Special Issue "Membranes in Electrochemistry Applications"

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

Deadline for manuscript submissions: closed (31 May 2022) | Viewed by 13429

Special Issue Editor

Dr. Fatemeh Razmjooei
E-Mail
Guest Editor
Institute of Engineering Thermodynamics, German Aerospace Center, HTSP, Pfaffenwaldring 38-40, 70569 Stuttgart, Germany
Interests: membranes for alkaline electrolyzer; AEMs for anion exchange membrane fuel cells and electrolyzers; ion solvating membrane; PEMs for proton exchange membrane fuel cell; PEMs for proton exchange membrane water electrolyzer

Special Issue Information

Dear Colleagues,

Membranes are versatile components, useful for a broad spectrum of electrochemical energy generation and storage systems, which can address the most significant challenges posed by climate change. The main cause of the climate change is attributed to the CO2 emissions as a result of extraction and combustion of fossil fuels, which are the major sources of energy. Therefore, the need for clean, efficient energy sources has brought the attention to the development of renewable energy technologies. Fuel cells (FCs) with the byproduct of heat and water are a highly efficient and environmentally friendly alternative technology for the production of clean energy. Fuel cells can be used in a wide range of applications including stationary power generation, new energy automobiles, portable, and emergency backup power applications. Anion exchange membranes (AEMs) and proton exchange membranes (PEMs) are a critical component of low-temperature fuel cells. However, the benefits of using AEMs in AEM-FCs over PEMs in PEM-FCs include the use of in-expensive non-precious metal-based catalysts, facile reaction kinetics and minimized corrosion effects. However, compared with PEM, AEM has challenges with chemical degradation of ionic groups.

Hydrogen as an alternative clean energy carrier produced by water electrolysis using electricity from renewable power sources is a promising method for storing energy in a large scale. When compared to other available methods, water electrolysis (WE) at low temperature has the advantage of compatibility with all electricity sources and producing high purity hydrogen (>99.9%). Among the low-temperature electrolyzers, anion exchange membrane (AEM) and proton exchange membrane (PEM) electrolyzers are currently available membrane-based technologies for low-temperature water electrolysis. In addition, recently an efficient alkaline electrolyte membrane (such as ion-solvating membranes) as an alternative to the conventional diaphragm for alkaline water electrolysis (AWE) operated in highly concentrated KOH is reported. PEMWE offers several advantages, such as high energy efficiency, a great hydrogen production rate and a compact design, but it is limited by the necessity to use expensive precious-metal-based catalysts. Therefore, the benefits of using AEMs and alkaline electrolyte membranes in AEMWEs and alkaline electrolyzer over PEMs in PEMWEs include the use of non-precious transition metal electrocatalysts and cost competitive stack components such as stainless steel based bipolar plate. Therefore, one of the most critical components of the AEMFCs, AEMWEs and AWE, which has a major influence on cost, efficiency and reliability, is an AEMs and alkaline electrolyte membranes.

Compared to the AEMs and the alkaline electrolyte membranes, the PEMs are at a much higher technology readiness level and more efforts have been made with regard to their developments. However, during the past few years, in parallel to PEM we have been witnessing a growth in membrane research for AEMFC, AEMWE and AWE applications. Materials and fabrication techniques, surface and mechanical properties have been improved and used to synthesis novel membranes. This Special Issue offers a perfect site to provide target values and technical specification for AEMs and alkaline electrolyte membranes, discuss the chemical structures and the various degradation pathways, and also to introduce the state-of-the-art Innovation, technologies and development. It also includes discussion of parallel targets for PEMs, which has achieved good technology readiness level compared to the AEMs and the alkaline electrolyte membranes in both fuel cell and electrolyzers.  This can give the membrane research community an overview over the most prominent and promising AEMs, alkaline electrolyte membranes and PEMs for fuel cell and electrolyzer applications. Authors are therefore kindly invited to submit their latest achievements and results; both original papers and reviews are welcome.

