{"title":"High-performance imidazole-containing polymers for applications in high temperature polymer electrolyte membrane fuel cells","authors":"","doi":"10.1016/j.jechem.2024.07.017","DOIUrl":null,"url":null,"abstract":"<div><p>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 <em>p</em>-terphenyl and aldehydes bearing imidazole moieties, resulting in a new class of HT-PEMs. It is found that the chemical structure of aldehyde-substituted <em>N</em>-heterocycles significantly impacts the polymerization reaction. Specifically, the use of 1-methyl-2-imidazole-formaldehyde and 1H-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 °C, 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<sup>−1</sup> at 180 °C. Under H<sub>2</sub>/O<sub>2</sub> operational conditions, a single cell based on the PTIm-a membrane attains a peak power density of 732 mW cm<sup>−2</sup> at 180 °C without backpressure. Furthermore, the membrane demonstrates stable cycle stability over 173 h within 18 days at a current density of 200 mA cm<sup>−2</sup>, 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.</p></div>","PeriodicalId":15728,"journal":{"name":"Journal of Energy Chemistry","volume":null,"pages":null},"PeriodicalIF":13.1000,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S209549562400490X/pdfft?md5=f39bfada1b23608c46ee26e25a4ef44e&pid=1-s2.0-S209549562400490X-main.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Energy Chemistry","FirstCategoryId":"92","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S209549562400490X","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"Energy","Score":null,"Total":0}
引用次数: 0
Abstract
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 1H-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 °C, 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 °C. Under H2/O2 operational conditions, a single cell based on the PTIm-a membrane attains a peak power density of 732 mW cm−2 at 180 °C 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.
期刊介绍:
The Journal of Energy Chemistry, the official publication of Science Press and the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, serves as a platform for reporting creative research and innovative applications in energy chemistry. It mainly reports on creative researches and innovative applications of chemical conversions of fossil energy, carbon dioxide, electrochemical energy and hydrogen energy, as well as the conversions of biomass and solar energy related with chemical issues to promote academic exchanges in the field of energy chemistry and to accelerate the exploration, research and development of energy science and technologies.
This journal focuses on original research papers covering various topics within energy chemistry worldwide, including:
Optimized utilization of fossil energy
Hydrogen energy
Conversion and storage of electrochemical energy
Capture, storage, and chemical conversion of carbon dioxide
Materials and nanotechnologies for energy conversion and storage
Chemistry in biomass conversion
Chemistry in the utilization of solar energy