This work focuses on the development of high temperature polymer electrolyte membranes(HT-PEMs)as key materials for HT-PEM fuel cells(HT-PEMFCs).Recognizing the challenges associated with the phosphoric acid(PA) doped...This work focuses on the development of high temperature polymer electrolyte membranes(HT-PEMs)as key materials for HT-PEM fuel cells(HT-PEMFCs).Recognizing the challenges associated with the phosphoric acid(PA) doped polybenzimidazole(PBI) membranes,including the use of carcinogenic monomers and complex synthesis procedures,this study aims to develop more cost-effective,readily synthesized,and high-performance alternatives.A series of superacid-catalyzed polyhydroxyalkylation reactions have been carefully designed between p-terphenyl and aldehydes bearing imidazole moieties,resulting in a new class of HT-PEMs.It is found that the chemical structure of aldehyde-substituted N-heterocycles significantly impacts the polymerization reaction.Specifically,the use of 1-methyl-2-imidazole-formaldehyde and 1 H-imidazole-4-formaldehyde monomers leads to the formation of high-viscosity,rigid,and ether-free polymers,denoted as PTIm-a and PTIm-b.Membranes fabricated from these polymers,due to their pendent imidazole groups,exhibit an exceptional capacity for PA absorption.Notably,PTIm-a,carrying methylimidazole moieties,demonstrates a superior chemical stability by maintaining morphology and structural stability during 350 h of Fenton testing.After being immersed in 75 wt% PA at 40℃,the PTIm-a membrane reaches a PA content of 152%,maintains a good tensile strength of 13.6 MPa,and exhibits a moderate conductivity of 50.2 mS cm^(-1) at 180℃.Under H_(2)/O_(2) operational conditions,a single cell based on the PTIm-a membrane attains a peak power density of 732 mW cm^(-2) at 180℃ without backpressure.Furthermore,the membrane demonstrates stable cycle stability over 173 h within 18 days at a current density of 200 mA cm^(-2),indicating its potential for practical application in HT-PEMFCs.This work highlights innovative strategies for the synthesis of advanced HT-PEMs,offering significant improvements in membrane properties and fuel cell performance,thus expanding the horizons of HT-PEMFC technology.展开更多
A new series of poly(arylene piperidinium)-based anion exchange membranes(AEMs)are proposed for vanadium redox flow batteries(VRFBs).The AEMs are fabricated via the Menshutkin reaction between poly(arylene piperidine)...A new series of poly(arylene piperidinium)-based anion exchange membranes(AEMs)are proposed for vanadium redox flow batteries(VRFBs).The AEMs are fabricated via the Menshutkin reaction between poly(arylene piperidine)without ether bonds in the backbone and various quaternizing agents,including iodomethane,1-bromopentane,and(5-bromopentyl)-trimethylammonium bromide.The properties of the AEMs are investigated in terms of sulfuric acid doping content,swelling,vanadium permeability,ion selectivity,area-specific resistance,mechanical properties,VRFB performance,and cyclic testing.Particularly,a method of measuring the H^(+) permeability of the AEM is developed.It demonstrates that the poly(p-terphenyl-N-methylpiperidine)-quaternary ammonium(PTP-QA)membrane with a QA cation-tethered alkyl chain exhibits high H^(+) permeability,resulting in low area resistance.Combined with its low vanadium permeance,the PTP-QA membrane achieves nearly 370 times higher ion selectivity than Nafion 115.The VRFB based on PTP-QA-based AEM displays high Coulombic efficiencies above 99% at current densities of 80-160 mA cm^(-2).The higher energy efficiency of 89.8% is achieved at 100 mA cm^(-2)(vs.73.6% for Nafion 115).Meanwhile,the PTPQA-based AEM shows good cycling stability and capacity retention,proving great potential as the ion exchange membrane for VRFB applications.展开更多
基金Natural Science Foundation of China (51603031)Liaoning Provincial Natural Science Foundation of China (2020-MS-087)China Scholarship Council(202306080157)。
文摘This work focuses on the development of high temperature polymer electrolyte membranes(HT-PEMs)as key materials for HT-PEM fuel cells(HT-PEMFCs).Recognizing the challenges associated with the phosphoric acid(PA) doped polybenzimidazole(PBI) membranes,including the use of carcinogenic monomers and complex synthesis procedures,this study aims to develop more cost-effective,readily synthesized,and high-performance alternatives.A series of superacid-catalyzed polyhydroxyalkylation reactions have been carefully designed between p-terphenyl and aldehydes bearing imidazole moieties,resulting in a new class of HT-PEMs.It is found that the chemical structure of aldehyde-substituted N-heterocycles significantly impacts the polymerization reaction.Specifically,the use of 1-methyl-2-imidazole-formaldehyde and 1 H-imidazole-4-formaldehyde monomers leads to the formation of high-viscosity,rigid,and ether-free polymers,denoted as PTIm-a and PTIm-b.Membranes fabricated from these polymers,due to their pendent imidazole groups,exhibit an exceptional capacity for PA absorption.Notably,PTIm-a,carrying methylimidazole moieties,demonstrates a superior chemical stability by maintaining morphology and structural stability during 350 h of Fenton testing.After being immersed in 75 wt% PA at 40℃,the PTIm-a membrane reaches a PA content of 152%,maintains a good tensile strength of 13.6 MPa,and exhibits a moderate conductivity of 50.2 mS cm^(-1) at 180℃.Under H_(2)/O_(2) operational conditions,a single cell based on the PTIm-a membrane attains a peak power density of 732 mW cm^(-2) at 180℃ without backpressure.Furthermore,the membrane demonstrates stable cycle stability over 173 h within 18 days at a current density of 200 mA cm^(-2),indicating its potential for practical application in HT-PEMFCs.This work highlights innovative strategies for the synthesis of advanced HT-PEMs,offering significant improvements in membrane properties and fuel cell performance,thus expanding the horizons of HT-PEMFC technology.
基金supported by the National Natural Science Foundation of China(51603031)the Fundamental Research Funds for the Central Universities of China(N2005026)+1 种基金Liaoning Provincial Natural Science Foundation of China(20180550871 and 2020-MS-087)the Innovation Fund Denmark(DanFlow)。
文摘A new series of poly(arylene piperidinium)-based anion exchange membranes(AEMs)are proposed for vanadium redox flow batteries(VRFBs).The AEMs are fabricated via the Menshutkin reaction between poly(arylene piperidine)without ether bonds in the backbone and various quaternizing agents,including iodomethane,1-bromopentane,and(5-bromopentyl)-trimethylammonium bromide.The properties of the AEMs are investigated in terms of sulfuric acid doping content,swelling,vanadium permeability,ion selectivity,area-specific resistance,mechanical properties,VRFB performance,and cyclic testing.Particularly,a method of measuring the H^(+) permeability of the AEM is developed.It demonstrates that the poly(p-terphenyl-N-methylpiperidine)-quaternary ammonium(PTP-QA)membrane with a QA cation-tethered alkyl chain exhibits high H^(+) permeability,resulting in low area resistance.Combined with its low vanadium permeance,the PTP-QA membrane achieves nearly 370 times higher ion selectivity than Nafion 115.The VRFB based on PTP-QA-based AEM displays high Coulombic efficiencies above 99% at current densities of 80-160 mA cm^(-2).The higher energy efficiency of 89.8% is achieved at 100 mA cm^(-2)(vs.73.6% for Nafion 115).Meanwhile,the PTPQA-based AEM shows good cycling stability and capacity retention,proving great potential as the ion exchange membrane for VRFB applications.