Dr. Fatemeh Razmjooei
Guest Editor

Manuscript Submission Information

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Keywords

  • Anion exchange membrane (AEMs)
  • Proton exchange membrane (PEMs)
  • Ion solvating membrane
  • Alkaline electrolyte membranes
  • Membrane processes
  • Membrane synthesis and modification
  • AEMs for anion exchange membrane water electrolyzer (AEMWE)
  • AEMs for anion exchange membrane fuel cell (AEMFC)
  • PEMs for proton exchange membrane fuel cell (PEMFC)
  • PEMs for proton exchange membrane water electrolyzer (PEMWE)

Published Papers (15 papers)

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Research

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Article
Effect of Clamping Compression on the Mechanical Performance of a Carbon Paper Gas Diffusion Layer in Polymer Electrolyte Membrane Fuel Cells
Membranes 2022, 12(7), 645; https://doi.org/10.3390/membranes12070645 - 23 Jun 2022
Viewed by 234
Abstract
During all the assembly stages of a polymer electrolyte membrane fuel cell (PEMFC) stack, gas diffusion layers (GDLs) endure clamping loads in the through-plane direction several times. Under such complicated assembly conditions, GDLs have to deform with the changes in structure, surface roughness, [...] Read more.
During all the assembly stages of a polymer electrolyte membrane fuel cell (PEMFC) stack, gas diffusion layers (GDLs) endure clamping loads in the through-plane direction several times. Under such complicated assembly conditions, GDLs have to deform with the changes in structure, surface roughness, pore size, etc. A comprehensive understanding of the compressive performance of GDLs at different clamping phases is crucial to the assembly process improvement of PEMFCs. Two typical clamping compression was designed and performed to get close to the actual assembly conditions of PEMFCs. The results indicate that the initial clamping compression and the magnitude of the maximum clamping load have great impacts on the segmented compressive properties of GDLs. The nonlinear compressive performance of the GDL is mainly attributed to the unique microstructural information. The rough surface morphology contributes to the initial compressive characteristics where the big strain along with the small stress occurs, and the irreversible failures such as carbon fiber breakages and adhesive failures between fibers and binders account for the hysteresis between different compression stages. Importantly, it is found that the clamping compression hardly influences the small pore distribution below 175 μm but affects the large pore distribution over 200 μm. Full article
(This article belongs to the Special Issue Membranes in Electrochemistry Applications)
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Article
The Study of Ion Transport Parameters in MC-Based Electrolyte Membranes Using EIS and Their Applications for EDLC Devices
Membranes 2022, 12(2), 139; https://doi.org/10.3390/membranes12020139 - 24 Jan 2022
Cited by 2 | Viewed by 821
Abstract
A solution cast technique was utilized to create a plasticized biopolymer-based electrolyte system. The system was prepared from methylcellulose (MC) polymer as the hosting material and potassium iodide (KI) salt as the ionic source. The electrolyte produced with sufficient conductivity was evaluated in [...] Read more.
A solution cast technique was utilized to create a plasticized biopolymer-based electrolyte system. The system was prepared from methylcellulose (MC) polymer as the hosting material and potassium iodide (KI) salt as the ionic source. The electrolyte produced with sufficient conductivity was evaluated in an electrochemical double-layer capacitor (EDLC). Electrolyte systems’ electrical, structural, and electrochemical properties have been examined using various electrochemical and FTIR spectroscopic techniques. From the electrochemical impedance spectroscopy (EIS), a maximum ionic conductivity of 5.14 × 10−4 S cm−1 for the system with 50% plasticizer was recorded. From the EEC modeling, the ion transport parameters were evaluated. The extent of interaction between the components of the prepared electrolyte was investigated using Fourier transformed infrared spectroscopy (FTIR). For the electrolyte system (MC-KI-glycerol), the tion and electrochemical windows were 0.964 and 2.2 V, respectively. Another electrochemical property of electrolytes is transference number measurement (TNM), in which the ion predominantly responsibility was examined in an attempt to track the transport mechanism. The non-Faradaic nature of charge storing was proved from the absence of a redox peak in the cyclic voltammetry profile (CV). Several decisive parameters have been specified, such as specific capacitance (Cs), coulombic efficiency (η), energy density (Ed), and power density (Pd) at the first cycle, which were 68 F g−1, 67%, 7.88 Wh kg−1, and 1360 Wh kg−1, respectively. Ultimately, during the 400th cycle, the series resistance ESR varied from 70 to 310 ohms. Full article
(This article belongs to the Special Issue Membranes in Electrochemistry Applications)
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Communication
Real-Time Monitoring of HT-PEMFC
Membranes 2022, 12(1), 94; https://doi.org/10.3390/membranes12010094 - 15 Jan 2022
Viewed by 425
Abstract
