The Use of Heteropoly Acids in Proton Exchange Fuel Cells

Sachdeva, Sonny; Turner, John A.; Horan, James L.; Herring, Andrew M.

doi:10.1007/430_2011_45

Cited by 23 publications

(12 citation statements)

References 164 publications

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“…HPAs usually crystallize with a large number of water molecules and form the secondary structure, resulting in the formation of new active species such as the [H 3 O] + and the [H 5 O 2 ] + ions (Figure 2) [12,23]. The heteropolyanions are quite mobile in HPA crystals.…”

Section: Advantages Of Polyoxometalates (Poms) In Proton Exchange mentioning

confidence: 99%

“…When 0< n < 6, acidic protons are located randomly (may be in H 5 O 2 + bridges, H 3 O + or bonded to the oxygens of the Keggin unit); when n = 6, the acidic protons are located in the central H 5 O 2 + bridges between lattice points. Reproduced with permission from [12]. Copyright (2011) Springer.…”

Section: Figurementioning

confidence: 99%

“…One of the main groups of POMs, heteropolyacids (HPAs), displaying strong Brönsted acidity and the highest proton conductivity in their fully hydrated state among inorganic solids near ambient temperatures, are promising candidates for fabricating composite PEMs. A large number of bonded water molecules, high thermal stability, structural flexibility and mobility of HPAs are beneficial for fuel cell applications as well [11,12,13,14]. Nevertheless, the high water solubility of HPAs leading to the progressive leakage from membranes and the decrease of proton conductivity is a well-recognized obstacle to using HPA-based PEMs.…”

Section: Introductionmentioning

confidence: 99%

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Polyoxometalate–Polymer Hybrid Materials as Proton Exchange Membranes for Fuel Cell Applications

Zhai

2019

Molecules

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As one of the most efficient pathways to provide clean energy, fuel cells have attracted great attention in both academic and industrial communities. Proton exchange membranes (PEMs) or proton-conducting electrolytes are the key components in fuel cell devices, which require the characteristics of high proton conductivity as well as high mechanical, chemical and thermal stabilities. Organic–inorganic hybrid PEMs can provide a fantastic platform to combine both advantages of two components to meet these demands. Due to their extremely high proton conductivity, good thermal stability and chemical adjustability, polyoxometalates (POMs) are regarded as promising building blocks for hybrid PEMs. In this review, we summarize a number of research works on the progress of POM–polymer hybrid materials and related applications in PEMs. Firstly, a brief background of POMs and their proton-conducting properties are introduced; then, the hybridization strategies of POMs with polymer moieties are discussed from the aspects of both noncovalent and covalent concepts; and finally, we focus on the performance of these hybrid materials in PEMs, especially the advances in the last five years. This review will provide a better understanding of the challenges and perspectives of POM–polymer hybrid PEMs for future fuel cell applications.

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Section: Advantages Of Polyoxometalates (Poms) In Proton Exchange mentioning

confidence: 99%

Section: Figurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Polyoxometalate–Polymer Hybrid Materials as Proton Exchange Membranes for Fuel Cell Applications

Zhai

2019

Molecules

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“…The conductivity of the non-aqueous electrolyte was chosen to be 0.02 S cm −1 and the thickness was chosen to be 0.025 cm. The conductivity was based on a recent literature report 61 although the generic nature of our model means that the choice of non-aqueous electrolyte is arbitrary and we need only account for certain parameters like conductivity and density. We have simulated the power density-energy curves for the hybrid asymmetric capacitor using the non-aqueous electrolyte over a voltage window of 4.2 V. The results in Figure 6 closely follow the trends observed in Figure 5.…”

