Aryl-ether bonds are facile to attack by oxidizing radicals,thus stimulating the exploitation of ether-free polymers as proton exchange membranes(PEMs)for the long-lasting operation of fuel cells.In this study,a novel...Aryl-ether bonds are facile to attack by oxidizing radicals,thus stimulating the exploitation of ether-free polymers as proton exchange membranes(PEMs)for the long-lasting operation of fuel cells.In this study,a novel class of PEMs derived from all-carbon fluorinated backbone polymers containing sulfide-linked alkyl sulfonic acid side chains have been developed through a straightforward and effective synthetic procedure.The sulfide-linked alkyl sulfonate groups were tethered to the poly(triphenylene pentafluorophenyl)backbone through a quantified and site-specific para-fluoro-thiol click reaction.Owing to the existence of obvious phase separation morphology between hydrophobic main chain and hydrophilic sulfonate groups in the side chains,resulting PEMs demonstrated favorable proton conductivity of 142.5m S/cm at 80℃,while maintaining excellent dimensional stability with an in-plane swelling ratio of<17%as well as a through-plane swelling ratio of<25%.They also exhibit elevated thermal decomposition temperatures(Td5%exceeding 300℃)alongside high tensile strength(>50 MPa).Furthermore,the ether-free full-carbon fluorinated main chain and the-S-group in the side chain,which serves as an effective freeradical scavenger,providing good chemical stability during Fenton’s test.The PEMs achieved a maximum power density of 407 m W/cm^(2)in a single H^(2)/air fuel cell,and an open-circuit voltage decline rate of 0.275 m V/h in a durability test at 30%RH and 80℃.Concurrently,the hydrogen crossover current density is only 1/3 of that of Nafion 212.These findings reveal that the resulted PEMs display considerable antioxidative properties along with commendable performance,with prospective applications in proton exchange membrane fuel cells.展开更多
The thiol-imidazole functionalized(p-triphenyl-pentafluorobenzaldehyde)polymer(IMPTP)was prepared and quaternized with different side chains to obtain imidazolium-modified Me-IMPTP,He-IMPTP and BIM-IMPTP membranes for...The thiol-imidazole functionalized(p-triphenyl-pentafluorobenzaldehyde)polymer(IMPTP)was prepared and quaternized with different side chains to obtain imidazolium-modified Me-IMPTP,He-IMPTP and BIM-IMPTP membranes for application in high-temperature proton exchange membrane fuel cells(HT-PEMFCs).The presence of the thioether group in the polymers enabled radical scavenging for antioxidant properties,while imidazolium cations interacted strongly with H_(2)PO_(4) to prevent phosphoric acid(PA)leaching.The prepared BIM-IMPTP membrane incorporating bisimidazolium cation string with a long alkyl spacer demonstrated the highest mass retention of 82.93%after being immersed in Fenton's reagent for 24 h.Additionally,the PA-doped BIM-IMPTP membranes exhibited excellent PA retention under high-humidity conditions(80℃/100%RH).The single cell equipped with the BIM-IMPTP/320%PA membrane achieved a maximum power density(PDmax)of 945 mW cm^(-2)at 160℃.Among the four membranes with a similar acid doping content(ADC),the BIM-IMPTP/163%PA membrane with bis-cation pairs in the side chains exhibited a well-developed microphase-separated structure and high proton conductivity(119.0 mS cm^(-1)at 180℃).The single cell assembled with BIM-IMPTP/163%PA membrane maintained a PDmax of 613 mW cm^(-2)at 160℃ and demonstrated long-term operational stability under both 150/400 mA cm^(-2)and 80℃/200 mA cm^(-2)conditions.These results indicate that the introduction of thioether and bis-cation pairs in the structural design of polymers contributes significantly to the long-term stability of HT-PEMs.展开更多
The most practical high-temperature proton exchange membranes(PEMs) are phosphoric acid(PA)-doped polymer electrolytes. However, due to the plasticizing effect of PA, it is a challenge to address the trade-off between...The most practical high-temperature proton exchange membranes(PEMs) are phosphoric acid(PA)-doped polymer electrolytes. However, due to the plasticizing effect of PA, it is a challenge to address the trade-off between the proton conductivity and the mechanical performance of these materials. Here,we report an effective strategy to fabricate robust high-temperature PEMs based on the in situ electrostatic crosslinking of polyoxometalates and polymers. A comb copolymer poly(ether-ether-ketone)-grafted-poly(2-ethyl-2-oxazoline)(PGE) with transformable side chains