Special Issue "Membranes for Electrochemical Energy Applications"

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A special issue of Membranes (ISSN 2077-0375). This special issue belongs to the section "Membrane Processes (Applications)".

Deadline for manuscript submissions: closed (30 April 2012)

Special Issue Editor

Guest Editor
Prof. Dr. Bruno Scrosati

Department of Chemistry, University Sapienza, Piazzale Aldo Moro 5, 00185 Rome, Italy
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Interests: polymer electrolyte membrane fuel cells; lithium polymer batteries

Special Issue Information

Dear Colleagues,

Membranes play a key role in energy-related fields since they are the main components of devices which could help address one of the most serious threats to our society, namely global warming. Serious concern is associated with the continuous CO2 emission resulting from our energy policy, which is still mainly based on burning of fossil fuels. Accordingly, an efficient use of renewable energy sources and the replacement of internal combustion engines with electric motors for the development of sustainable vehicles, such as hybrid vehicles (HEVs), plug-in hybrid vehicles (PHEVs) and ultimately, full electric vehicles (EVs), are major goals in the present energy scenario. On the other hand, an efficient use of alternative, green, energy sources, such as solar and wind, requires the side support of energy storage systems that can compensate for their intermittent characteristics. Analogously, HEVs, PHEVs and EVs require an on-board energy source for powering the electric engine. Among the various choices, electrochemical devices, such as fuel cells and batteries, capable of delivering stored chemical energy as electrical energy with high conversion efficiency and without any gaseous emission, are the most suitable. Moreover, fuel cells and batteries offer a promising option to efficiently power the electric engine in HEVs or EVs.

The most common and most studied fuel cells utilize a perfluorosulfonic membrane electrolyte, mainly of the NAFION® type. Although becoming increasingly well-known over time, these membranes still require attention to further improve performance. Much research is presently being carried out in this area, and this Special Issue will be a perfect forum to bring together the latest results obtained by key laboratories presently engaged in polymer electrolyte membrane fuel cell R&D.

In terms of battery research, particular interest is focused on lithium batteries due to their intrinsic, high energy density value. However, in their present configuration, lithium batteries are affected by a series of issues that still prevent their wide use for electric vehicle application. One of the most serious is the safety concern associated with the unstable and flammable nature of the common liquid electrolytes. Improving safety is thus a present challenge in the field. One approach to reach this goal is to move away from the unreliable liquid, organic electrolytes, to stable and safe polymer electrolyte membranes. There are two classes of these membranes: a polymer-liquid hybrid type, generally named gel-type membranes, and membranes formed by liquid-free combinations of polymer with lithium salts, generally named solid polymer electrolytes. Today there is tremendous research ongoing worldwide is involved into lithium batteries, motivated by a large amount of funding granted in many countries. Therefore, breakthroughs in the area―especially in membrane electrolyte and related polymer batteries―are expected to soon concretize. Again, this Special Issue offers a perfect site for welcoming the latest innovations, and accordingly authors from top laboratories are invited to submit their latest results.

Prof. Dr. Bruno Scrosati
Guest Editor

Keywords

  • hydrogen conducting membranes
  • perfluorosulfonic membranes
  • fuel cells
  • lithium conducting membranes
  • gel-type membranes
  • solvent-free, solid-state membranes
  • lithium batteries

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Published Papers (17 papers)