During the electrochemical reaction of a high temperature proton exchange membrane fuel cell (HT-PEMFC), (in this paper HT-PEMFC means operating in the range of 120 to 200 °C) the inhomogeneity of temperature, flow rate, and pressure in the interior is likely to cause [...] Read more.
During the electrochemical reaction of a high temperature proton exchange membrane fuel cell (HT-PEMFC), (in this paper HT-PEMFC means operating in the range of 120 to 200 °C) the inhomogeneity of temperature, flow rate, and pressure in the interior is likely to cause the reduction of ion conductivity or thermal stability weight loss of proton exchange membrane materials, and it is additionally likely to cause uneven fuel distribution, thereby affecting the working performance and service life of the HT-PEMFC. This study used micro-electro-mechanical systems (MEMS) technology to develop a flexible three-in-one microsensor which is resistant to high temperature electrochemical environments; we selected appropriate materials and process parameters to protect the microsensor from failure or damage under long-term tests. The proposed method can monitor the local temperature, flow rate, and pressure distribution in HT-PEMFC in real time. Full article
(This article belongs to the Special Issue Membranes in Electrochemistry Applications)
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Article
Thermodynamic Modeling and Performance Analysis of Vehicular High-Temperature Proton Exchange Membrane Fuel Cell System
Membranes 2022, 12(1), 72; https://doi.org/10.3390/membranes12010072 - 05 Jan 2022
Viewed by 474
Abstract
Since the high temperature proton exchange membrane fuel cells (HT-PEMFC) stack require a range of auxiliary equipments to maintain operating conditions, it is necessary to consider operation of related components in the design of HT-PEMFC systems. In this paper, a thermodynamic model of [...] Read more.
Since the high temperature proton exchange membrane fuel cells (HT-PEMFC) stack require a range of auxiliary equipments to maintain operating conditions, it is necessary to consider operation of related components in the design of HT-PEMFC systems. In this paper, a thermodynamic model of a vehicular HT-PEMFC system using phosphoric acid doped polybenzimidazole membrane is developed. The power distribution and exergy loss of each component are derived according to thermodynamic analysis, where the stack and heat exchanger are the two components with the greatest exergy loss. In addition, ecological functions and improvement potentials are proposed to evaluate the system performance better. On this basis, the effects of stack inlet temperature, pressure, and stoichiometric on system performance are analyzed. The results showed that the energy efficiency, exergy efficiency and net output power of the system achieved the maximum when the inlet gases temperature is 406.1 K. The system performance is better when the cathode inlet pressure is relatively low and the anode inlet pressure is relatively high. Moreover, the stoichiometry should be reduced to improve the system output performance on the basis of ensuring sufficient gases reaction in the stack. Full article
(This article belongs to the Special Issue Membranes in Electrochemistry Applications)
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Article
Exergetic Performance Coefficient Analysis and Optimization of a High-Temperature Proton Exchange Membrane Fuel Cell
Membranes 2022, 12(1), 70; https://doi.org/10.3390/membranes12010070 - 05 Jan 2022
Viewed by 357
Abstract
Performance of a high-temperature proton exchange membrane fuel cell (HT-PEMFC) and the influence of different parameters on HT-PEMFC is analyzed in this study. Firstly, mathematical expression for energy efficiency, power density, exergy destruction and exergetic performance coefficient (EPC) are derived. Then, [...] Read more.
Performance of a high-temperature proton exchange membrane fuel cell (HT-PEMFC) and the influence of different parameters on HT-PEMFC is analyzed in this study. Firstly, mathematical expression for energy efficiency, power density, exergy destruction and exergetic performance coefficient (EPC) are derived. Then, the relationship between the dimensionless power density, exergy destruction rate, exergetic performance coefficient (EPC) and energy efficiency is compared. Furthermore, the effect of flow rate, doping level, inlet pressure and film thickness are considered to evaluate the performance of HT-PEMFC. Results show that EPC not only considers exergetic loss rate to minimize exergetic loss, but also considers the power density of HT-PEMFC to maximize its power density and improve its efficiency, so EPC represents a better performance criterion. In addition, increasing inlet pressure and doping level can improve EPC and energy efficiency, respectively. Full article
(This article belongs to the Special Issue Membranes in Electrochemistry Applications)
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Article
Dynamic Modeling of a Proton-Exchange Membrane Fuel Cell Using a Gaussian Approach
Membranes 2021, 11(12), 953; https://doi.org/10.3390/membranes11120953 - 01 Dec 2021
Viewed by 883
Abstract
This paper proposes a Gaussian approach for the proton-exchange membrane fuel cell (PEMFC) model that estimates its voltage behavior from the operating current value. A multi-parametric Gaussian model and an unconstrained optimization formulation based on a conventional non-linear least squares optimizer is mainly [...] Read more.