Section: E3273mentioning

confidence: 99%

Mathematical Modeling of Hybrid Asymmetric Electrochemical Capacitors

Weidner

2014

J. Electrochem. Soc.

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Electrochemical capacitors may be ideal energy storage devices for applications ranging from renewable energy storage to transportation. Electrochemical capacitors are characterized by high power density and cycle life, and can be classified based on the properties of their electrodes. Symmetric capacitors have two electrodes that exhibit the same behavior, while asymmetric capacitors have two electrodes that exhibit different behavior. A hybrid asymmetric capacitor is a device that has two electrodes that behave differently because of different processes occurring in them. In this paper, we present a mathematical model of hybrid asymmetric capacitors made up of a redox couple electrode and a double-layer electrode. We show that, because of the different behavior of each electrode, the hybrid asymmetric capacitor possesses higher energy and power density than the symmetric capacitor. Our model is generic and can be extended to any device so long as the properties of the electrodes are known. Electrochemical energy storage systems like electrochemical capacitors may be ideal to meet the needs of renewable energy storage and electric vehicles.1-3 Electrochemical capacitors are characterized by high power density and high cycle life. In the simplest terms, electrochemical capacitors store energy in the double layer at the interface of an electrically conductive material and the electrolyte. No faradaic reaction occurs. Double layer capacitance is low, usually between 10 and 40 μF cm −2 of electrode surface area. Therefore, high surface area materials are used (e.g., porous carbon electrodes) to significantly increase the capacitance of the device. 4 Because the voltage across a double layer is proportional to the charge stored, the voltage of a device decreases linearly with time during an entire constant-current discharge. In contrast, the voltage across a device where a faradaic reaction occurs across the electrode/electrolyte interface (i.e., a battery) is determined by the activity of the reactants and products. Therefore, its constant-current discharge curve is sigmoidal in shape, and hence the voltage is fairly constant over a significant portion of the discharge. Finally, pseudocapacitance is a term used to describe storage of charge via faradaic reactions where the activities of reactants and products are such that the discharge curve of a device more closely resembles a capacitor than it does a battery. Although pseudocapacitor response is much like a double-layer capacitor, they have considerably higher capacitance, and hence energy.Regardless of the type of device (i.e., double-layer capacitor or pseudocapacitor), the term "capacitor" is valid when the electrodes behave like a capacitor. Major efforts related to double-layer capacitors have focused on understanding the effect of electrode thickness and pore structure on the energy density and device capacity. 5-7Efforts toward developing pseudocapacitors have mostly focused on creating different electrode materials with most emphasis given to metal oxide...

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“…Incorporation of hydrophilic oxides was pursued extensively, and the introduction of inorganic proton donors into the polymer electrolyte matrix increases various properties of the polymer electrolyte such as proton conductivity, thermal stability, and therefore, it gained a lot of attention due to their excellent performance in various aspects. Recently, organic–inorganic hybrid materials based on polymers and inorganic proton‐conductors, such as heteropoly acids (HPAs), have been considered as electrolyte membranes for fuel cell operations …”

Section: Introductionmentioning

confidence: 99%

Proton‐conductive membranes based on vanadium substituted heteropoly acids with Keggin structure and polymers

Tian

Yang

et al. 2015

J of Applied Polymer Sci

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In this article, novel proton-conducting composite membranes SPEEK/PW 11 V and PVA/SiW 11 V were synthesized from vanadium substituted heteropoly acids (H 4 PW 11 VO 40 Á8H 2 O and H 5 SiW 11 VO 40 Á15H 2 O, abbreviated as PW 11 V and SiW 11 V) and polymers (SPEEK or PVA) at the weight ratio 70 : 30. The membranes were characterized by the infrared spectroscopy, X-ray powder diffraction, and scanning electron microscopy, which confirmed the maintenance of the Keggin framework and dispersion homogeneously in the polymer matrix without long-range ordering. Their proton-conducting properties were investigated with electrochemical impedance spectroscopy. The results show that the respective proton conductivities of SPEEK/PW 11 V and PVA/SiW 11 V membranes were in the order of 10 22 and 10 24 S cm 21 at ambient temperature. The temperature dependence of the two composite membrane electrolytes exhibit Arrhenius behavior, and the observed activation energies to be 15.82 kJ mol 21 for SPEEK/PW 11 V and 14.40 kJ mol 21 for PVA/SiW 11 V, which indicates that the proton conduction complies with the Grotthuss mechanism. V C 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42204.

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The Use of Heteropoly Acids in Proton Exchange Fuel Cells

Cited by 23 publications

References 164 publications

Polyoxometalate–Polymer Hybrid Materials as Proton Exchange Membranes for Fuel Cell Applications

Polyoxometalate–Polymer Hybrid Materials as Proton Exchange Membranes for Fuel Cell Applications

Mathematical Modeling of Hybrid Asymmetric Electrochemical Capacitors

Proton‐conductive membranes based on vanadium substituted heteropoly acids with Keggin structure and polymers

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