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Research

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Open AccessArticle Microscopic Analysis of Current and Mechanical Properties of Nafion® Studied by Atomic Force Microscopy
Membranes 2012, 2(4), 783-803; doi:10.3390/membranes2040783
Received: 9 July 2012 / Revised: 3 October 2012 / Accepted: 31 October 2012 / Published: 16 November 2012
Cited by 16 | PDF Full-text (6391 KB) | HTML Full-text | XML Full-text
Abstract
The conductivity of fuel cell membranes as well as their mechanical properties at the nanometer scale were characterized using advanced tapping mode atomic force microscopy (AFM) techniques. AFM produces high-resolution images under continuous current flow of the conductive structure at the membrane surface
[...] Read more.
The conductivity of fuel cell membranes as well as their mechanical properties at the nanometer scale were characterized using advanced tapping mode atomic force microscopy (AFM) techniques. AFM produces high-resolution images under continuous current flow of the conductive structure at the membrane surface and provides some insight into the bulk conducting network in Nafion membranes. The correlation of conductivity with other mechanical properties, such as adhesion force, deformation and stiffness, were simultaneously measured with the current and provided an indication of subsurface phase separations and phase distribution at the surface of the membrane. The distribution of conductive pores at the surface was identified by the formation of water droplets. A comparison of nanostructure models with high-resolution current images is discussed in detail. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
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Open AccessArticle Plasma Membranes Modified by Plasma Treatment or Deposition as Solid Electrolytes for Potential Application in Solid Alkaline Fuel Cells
Membranes 2012, 2(3), 529-552; doi:10.3390/membranes2030529
Received: 25 May 2012 / Revised: 29 June 2012 / Accepted: 11 July 2012 / Published: 30 July 2012
Cited by 7 | PDF Full-text (559 KB) | HTML Full-text | XML Full-text
Abstract
In the highly competitive market of fuel cells, solid alkaline fuel cells using liquid fuel (such as cheap, non-toxic and non-valorized glycerol) and not requiring noble metal as catalyst seem quite promising. One of the main hurdles for emergence of such a technology
[...] Read more.
In the highly competitive market of fuel cells, solid alkaline fuel cells using liquid fuel (such as cheap, non-toxic and non-valorized glycerol) and not requiring noble metal as catalyst seem quite promising. One of the main hurdles for emergence of such a technology is the development of a hydroxide-conducting membrane characterized by both high conductivity and low fuel permeability. Plasma treatments can enable to positively tune the main fuel cell membrane requirements. In this work, commercial ADP-Morgane® fluorinated polymer membranes and a new brand of cross-linked poly(aryl-ether) polymer membranes, named AMELI-32®, both containing quaternary ammonium functionalities, have been modified by argon plasma treatment or triallylamine-based plasma deposit. Under the concomitant etching/cross-linking/oxidation effects inherent to the plasma modification, transport properties (ionic exchange capacity, water uptake, ionic conductivity and fuel retention) of membranes have been improved. Consequently, using plasma modified ADP-Morgane® membrane as electrolyte in a solid alkaline fuel cell operating with glycerol as fuel has allowed increasing the maximum power density by a factor 3 when compared to the untreated membrane. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
Open AccessArticle Proton Content and Nature in Perovskite Ceramic Membranes for Medium Temperature Fuel Cells and Electrolysers
Membranes 2012, 2(3), 493-509; doi:10.3390/membranes2030493
Received: 28 April 2012 / Revised: 8 June 2012 / Accepted: 28 June 2012 / Published: 25 July 2012
Cited by 12 | PDF Full-text (1338 KB) | HTML Full-text | XML Full-text
Abstract
Recent interest in environmentally friendly technology has promoted research on green house gas-free devices such as water steam electrolyzers, fuel cells and CO2/syngas converters. In such applications, proton conducting perovskite ceramics appear especially promising as electrolyte membranes. Prior to a successful
[...] Read more.