This paper proposes a Gaussian approach for the proton-exchange membrane fuel cell (PEMFC) model that estimates its voltage behavior from the operating current value. A multi-parametric Gaussian model and an unconstrained optimization formulation based on a conventional non-linear least squares optimizer is mainly considered. The model is tested using experimental data from the Ballard Nexa 1.2 kW fuel cell (FC). This methodology offers a promising approach for static and current-voltage, characteristic of the three regions of operation. A statistical study is developed to evaluate the effectiveness and superiority of the proposed FC Gaussian model compared with the Diffusive Global model and the Evolution Strategy. In addition, an approximation to the exponential function for a Gaussian model simplification can be used in systems that require real-time emulators or complex long-time simulations. Full article
(This article belongs to the Special Issue Membranes in Electrochemistry Applications)
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Article
Anion Exchange Membranes Based on Imidazoline Quaternized Polystyrene Copolymers for Fuel Cell Applications
Membranes 2021, 11(11), 901; https://doi.org/10.3390/membranes11110901 - 22 Nov 2021
Cited by 2 | Viewed by 575
Abstract
Imidazoline is a five-membered heterocycle derived by the partial reduction of one double bond of the imidazole ring. This work prepared new anion exchange membranes (AEMs) based on imidazoline quaternized polystyrene copolymers bearing N-b-hydroxyethyl oleyl imidazolinium pendent groups to evaluate the application potential [...] Read more.
Imidazoline is a five-membered heterocycle derived by the partial reduction of one double bond of the imidazole ring. This work prepared new anion exchange membranes (AEMs) based on imidazoline quaternized polystyrene copolymers bearing N-b-hydroxyethyl oleyl imidazolinium pendent groups to evaluate the application potential for anion exchange membrane fuel cells (AEMFCs). For comparison, an imidazole quaternized polystyrene copolymer was also synthesized. The polymer chemical structure was confirmed by FTIR, NMR, and TGA. In addition, the essential properties of membranes, including ion exchange capacity (IEC), water uptake, and hydroxide conductivity, were measured. The alkaline stabilities of imidazolium-based and imidazolinium-based AEMs were compared by means of the changes in the TGA thermograms, FTIR spectra, and hydroxide conductivity during the alkaline treatment in 1 M KOH at 60 °C for 144 h. The results showed that the imidazolinium-based AEMs exhibited relatively lower hydroxide conductivity (5.77 mS/cm at 70 °C) but much better alkaline stability compared with the imidazolium-based AEM. The imidazolinium-based AEM (PSVBImn-50) retained 92% of its hydroxide conductivity after the alkaline treatment. Besides, the fuel cell performance of the imidazolium-based and imidazolinium-based AEMs was examined by single-cell tests. Full article
(This article belongs to the Special Issue Membranes in Electrochemistry Applications)
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Article
Impact of Membrane Phosphoric Acid Doping Level on Transport Phenomena and Performance in High Temperature PEM Fuel Cells
Membranes 2021, 11(11), 817; https://doi.org/10.3390/membranes11110817 - 26 Oct 2021
Cited by 2 | Viewed by 676
Abstract
In this work, a three-dimensional mathematical model including the fluid flow, heat transfer, mass transfer, and charge transfer incorporating electrochemical reactions was developed and applied to investigate the transport phenomena and performance in high-temperature proton exchange membrane fuel cells (HT-PEMFCs) with a membrane [...] Read more.
In this work, a three-dimensional mathematical model including the fluid flow, heat transfer, mass transfer, and charge transfer incorporating electrochemical reactions was developed and applied to investigate the transport phenomena and performance in high-temperature proton exchange membrane fuel cells (HT-PEMFCs) with a membrane phosphoric acid doping level of 5, 7, 9, 11. The cell performance is evaluated and compared in terms of the polarization curve. The distributions of temperature, oxygen mass fraction, water mass fraction, proton conductivity, and local current density of four cases are given and compared in detail. Results show that the overall performance and local transport characteristics are significantly affected by the membrane phosphoric acid doping level. Full article
(This article belongs to the Special Issue Membranes in Electrochemistry Applications)
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Article
Self-Humidifying Membrane for High-Performance Fuel Cells Operating at Harsh Conditions: Heterojunction of Proton and Anion Exchange Membranes Composed of Acceptor-Doped SnP2O7 Composites
Membranes 2021, 11(10), 776; https://doi.org/10.3390/membranes11100776 - 11 Oct 2021
Viewed by 766
Abstract
Here we suggest a simple and novel method for the preparation of a high-performance self-humidifying fuel cell membrane operating at high temperature (>100 °C) and low humidity conditions (<30% RH). A self-humidifying membrane was effectively prepared by laminating together proton and anion exchange [...] Read more.
