N,Guiver M D.Ion transport by nanochannels in ion-containing aromatic copolymers.Macromolecules,2014,47:2175-2198
37 Mohanty A D,Ryu C Y,Kim Y S,et al.Stable elastomeric anion exchange membranes based on quaternary ammonium-tethered polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene triblock copolymers.Macromolecules,2015,48:7085-7095
38 Tanaka M,Fukasawa K,Nishino E,et al.Anion conductive block poly(arylene ether)s:Synthesis,properties,and application in alkaline fuel cells.J Am Chem Soc,2011,133:10646-10654
39 Li N,Leng Y,Hickner M A,et al.Highly stable,anion conductive,comb-shaped copolymers for alkaline fuel cells.J Am Chem Soc,2013,135:10124-10133
40 Wang J,Wang X,Zu D,et al.N3-adamantyl imidazolium cations:Alkaline stability assessment and the corresponding comb-shaped anion exchange membranes.J Membr Sci,2018,545:116-125
41 Weiber E A,Jannasch P.Ion distribution in quaternary-ammonium-functionalized aromatic polymers:Effects on the ionic clustering and conductivity of anion-exchange membranes.ChemSusChem,2014,7:2621-2630
42 Li Q,Liu L,Miao Q,et al.A novel poly(2,6-dimethyl-1,4-phenylene oxide)with trifunctional ammonium moieties for alkaline anion exchange membranes.Chem Commun,2014,50:2791-2793
43 Dang H S,Jannasch P.Exploring different cationic alkyl side chain designs for enhanced alkaline stability and hydroxide ion conductivity of anion-exchange membranes.Macromolecules,2015,48:5742-5751
44 Liu L,Chu X,Liao J,et al.Tuning the properties of poly(2,6-dimethyl-1,4-phenylene oxide)anion exchange membranes and their performance in H2/O2 fuel cells.Energy Environ Sci,2018,11:435-446
45 Li Y,Liu Y,Savage A M,et al.Polyethylene-based block copolymers for anion exchange membranes.Macromolecules,2015,48:6523-6533
46 Ponce-González J,Whelligan D K,Wang L,et al.High performance aliphatic-heterocyclic benzyl-quaternary ammonium radiationgrafted anion-exchange membranes.Energy Environ Sci,2016,9:3724-3735
47 Hu J,Zhang C,Cong J,et al.Plasma-grafted alkaline anion-exchange membranes based on polyvinyl chloride for potential application in direct alcohol fuel cell.J Power Sources,2011,196:4483-4490
48 Deavin O I,Murphy S,Ong A L,et al.Anion-exchange membranes for alkaline polymer electrolyte fuel cells:Comparison of pendent benzyltrimethylammonium-and benzylmethylimidazolium-head-groups.Energy Environ Sci,2012,5:8584-8597
49 Sherazi T A,Zahoor S,Raza R,et al.Guanidine functionalized radiation induced grafted anion-exchange membranes for solid alkaline fuel cells.Int J Hydrog Energy,2015,40:786-796
50 Wang C,Mo B,He Z,et al.Crosslinked norbornene copolymer anion exchange membrane for fuel cells.J Membr Sci,2018,556:118-125
51 Ponce-González J,Ouachan I,Varcoe J R,et al.Radiation-induced grafting of a butyl-spacer styrenic monomer onto ETFE:The synthesis of the most alkali stable radiation-grafted anion-exchange membrane to date.J Mater Chem A,2018,6:823-827
52 Olsson J S,Pham T H,Jannasch P.Poly(arylene piperidinium)hydroxide ion exchange membranes:Synthesis,alkaline stability,and conductivity.Adv Funct Mater,2018,28:1702758-1702767
53 Wright A G,Fan J,Britton B,et al.Hexamethyl-p-terphenyl poly(benzimidazolium):A universal hydroxide-conducting polymer for energy conversion devices.Energy Environ Sci,2016,9:2130-2142
54 Page O M M,Poynton S D,Murphy S,et al.The alkali stability of radiation-grafted anion-exchange membranes containing pendent1-benzyl-2,3-dimethylimidazolium head-groups.RSC Adv,2013,3:579-587
55 Espiritu R,Mamlouk M,Scott K.Study on the effect of the degree of grafting on the performance of polyethylene-based anion exchange membrane for fuel cell application.Int J Hydrog Energy,2016,41:1120-1133
56 Wang L,Brink J J,Varcoe J R.The first anion-exchange membrane fuel cell to exceed 1 W/cm2 at 70°C with a non-Pt-group(O2)cathode.Chem Commun,2017,53:11771-11773
57 Omasta T J,Park A M,LaManna J M,et al.Beyond catalysis and membranes:Visualizing and solving the challenge of electrode water accumulation and flooding in AEMFCs.Energy Environ Sci,2018,11:551-558