Recent interest in environmentally friendly technology has promoted research on green house gas-free devices such as water steam electrolyzers, fuel cells and CO2/syngas converters. In such applications, proton conducting perovskite ceramics appear especially promising as electrolyte membranes. Prior to a successful industrial application, it is necessary to determine/understand their complex physical and chemical behavior, especially that related to proton incorporation mechanism, content and nature of bulk protonic species. Based on the results of quasi-elastic neutron scattering (QNS), thermogravimetric analysis (TGA), Raman and IR measurements we will show the complexity of the protonation process and the importance of differentiation between the protonic species adsorbed on a membrane surface and the bulk protons. The bulk proton content is very low, with a doping limit (~1–5 × 10−3 mole/mole), but sufficient to guarantee proton conduction below 600 °C. The bulk protons posses an ionic, covalent bond free nature and may occupy an interstitial site in the host perovskite structure. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
Open AccessArticle Anion- or Cation-Exchange Membranes for NaBH4/H2O2 Fuel Cells?
Membranes 2012, 2(3), 478-492; doi:10.3390/membranes2030478
Received: 7 May 2012 / Revised: 21 June 2012 / Accepted: 9 July 2012 / Published: 19 July 2012
Cited by 6 | PDF Full-text (901 KB) | HTML Full-text | XML Full-text
Abstract
Direct borohydride fuel cells (DBFC), which operate on sodium borohydride (NaBH4) as the fuel, and hydrogen peroxide (H2O2) as the oxidant, are receiving increasing attention. This is due to their promising use as power sources for space
[...] Read more.
Direct borohydride fuel cells (DBFC), which operate on sodium borohydride (NaBH4) as the fuel, and hydrogen peroxide (H2O2) as the oxidant, are receiving increasing attention. This is due to their promising use as power sources for space and underwater applications, where air is not available and gas storage poses obvious problems. One key factor to improve the performance of DBFCs concerns the type of separator used. Both anion- and cation-exchange membranes may be considered as potential separators for DBFC. In the present paper, the effect of the membrane type on the performance of laboratory NaBH4/H2O2 fuel cells using Pt electrodes is studied at room temperature. Two commercial ion-exchange membranes from Membranes International Inc., an anion-exchange membrane (AMI-7001S) and a cation-exchange membrane (CMI-7000S), are tested as ionic separators for the DBFC. The membranes are compared directly by the observation and analysis of the corresponding DBFC’s performance. Cell polarization, power density, stability, and durability tests are used in the membranes’ evaluation. Energy densities and specific capacities are estimated. Most tests conducted, clearly indicate a superior performance of the cation-exchange membranes over the anion-exchange membrane. The two membranes are also compared with several other previously tested commercial membranes. For long term cell operation, these membranes seem to outperform the stability of the benchmark Nafion membranes but further studies are still required to improve their instantaneous power load. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
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Open AccessArticle Poly(imide)/Organically-Modified Montmorillonite Nanocomposite as a Potential Membrane for Alkaline Fuel Cells
Membranes 2012, 2(3), 430-439; doi:10.3390/membranes2030430
Received: 7 May 2012 / Revised: 19 June 2012 / Accepted: 4 July 2012 / Published: 18 July 2012
Cited by 5 | PDF Full-text (1080 KB) | HTML Full-text | XML Full-text
Abstract
In this work we evaluated the potentiality of a poly(imide) (PI)/organically-modified montmorillonite (O-MMT) nanocomposite membrane for the use in alkaline fuel cells. Both X-ray diffraction and scanning electron microscopy revealed a good dispersion of O-MMT into the PI matrix and preservation of the
[...] Read more.
In this work we evaluated the potentiality of a poly(imide) (PI)/organically-modified montmorillonite (O-MMT) nanocomposite membrane for the use in alkaline fuel cells. Both X-ray diffraction and scanning electron microscopy revealed a good dispersion of O-MMT into the PI matrix and preservation of the O-MMT layered structure. When compared to the pure PI, the addition of O-MMT improved thermal stability and markedly increased the capability of absorbing electrolyte and ionic conductivity of the composite. The results show that the PI/O-MMT nanocomposite is a promising candidate for alkaline fuel cell applications. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
Open AccessArticle A Composite Membrane of Caesium Salt of Heteropolyacids/Quaternary Diazabicyclo-Octane Polysulfone with Poly (Tetrafluoroethylene) for Intermediate Temperature Fuel Cells
Membranes 2012, 2(3), 384-394; doi:10.3390/membranes2030384
Received: 8 May 2012 / Revised: 7 June 2012 / Accepted: 28 June 2012 / Published: 10 July 2012