Here we suggest a simple and novel method for the preparation of a high-performance self-humidifying fuel cell membrane operating at high temperature (>100 °C) and low humidity conditions (<30% RH). A self-humidifying membrane was effectively prepared by laminating together proton and anion exchange membranes composed of acceptor-doped SnP2O7 composites, Sn0.9In0.1H0.1P2O7/Sn0.92Sb0.08(OH)0.08P2O7. At the operating temperature of 100 °C, the electrochemical performances of the membrane electrode assembly (MEA) with this heterojunction membrane at 3.5% RH were better than or comparable to those of each MEA with only the proton or anion exchange membranes at 50% RH or higher. Full article
(This article belongs to the Special Issue Membranes in Electrochemistry Applications)
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Article
Effects of Hydration and Temperature on the Microstructure and Transport Properties of Nafion Polyelectrolyte Membrane: A Molecular Dynamics Simulation
Membranes 2021, 11(9), 695; https://doi.org/10.3390/membranes11090695 - 08 Sep 2021
Cited by 3 | Viewed by 999
Abstract
To investigate the effects of temperature and hydration on the microstructure of polymer electrolyte membrane and the transport of water molecules and hydronium ions, molecular dynamics simulations are performed on Nafion 117 for a series of water contents at different temperatures. The interactions [...] Read more.
To investigate the effects of temperature and hydration on the microstructure of polymer electrolyte membrane and the transport of water molecules and hydronium ions, molecular dynamics simulations are performed on Nafion 117 for a series of water contents at different temperatures. The interactions among the sulfonate groups, hydronium ions, and water molecules are studied according to the analysis of radial distribution functions and coordination numbers. The sizes and connectivity of water clusters are also discussed, and it is found that the hydration level plays a key role in the phase separation of the membrane. However, the effect of the temperature is slight. When the water content increases from 3.5 to 16, the size of water clusters in the membrane increases, and the clusters connect to each other to form continuous channels for diffusion of water molecules and hydronium ions. The diffusion coefficients are estimated by studying the mean square displacements. The results show that the diffusion of water molecules and hydronium ions are both enhanced by the increase of the temperature and hydration level. Furthermore, the diffusion coefficient of water molecules is always much larger than that of hydronium ions. However, the ratio of the diffusion coefficient of water molecules to that of hydronium ions decreases with the increase of water content. Full article
(This article belongs to the Special Issue Membranes in Electrochemistry Applications)
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Article
Performance Analysis and Optimization of a High-Temperature PEMFC Vehicle Based on Particle Swarm Optimization Algorithm
Membranes 2021, 11(9), 691; https://doi.org/10.3390/membranes11090691 - 07 Sep 2021
Cited by 7 | Viewed by 1197
Abstract
In this paper, a high-temperature proton exchange membrane fuel cell (HT-PEMFC) model using the polybenzimidazole membrane doped with phosphoric acid molecules is developed based on finite time thermodynamics, considering various polarization losses and losses caused by leakage current. The mathematical expressions of the [...] Read more.
In this paper, a high-temperature proton exchange membrane fuel cell (HT-PEMFC) model using the polybenzimidazole membrane doped with phosphoric acid molecules is developed based on finite time thermodynamics, considering various polarization losses and losses caused by leakage current. The mathematical expressions of the output power density and efficiency of the HT-PEMFC are deduced. The reliability of the model is verified by the experimental data. The effects of operating parameters and design parameters on the output performance of the HT-PEMFC are further analyzed. The particle swarm optimization (PSO) algorithm is used for the multi-objective optimization of the power density and efficiency of the HT-PEMFC. The results show that the output performance of the optimized HT-PEMFC is improved. Then, according to the different output performance of the low-temperature proton exchange membrane fuel cell (LT-PEMFC), HT-PEMFC, and optimized HT-PEMFC, different design schemes are provided for a fuel cell vehicle (FCV) powertrain. Simulation tests are conducted under different driving cycles, and the results show that the FCV with the optimized HT-PEMFC is more efficient and consumes less hydrogen. Full article
(This article belongs to the Special Issue Membranes in Electrochemistry Applications)
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Article
Flexible 6-in-1 Microsensor for Real-Time Microscopic Monitoring of Proton Battery
Membranes 2021, 11(8), 615; https://doi.org/10.3390/membranes11080615 - 12 Aug 2021
Viewed by 1071
Abstract
According to the comparison between a proton battery and a proton exchange membrane fuel cell (PEMFC), the PEMFC requires oxygen and hydrogen for generating electricity, so a hydrogen tank is required, leading to larger volume of PEMFC. The proton battery can store hydrogen [...] Read more.