was synthesized and complexed with H_(3)PW_(12)O_(40)(PW) by electrostatic self-assembly, forming PGE/PW nanocomposite membranes with bicontinuous nanostructures. After a subsequent PA-treatment of these membranes, high-temperature PEMs of PGE/PW/PA ternary nanocomposites were obtained, in which the in situ electrostatic crosslinking effect between PW and PGE side chains was generated in the hydrophilic domains of the bicontinuous structures. The microphase separation structure and the electrostatic crosslinking feature endow the PGE/PW/PA membranes with excellent anhydrous proton conductive ability while retaining high mechanical performance. The membranes show a high proton conductivity of 42.5 m S/cm at 150 ℃ and a high tensile strength of 13 MPa. Our strategy can pave a new route based on electrostatic control to design nanostructured polymer electrolytes.展开更多
The key challenge for the use of polymer electrolytes is to realize a high ionic conductivity without scarifying their mechanical performance.Herein,we report a facile strategy to prepare a nanostructured polymer elec...The key challenge for the use of polymer electrolytes is to realize a high ionic conductivity without scarifying their mechanical performance.Herein,we report a facile strategy to prepare a nanostructured polymer electrolyte with both high proton conductivity and high modulus,based on the electrostatic self-assembly of polyoxometalate cluster H_(3)PW_(12)O_(40)(PW)and comb copolymer poly(ether-etherketone)-grafted-poly(vinyl pyrrolidone)(PEEK-gPVP).The incorporation of protonic acid PW can enable the PEEK-g-PVP to be highly proton conductive and create flexible composite electrolyte membranes.Moreover,nanoscale phase separation between PEEK domains and PVP/PW domains spontaneously occurs in these membranes,forming a bicontinuous structure with three-dimensional(3D)-connected PW networks.Due to the dual role of PW networks as both proton transport pathways and mechanical enhancers,these membranes exhibit proton conductivities higher than 30 mS cm^(−1) and modulus over 4 GPa.Notably,the direct methanol fuel cells equipped with these membranes show good cell performance.Given the wide tunability of comb copolymers and polyoxometalates,this system can be extended to develop a variety of functional electrolyte materials,for example,the lithium-ion conductive electrolytes by using polyoxometalatebased lithium salts,which provides a promising platform to explore versatile electrolyte materials for energy and electronic applications.展开更多
基金supported by the Development of Scientific and Technological Project of Jilin Province(No.20230201139GX)。
文摘Aryl-ether bonds are facile to attack by oxidizing radicals,thus stimulating the exploitation of ether-free polymers as proton exchange membranes(PEMs)for the long-lasting operation of fuel cells.In this study,a novel class of PEMs derived from all-carbon fluorinated backbone polymers containing sulfide-linked alkyl sulfonic acid side chains have been developed through a straightforward and effective synthetic procedure.The sulfide-linked alkyl sulfonate groups were tethered to the poly(triphenylene pentafluorophenyl)backbone through a quantified and site-specific para-fluoro-thiol click reaction.Owing to the existence of obvious phase separation morphology between hydrophobic main chain and hydrophilic sulfonate groups in the side chains,resulting PEMs demonstrated favorable proton conductivity of 142.5m S/cm at 80℃,while maintaining excellent dimensional stability with an in-plane swelling ratio of<17%as well as a through-plane swelling ratio of<25%.They also exhibit elevated thermal decomposition temperatures(Td5%exceeding 300℃)alongside high tensile strength(>50 MPa).Furthermore,the ether-free full-carbon fluorinated main chain and the-S-group in the side chain,which serves as an effective freeradical scavenger,providing good chemical stability during Fenton’s test.The PEMs achieved a maximum power density of 407 m W/cm^(2)in a single H^(2)/air fuel cell,and an open-circuit voltage decline rate of 0.275 m V/h in a durability test at 30%RH and 80℃.Concurrently,the hydrogen crossover current density is only 1/3 of that of Nafion 212.These findings reveal that the resulted PEMs display considerable antioxidative properties along with commendable performance,with prospective applications in proton exchange membrane fuel cells.
基金supported by the National Natural Science Foundation of China(No.22179047)the Development of Scientific and Technological Project of Jilin Province(20230201139GX).