Cited by 1 | PDF Full-text (647 KB) | HTML Full-text | XML Full-text
Abstract
Inorganic-organic composite electrolyte membranes were fabricated from CsXH3−XPMo12O40 (CsPOMo) and quaternary diazabicyclo-octane polysulfone (QDPSU) using a polytetrafluoroethylene (PTFE) porous matrix for the application of intermediate temperature fuel cells. The CsPOMo/QDPSU/PTFE composite membrane was made proton conducting
[...] Read more.
Inorganic-organic composite electrolyte membranes were fabricated from CsXH3−XPMo12O40 (CsPOMo) and quaternary diazabicyclo-octane polysulfone (QDPSU) using a polytetrafluoroethylene (PTFE) porous matrix for the application of intermediate temperature fuel cells. The CsPOMo/QDPSU/PTFE composite membrane was made proton conducting by using a relatively low phosphoric acid loading, which benefits the stability of the membrane conductivity and the mechanical strength. The casting method was used in order to build a thin and robust composite membrane. The resulting composite membrane films were characterised in terms of the elemental composition, membrane structure and morphology by EDX, FTIR and SEM. The proton conductivity of the membrane was 0.04 S cm−1 with a H3PO4 loading level of 1.8 PRU (amount of H3PO4 per repeat unit of polymer QDPSU). The fuel cell performance with the membrane gave a peak power density of 240 mW cm−2 at 150 °C and atmospheric pressure. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
Open AccessArticle NMR and Electrochemical Investigation of the Transport Properties of Methanol and Water in Nafion and Clay-Nanocomposites Membranes for DMFCs
Membranes 2012, 2(2), 325-345; doi:10.3390/membranes2020325
Received: 18 May 2012 / Revised: 8 June 2012 / Accepted: 12 June 2012 / Published: 20 June 2012
Cited by 8 | PDF Full-text (953 KB) | HTML Full-text | XML Full-text
Abstract
Water and methanol transport behavior, solvents adsorption and electrochemical properties of filler-free Nafion and nanocomposites based on two smectite clays, were investigated using impedance spectroscopy, DMFC tests and NMR methods, including spin-lattice relaxation and pulsed-gradient spin-echo (PGSE) diffusion under variable temperature conditions. Synthetic
[...] Read more.
Water and methanol transport behavior, solvents adsorption and electrochemical properties of filler-free Nafion and nanocomposites based on two smectite clays, were investigated using impedance spectroscopy, DMFC tests and NMR methods, including spin-lattice relaxation and pulsed-gradient spin-echo (PGSE) diffusion under variable temperature conditions. Synthetic (Laponite) and natural (Swy-2) smectite clays, with different structural and physical parameters, were incorporated into the Nafion for the creation of exfoliated nanocomposites. Transport mechanism of water and methanol appears to be influenced from the dimensions of the dispersed platelike silicate layers as well as from their cation exchange capacity (CEC). The details of the NMR results and the effect of the methanol solution concentration are discussed. Clays particles, and in particular Swy-2, demonstrate to be a potential physical barrier for methanol cross-over, reducing the methanol diffusion with an evident blocking effect yet nevertheless ensuring a high water mobility up to 130 °C and for several hours, proving the exceptional water retention property of these materials and their possible use in the DMFCs applications. Electrochemical behavior is investigated by cell resistance and polarization measurements. From these analyses it is derived that the addition of clay materials to recast Nafion decreases the ohmic losses at high temperatures extending in this way the operating range of a direct methanol fuel cell. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
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Open AccessArticle UV-Induced Radical Photo-Polymerization: A Smart Tool for Preparing Polymer Electrolyte Membranes for Energy Storage Devices
Membranes 2012, 2(2), 307-324; doi:10.3390/membranes2020307
Received: 28 April 2012 / Revised: 29 May 2012 / Accepted: 7 June 2012 / Published: 19 June 2012
Cited by 2 | PDF Full-text (502 KB) | HTML Full-text | XML Full-textRetraction
Abstract
In the present work, the preparation and characterization of quasi-solid polymer electrolyte membranes based on methacrylic monomers and oligomers, with the addition of organic plasticizers and lithium salt, are described. Noticeable improvements in the mechanical properties by reinforcement with natural cellulose hand-sheets or
[...] Read more.