According to the comparison between a proton battery and a proton exchange membrane fuel cell (PEMFC), the PEMFC requires oxygen and hydrogen for generating electricity, so a hydrogen tank is required, leading to larger volume of PEMFC. The proton battery can store hydrogen in the carbon layer, combined with the oxygen in the air to form water to generate electricity; thus, the battery cost and the space for a hydrogen tank can be reduced a lot, and it is used more extensively. As the proton battery is a new research area, multiple important physical quantities inside the proton battery should be further understood and monitored so as to enhance the performance of battery. The proton battery has the potential for practical applications, as well as water electrolysis, proton storage and discharge functions, and it can be produced without expensive metals. Therefore, in this study, we use micro-electro-mechanical systems (MEMS) technology to develop a diagnostic tool for the proton battery based on the developed microhydrogen sensor, integrated with the voltage, current, temperature, humidity and flow microsensors developed by this laboratory to complete a flexible integrated 6-in-1 microsensor, which is embedded in the proton battery to measure internal important physical parameters simultaneously so that the reaction condition in the proton battery can be mastered more accurately. In addition, the interaction of physical quantities of the proton battery are discussed so as to enhance the proton battery’s performance. Full article
(This article belongs to the Special Issue Membranes in Electrochemistry Applications)
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Article
Anchoring Water Soluble Phosphotungstic Acid by Hybrid Fillers to Construct Three-Dimensional Proton Transport Networks
Membranes 2021, 11(7), 536; https://doi.org/10.3390/membranes11070536 - 15 Jul 2021
Viewed by 1268
Abstract
Phosphotungstic acid (HPW)-filled composite proton exchange membranes possess high proton conductivity under low relative humidity (RH). However, the leaching of HPW limits their wide application. Herein, we propose a novel approach for anchoring water soluble phosphotungstic acid (HPW) by polydopamine (PDA) coated graphene [...] Read more.
Phosphotungstic acid (HPW)-filled composite proton exchange membranes possess high proton conductivity under low relative humidity (RH). However, the leaching of HPW limits their wide application. Herein, we propose a novel approach for anchoring water soluble phosphotungstic acid (HPW) by polydopamine (PDA) coated graphene oxide and halloysite nanotubes (DGO and DHNTs) in order to construct hybrid three-dimensional proton transport networks in a sulfonated poly(ether ether ketone) (SPEEK) membrane. The introduction of PDA on the surfaces of the hybrid fillers could provide hydroxyl groups and secondary amine groups to anchor HPW, resulting in the uniform dispersion of HPW in the SPEEK matrix. The SPEEK/DGO/DHNTs/HPW (90/5/5/60) composite membrane exhibited higher water uptake and much better conductivity than the SPEEK membrane at low relative humidity. The best conductivity reached wass 0.062 S cm−1 for the composite membrane, which is quite stable during the water immersion test. Full article
(This article belongs to the Special Issue Membranes in Electrochemistry Applications)
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Article
Characteristics of a Plasticized PVA-Based Polymer Electrolyte Membrane and H+ Conductor for an Electrical Double-Layer Capacitor: Structural, Morphological, and Ion Transport Properties
Membranes 2021, 11(4), 296; https://doi.org/10.3390/membranes11040296 - 20 Apr 2021
Cited by 16 | Viewed by 1351
Abstract
Poly (vinyl alcohol) (PVA)-based solid polymer electrolytes doped with ammonium thiocyanate (NH4SCN) and glycerol were fabricated using a solution casting method. Lithium-based energy storage devices are not environmentally friendly materials, and they are toxic. Thus, proton-conducting materials were used in this [...] Read more.
Poly (vinyl alcohol) (PVA)-based solid polymer electrolytes doped with ammonium thiocyanate (NH4SCN) and glycerol were fabricated using a solution casting method. Lithium-based energy storage devices are not environmentally friendly materials, and they are toxic. Thus, proton-conducting materials were used in this work as they are harmless and are smaller than lithium. The interaction between PVA and the electrolyte elements was shown by FTIR analysis. The highest conductivity of 1.82 × 10−5 S cm−1 was obtained by the highest-conducting plasticized system (PSP_2) at room temperature. The mobility, diffusion coefficient, and number density of anions and cations were found to increase with increasing glycerol. FESEM was used to investigate the influence of glycerol on film morphology. TNM showed that the cations and anions were the main charge carriers. LSV showed that the electrochemical stability window of the PSP_2 system was 1.99 V. The PSP_2 system was applied in the preparation of an electrical double layer capacitor device. The shape of the cyclic voltammetry (CV) curve was nearly rectangular with no Faradaic peaks. From the galvanostatic charge-discharge analysis, the power density, energy density, and specific capacitance values were nearly constant beyond the first cycle at 318.73 W/Kg, 2.06 Wh/Kg, and 18.30 F g−1, respectively, for 450 cycles. Full article
(This article belongs to the Special Issue Membranes in Electrochemistry Applications)
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Review

