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Nafion

About: Nafion is a research topic. Over the lifetime, 9110 publications have been published within this topic receiving 320865 citations.


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Journal ArticleDOI
10 Aug 2011-ACS Nano
TL;DR: This research provides new insight into the rational design and fabrication of all-solid-state flexible energy-storage devices as well as the fundamental understanding of ion and charge transport at the interface.
Abstract: The realization of highly flexible and all-solid-state energy-storage devices strongly depends on both the electrical properties and mechanical integrity of the constitutive materials and the controlled assembly of electrode and solid electrolyte. Herein we report the preparation of all-solid-state flexible supercapacitors (SCs) through the easy assembly of functionalized reduced graphene oxide (f-RGO) thin films (as electrode) and solvent-cast Nafion electrolyte membranes (as electrolyte and separator). In particular, the f-RGO-based SCs (f-RGO-SCs) showed a 2-fold higher specific capacitance (118.5 F/g at 1 A/g) and rate capability (90% retention at 30 A/g) compared to those of all-solid-state graphene SCs (62.3 F/g at 1A/g and 48% retention at 30 A/g). As proven by the 4-fold faster relaxation of the f-RGO-SCs than that of the RGO-SCs and more capacitive behavior of the former at the low-frequency region, these results were attributed to the facilitated ionic transport at the electrical double layer by...

444 citations

Journal ArticleDOI
TL;DR: In this article, acceptor-doped rare earth ortho-niobates and ortho tantalates, RE1−xAxMO4 (M=Nb,Ta) were investigated and shown to have mixed protonic, native ionic and electronic conduction depending on conditions.
Abstract: Some oxides contain sufficient equilibrium concentrations of protons in wet atmospheres to show useful proton conduction at elevated temperatures1. As an example, Y-doped BaCeO3 has shown promising performance as a thin-film electrolyte in fuel cells at intermediate temperatures (400–600 ∘C)2. In contrast to proton-conducting polymers (for example, Nafion(R)) and acid salts (for example, CsHSO4), such oxidic ceramics are stable at sufficiently elevated temperatures that electrode kinetics are fast and insensitive to poisoning, but they tend to be basic (Ba-based or Sr-based) compounds with poor chemical and mechanical stability3. In search of more stable proton-conducting materials, we have investigated several acceptor-doped rare-earth ortho-niobates and ortho-tantalates, RE1−xAxMO4 (M=Nb,Ta). We show that this class of materials shows mixed protonic, native ionic and electronic conduction depending on conditions. Both the low-temperature monoclinic and high-temperature tetragonal polymorphs show proton conduction. The proton conductivity is dominant in wet atmospheres below roughly 800∘C and the highest proton conductivity of approximately 10−3Scm−1 was found for Ca-doped LaNbO4. These transport characteristics can be used in sensors and fuel cells provided that the electrolyte film thickness is in the micrometre range.

441 citations

Journal ArticleDOI
TL;DR: In this paper, the role of local chemistry of the hydrophilic side chains and its effect on the dissociation of the proton and eventual stableness is discussed in connection with their role in the conduction of protons in sulfonic acid-based polymer electrolyte membranes.
Abstract: ▪ Abstract The need to operate polymer electrolyte membrane (PEM) fuel cells at temperatures above 100°C, where the amount of water in the membrane is restricted, has provided much of the motivation for understanding the mechanisms of proton conduction at low degrees of hydration. Although experiments have not provided any direct information, numerous theoretical investigations have begun to provide the basis for understanding the mechanisms of proton conduction in these nano-phase-separated materials. Both the hydrated morphology and the nature of the confined water in the hydrophilic domains influence proton dissociation from the acidic sites (i.e., −SO3H), transfer to the water environment, and transport through the membrane. The following molecular processes are discussed in connection to their role in the conduction of protons in sulfonic acid–based polymer electrolyte membranes (PEMs): (a) local chemistry of the hydrophilic side chains; its effect on the dissociation of the proton and eventual stabi...

435 citations

Journal ArticleDOI
Jing Pan1, Chen Chen1, Yao Li1, Lei Wang1, Lisheng Tan1, Guangwei Li1, Xun Tang1, Li Xiao1, Juntao Lu1, Lin Zhuang1 
TL;DR: In this article, an ion-aggregating highway was constructed in the alkaline polymer electrolytes (APEs), such that the OH− conduction becomes as efficient as the H+ conduction in Nafion (greater than 0.1 S cm−1 at 80 °C under moderate ion exchange capacity.
Abstract: Alkaline polymer electrolytes (APEs) are an emerging material that enables the use of nonprecious-metal catalysts in electrochemical energy technology, such as fuel cell and water electrolysis. Yet the OH− conduction in APE has been of much lower efficiency than the H+ conduction in its acidic counterpart (typically Nafion), leading to a large dissipative loss in energy conversion applications. Here we report that, by properly constructing ion-aggregating structures in APE, a OH− conducting highway can be built, such that the OH− conduction in APE becomes as efficient as the H+ conduction in Nafion (greater than 0.1 S cm−1 at 80 °C under moderate ion-exchange capacity 1.0 mmol g−1). The optimal approach to constructing such an ionic highway is first screened computationally using coarse-grained molecular dynamics (CGMD) simulations, and then implemented experimentally based on a quaternary ammonia polysulfone (QAPS) model system. The resulting ordered structure of ion assembly has been unambiguously revealed by both the theoretically calculated structure factor and experimental results of TEM and SAXS. These findings have not only furthered our understanding about the ionic channels in APE, but also provided a general strategy for the rational design of polymer electrolytes.

432 citations

Journal ArticleDOI
TL;DR: The use of ring-opening metathesis polymerization is demonstrated to generate new cross-linked membrane materials exhibiting high hydroxide ion conductivity and good mechanical properties that have the potential to meet the demands of hydrogen-powered fuel cells as well as direct methanol fuel cells.
Abstract: Fuel cells are energy conversion devices that show great potential in numerous applications ranging from automobiles to portable electronics. However, further development of fuel cell components is necessary for them to become commercially viable. One component critical to their performance is the polymer electrolyte membrane, which is an ion conductive medium separating the two electrodes. While proton conducting membranes are well established (e.g., Nafion), hydroxide conducting membranes (alkaline anion exchange membranes, AAEMs) have been relatively unexplored by comparison. Operating under alkaline conditions offers significant efficiency benefits, especially for the oxygen reduction reaction; therefore, effective AAEMs could significantly advance fuel cell technologies. Here we demonstrate the use of ring-opening metathesis polymerization to generate new cross-linked membrane materials exhibiting high hydroxide ion conductivity and good mechanical properties. Cross-linking allows for increased ion incorporation, which, in turn supports high conductivities. This facile synthetic approach enables the preparation of cross-linked materials with the potential to meet the demands of hydrogen-powered fuel cells as well as direct methanol fuel cells.

429 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023253
2022503
2021338
2020367
2019386
2018393