In the present work, the preparation and characterization of quasi-solid polymer electrolyte membranes based on methacrylic monomers and oligomers, with the addition of organic plasticizers and lithium salt, are described. Noticeable improvements in the mechanical properties by reinforcement with natural cellulose hand-sheets or nanoscale microfibrillated cellulose fibers are also demonstrated. The ionic conductivity of the various prepared membranes is very high, with average values approaching 10-3 S cm-1 at ambient temperature. The electrochemical stability window is wide (anodic breakdown voltages > 4.5 V vs. Li in all the cases) along with good cyclability in lithium cells at ambient temperature. The galvanostatic cycling tests are conducted by constructing laboratory-scale lithium cells using LiFePO4 as cathode and lithium metal as anode with the selected polymer electrolyte membrane as the electrolyte separator. The results obtained demonstrate that UV induced radical photo-polymerization is a well suited method for an easy and rapid preparation of easy tunable quasi-solid polymer electrolyte membranes for energy storage devices. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
Open AccessArticle Synthesis, Multinuclear NMR Characterization and Dynamic Property of Organic–Inorganic Hybrid Electrolyte Membrane Based on Alkoxysilane and Poly(oxyalkylene) Diamine
Membranes 2012, 2(2), 253-274; doi:10.3390/membranes2020253
Received: 27 April 2012 / Revised: 1 June 2012 / Accepted: 4 June 2012 / Published: 13 June 2012
Cited by 4 | PDF Full-text (1124 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Organic–inorganic hybrid electrolyte membranes based on poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) bis(2-aminopropyl ether) complexed with LiClO4 via the co-condensation of tetraethoxysilane (TEOS) and 3-(triethoxysilyl)propyl isocyanate have been prepared and characterized. A variety of techniques such as differential scanning calorimetry
[...] Read more.
Organic–inorganic hybrid electrolyte membranes based on poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) bis(2-aminopropyl ether) complexed with LiClO4 via the co-condensation of tetraethoxysilane (TEOS) and 3-(triethoxysilyl)propyl isocyanate have been prepared and characterized. A variety of techniques such as differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, alternating current (AC) impedance and solid-state nuclear magnetic resonance (NMR) spectroscopy are performed to elucidate the relationship between the structural and dynamic properties of the hybrid electrolyte and the ion mobility. A VTF (Vogel-Tamman-Fulcher)-like temperature dependence of ionic conductivity is observed for all the compositions studied, implying that the diffusion of charge carriers is assisted by the segmental motions of the polymer chains. A maximum ionic conductivity value of 5.3 × 10−5 Scm−1 is obtained at 30 °C. Solid-state NMR results provide a microscopic view of the effects of salt concentrations on the dynamic behavior of the polymer chains. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
Open AccessArticle Impedance Spectroscopic Investigation of Proton Conductivity in Nafion Using Transient Electrochemical Atomic Force Microscopy (AFM)
Membranes 2012, 2(2), 237-252; doi:10.3390/membranes2020237
Received: 25 April 2012 / Revised: 25 May 2012 / Accepted: 29 May 2012 / Published: 6 June 2012
Cited by 5 | PDF Full-text (648 KB) | HTML Full-text | XML Full-text
Abstract
Spatially resolved impedance spectroscopy of a Nafion polyelectrolyte membrane is performed employing a conductive and Pt-coated tip of an atomic force microscope as a point-like contact and electrode. The experiment is conducted by perturbing the system by a rectangular voltage step and measuring
[...] Read more.
Spatially resolved impedance spectroscopy of a Nafion polyelectrolyte membrane is performed employing a conductive and Pt-coated tip of an atomic force microscope as a point-like contact and electrode. The experiment is conducted by perturbing the system by a rectangular voltage step and measuring the incurred current, followed by Fourier transformation and plotting the impedance against the frequency in a conventional Bode diagram. To test the potential and limitations of this novel method, we present a feasibility study using an identical hydrogen atmosphere at a well-defined relative humidity on both sides of the membrane. It is demonstrated that good quality impedance spectra are obtained in a frequency range of 0.2–1,000 Hz. The extracted polarization curves exhibit a maximum current which cannot be explained by typical diffusion effects. Simulation based on equivalent circuits requires a Nernst element for restricted diffusion in the membrane which suggests that this effect is based on the potential dependence of the electrolyte resistance in the high overpotential region. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)