文摘The thiol-imidazole functionalized(p-triphenyl-pentafluorobenzaldehyde)polymer(IMPTP)was prepared and quaternized with different side chains to obtain imidazolium-modified Me-IMPTP,He-IMPTP and BIM-IMPTP membranes for application in high-temperature proton exchange membrane fuel cells(HT-PEMFCs).The presence of the thioether group in the polymers enabled radical scavenging for antioxidant properties,while imidazolium cations interacted strongly with H_(2)PO_(4) to prevent phosphoric acid(PA)leaching.The prepared BIM-IMPTP membrane incorporating bisimidazolium cation string with a long alkyl spacer demonstrated the highest mass retention of 82.93%after being immersed in Fenton's reagent for 24 h.Additionally,the PA-doped BIM-IMPTP membranes exhibited excellent PA retention under high-humidity conditions(80℃/100%RH).The single cell equipped with the BIM-IMPTP/320%PA membrane achieved a maximum power density(PDmax)of 945 mW cm^(-2)at 160℃.Among the four membranes with a similar acid doping content(ADC),the BIM-IMPTP/163%PA membrane with bis-cation pairs in the side chains exhibited a well-developed microphase-separated structure and high proton conductivity(119.0 mS cm^(-1)at 180℃).The single cell assembled with BIM-IMPTP/163%PA membrane maintained a PDmax of 613 mW cm^(-2)at 160℃ and demonstrated long-term operational stability under both 150/400 mA cm^(-2)and 80℃/200 mA cm^(-2)conditions.These results indicate that the introduction of thioether and bis-cation pairs in the structural design of polymers contributes significantly to the long-term stability of HT-PEMs.
基金financial support from the National Natural Science Foundation of China (No. 22075097)the Program for JLU Science and Technology Innovative Research Team (No. 2017TD-10)the Open Research Fund of State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences (No. 2020–09)。
文摘The most practical high-temperature proton exchange membranes(PEMs) are phosphoric acid(PA)-doped polymer electrolytes. However, due to the plasticizing effect of PA, it is a challenge to address the trade-off between the proton conductivity and the mechanical performance of these materials. Here,we report an effective strategy to fabricate robust high-temperature PEMs based on the in situ electrostatic crosslinking of polyoxometalates and polymers. A comb copolymer poly(ether-ether-ketone)-grafted-poly(2-ethyl-2-oxazoline)(PGE) with transformable side chains was synthesized and complexed with H_(3)PW_(12)O_(40)(PW) by electrostatic self-assembly, forming PGE/PW nanocomposite membranes with bicontinuous nanostructures. After a subsequent PA-treatment of these membranes, high-temperature PEMs of PGE/PW/PA ternary nanocomposites were obtained, in which the in situ electrostatic crosslinking effect between PW and PGE side chains was generated in the hydrophilic domains of the bicontinuous structures. The microphase separation structure and the electrostatic crosslinking feature endow the PGE/PW/PA membranes with excellent anhydrous proton conductive ability while retaining high mechanical performance. The membranes show a high proton conductivity of 42.5 m S/cm at 150 ℃ and a high tensile strength of 13 MPa. Our strategy can pave a new route based on electrostatic control to design nanostructured polymer electrolytes.
基金The authors acknowledge financial support from the National Natural Science Foundation of China(no.22075097)the Program for JLU Science and Technology Innovative Research Team(no.2017TD-10)the Open Research Fund of State Key Laboratory of Polymer Physics and Chemistry,Changchun Institute of Applied Chemistry,Chinese Academy of Sciences(2020-09).
文摘The key challenge for the use of polymer electrolytes is to realize a high ionic conductivity without scarifying their mechanical performance.Herein,we report a facile strategy to prepare a nanostructured polymer electrolyte with both high proton conductivity and high modulus,based on the electrostatic self-assembly of polyoxometalate cluster H_(3)PW_(12)O_(40)(PW)and comb copolymer poly(ether-etherketone)-grafted-poly(vinyl pyrrolidone)(PEEK-gPVP).The incorporation of protonic acid PW can enable the PEEK-g-PVP to be highly proton conductive and create flexible composite electrolyte membranes.Moreover,nanoscale phase separation between PEEK domains and PVP/PW domains spontaneously occurs in these membranes,forming a bicontinuous structure with three-dimensional(3D)-connected PW networks.Due to the dual role of PW networks as both proton transport pathways and mechanical enhancers,these membranes exhibit proton conductivities higher than 30 mS cm^(−1) and modulus over 4 GPa.Notably,the direct methanol fuel cells equipped with these membranes show good cell performance.Given the wide tunability of comb copolymers and polyoxometalates,this system can be extended to develop a variety of functional electrolyte materials,for example,the lithium-ion conductive electrolytes by using polyoxometalatebased lithium salts,which provides a promising platform to explore versatile electrolyte materials for energy and electronic applications.