Review

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Open AccessReview U.S. DOE Progress Towards Developing Low-Cost, High Performance, Durable Polymer Electrolyte Membranes for Fuel Cell Applications
Membranes 2012, 2(4), 855-878; doi:10.3390/membranes2040855
Received: 26 October 2012 / Revised: 6 December 2012 / Accepted: 7 December 2012 / Published: 18 December 2012
Cited by 23 | PDF Full-text (2128 KB) | HTML Full-text | XML Full-text
Abstract
Low cost, durable, and selective membranes with high ionic conductivity are a priority need for wide-spread adoption of polymer electrolyte membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs). Electrolyte membranes are a major cost component of PEMFC stacks at low production
[...] Read more.
Low cost, durable, and selective membranes with high ionic conductivity are a priority need for wide-spread adoption of polymer electrolyte membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs). Electrolyte membranes are a major cost component of PEMFC stacks at low production volumes. PEMFC membranes also impose limitations on fuel cell system operating conditions that add system complexity and cost. Reactant gas and fuel permeation through the membrane leads to decreased fuel cell performance, loss of efficiency, and reduced durability in both PEMFCs and DMFCs. To address these challenges, the U.S. Department of Energy (DOE) Fuel Cell Technologies Program, in the Office of Energy Efficiency and Renewable Energy, supports research and development aimed at improving ion exchange membranes for fuel cells. For PEMFCs, efforts are primarily focused on developing materials for higher temperature operation (up to 120 °C) in automotive applications. For DMFCs, efforts are focused on developing membranes with reduced methanol permeability. In this paper, the recently revised DOE membrane targets, strategies, and highlights of DOE-funded projects to develop new, inexpensive membranes that have good performance in hot and dry conditions (PEMFC) and that reduce methanol crossover (DMFC) will be discussed. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
Open AccessReview A Review of RedOx Cycling of Solid Oxide Fuel Cells Anode
Membranes 2012, 2(3), 585-664; doi:10.3390/membranes2030585
Received: 14 June 2012 / Revised: 16 July 2012 / Accepted: 17 July 2012 / Published: 31 August 2012
Cited by 42 | PDF Full-text (6038 KB) | HTML Full-text | XML Full-text
Abstract
Solid oxide fuel cells are able to convert fuels, including hydrocarbons, to electricity with an unbeatable efficiency even for small systems. One of the main limitations for long-term utilization is the reduction-oxidation cycling (RedOx cycles) of the nickel-based anodes. This paper will review
[...] Read more.
Solid oxide fuel cells are able to convert fuels, including hydrocarbons, to electricity with an unbeatable efficiency even for small systems. One of the main limitations for long-term utilization is the reduction-oxidation cycling (RedOx cycles) of the nickel-based anodes. This paper will review the effects and parameters influencing RedOx cycles of the Ni-ceramic anode. Second, solutions for RedOx instability are reviewed in the patent and open scientific literature. The solutions are described from the point of view of the system, stack design, cell design, new materials and microstructure optimization. Finally, a brief synthesis on RedOx cycling of Ni-based anode supports for standard and optimized microstructures is depicted. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
Open AccessReview Electrochemical Membrane Reactors for Sustainable Chlorine Recycling
Membranes 2012, 2(3), 510-528; doi:10.3390/membranes2030510
Received: 23 May 2012 / Revised: 29 June 2012 / Accepted: 4 July 2012 / Published: 30 July 2012
Cited by 9 | PDF Full-text (1338 KB) | HTML Full-text | XML Full-text
Abstract
Polymer electrolyte membranes have found broad application in a number of processes, being fuel cells, due to energy concerns, the main focus of the scientific community worldwide. Relatively little attention has been paid to the use of these materials in electrochemical production and
[...] Read more.
Polymer electrolyte membranes have found broad application in a number of processes, being fuel cells, due to energy concerns, the main focus of the scientific community worldwide. Relatively little attention has been paid to the use of these materials in electrochemical production and separation processes. In this review, we put emphasis upon the application of Nafion membranes in electrochemical membrane reactors for chlorine recycling. The performance of such electrochemical reactors can be influenced by a number of factors including the properties of the membrane, which play an important role in reactor optimization. This review discusses the role of Nafion as a membrane, as well as its importance in the catalyst layer for the formation of the so-called three-phase boundary. The influence of an equilibrated medium on the Nafion proton conductivity and Cl crossover, as well as the influence of the catalyst ink dispersion medium on the Nafion/catalyst self-assembly and its importance for the formation of an ionic conducting network in the catalyst layer are summarized. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
Open AccessReview A Review of Molecular-Level Mechanism of Membrane Degradation in the Polymer Electrolyte Fuel Cell
Membranes 2012, 2(3), 395-414; doi:10.3390/membranes2030395
Received: 30 April 2012 / Revised: 18 June 2012 / Accepted: 27 June 2012 / Published: 10 July 2012
Cited by 7 | PDF Full-text (751 KB) | HTML Full-text | XML Full-text
Abstract
Chemical degradation of perfluorosulfonic acid (PFSA) membrane is one of the most serious problems for stable and long-term operations of the polymer electrolyte fuel cell (PEFC). The chemical degradation is caused by the chemical reaction between the PFSA membrane and chemical species such
[...] Read more.
Chemical degradation of perfluorosulfonic acid (PFSA) membrane is one of the most serious problems for stable and long-term operations of the polymer electrolyte fuel cell (PEFC). The chemical degradation is caused by the chemical reaction between the PFSA membrane and chemical species such as free radicals. Although chemical degradation of the PFSA membrane has been studied by various experimental techniques, the mechanism of chemical degradation relies much on speculations from ex-situ observations. Recent activities applying theoretical methods such as density functional theory, in situ experimental observation, and mechanistic study by using simplified model compound systems have led to gradual clarification of the atomistic details of the chemical degradation mechanism. In this review paper, we summarize recent reports on the chemical degradation mechanism of the PFSA membrane from an atomistic point of view. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
Open AccessReview Membranes in Lithium Ion Batteries
Membranes 2012, 2(3), 367-383; doi:10.3390/membranes2030367
Received: 30 April 2012 / Revised: 25 June 2012 / Accepted: 27 June 2012 / Published: 4 July 2012
Cited by 34 | PDF Full-text (1735 KB) | HTML Full-text | XML Full-text
Abstract
Lithium ion batteries have proven themselves the main choice of power sources for portable electronics. Besides consumer electronics, lithium ion batteries are also growing in popularity for military, electric vehicle, and aerospace applications. The present review attempts to summarize the knowledge about some
[...] Read more.
Lithium ion batteries have proven themselves the main choice of power sources for portable electronics. Besides consumer electronics, lithium ion batteries are also growing in popularity for military, electric vehicle, and aerospace applications. The present review attempts to summarize the knowledge about some selected membranes in lithium ion batteries. Based on the type of electrolyte used, literature concerning ceramic-glass and polymer solid ion conductors, microporous filter type separators and polymer gel based membranes is reviewed. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
Open AccessReview Membranes for Redox Flow Battery Applications
Membranes 2012, 2(2), 275-306; doi:10.3390/membranes2020275
Received: 8 May 2012 / Revised: 1 June 2012 / Accepted: 7 June 2012 / Published: 19 June 2012
Cited by 63 | PDF Full-text (455 KB) | HTML Full-text | XML Full-text
Abstract
The need for large scale energy storage has become a priority to integrate renewable energy sources into the electricity grid. Redox flow batteries are considered the best option to store electricity from medium to large scale applications. However, the current high cost of
[...] Read more.
The need for large scale energy storage has become a priority to integrate renewable energy sources into the electricity grid. Redox flow batteries are considered the best option to store electricity from medium to large scale applications. However, the current high cost of redox flow batteries impedes the wide spread adoption of this technology. The membrane is a critical component of redox flow batteries as it determines the performance as well as the economic viability of the batteries. The membrane acts as a separator to prevent cross-mixing of the positive and negative electrolytes, while still allowing the transport of ions to complete the circuit during the passage of current. An ideal membrane should have high ionic conductivity, low water intake and excellent chemical and thermal stability as well as good ionic exchange capacity. Developing a low cost, chemically stable membrane for redox flow cell batteries has been a major focus for many groups around the world in recent years. This paper reviews the research work on membranes for redox flow batteries, in particular for the all-vanadium redox flow battery which has received the most attention. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
Open AccessReview Oxygen Selective Membranes for Li-Air (O2) Batteries
Membranes 2012, 2(2), 216-227; doi:10.3390/membranes2020216
Received: 17 April 2012 / Accepted: 7 May 2012 / Published: 11 May 2012
Cited by 16 | PDF Full-text (417 KB) | HTML Full-text | XML Full-text
Abstract
Lithium-air (Li-air) batteries have a much higher theoretical energy density than conventional lithium batteries and other metal air batteries, so they are being developed for applications that require long life. Water vapor from air must be prevented from corroding the lithium (Li) metal
[...] Read more.
Lithium-air (Li-air) batteries have a much higher theoretical energy density than conventional lithium batteries and other metal air batteries, so they are being developed for applications that require long life. Water vapor from air must be prevented from corroding the lithium (Li) metal negative electrode during discharge under ambient conditions, i.e., in humid air. One method of protecting the Li metal from corrosion is to use an oxygen selective membrane (OSM) that allows oxygen into the cell while stopping or slowing the ingress of water vapor. The desired properties and some potential materials for OSMs for Li-air batteries are discussed and the literature is reviewed. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)

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