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Review
Modifications on Promoting the Proton Conductivity of Polybenzimidazole-Based Polymer Electrolyte Membranes in Fuel Cells
Membranes 2021, 11(11), 826; https://doi.org/10.3390/membranes11110826 - 27 Oct 2021
Cited by 1 | Viewed by 1050
Abstract
Hydrogen-air proton exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs) are excellent fuel cells with high limits of energy density. However, the low carbon monoxide (CO) tolerance of the Pt electrode catalyst in hydrogen-air PEMFCs and methanol permanent in DMFCs [...] Read more.
Hydrogen-air proton exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs) are excellent fuel cells with high limits of energy density. However, the low carbon monoxide (CO) tolerance of the Pt electrode catalyst in hydrogen-air PEMFCs and methanol permanent in DMFCs greatly hindered their extensive use. Applying polybenzimidazole (PBI) membranes can avoid these problems. The high thermal stability allows PBI membranes to work at elevated temperatures when the CO tolerance can be significantly improved; the excellent methanol resistance also makes it suitable for DMFCs. However, the poor proton conductivity of pristine PBI makes it hard to be directly applied in fuel cells. In the past decades, researchers have made great efforts to promote the proton conductivity of PBI membranes, and various effective modification methods have been proposed. To provide engineers and researchers with a basis to further promote the properties of fuel cells with PBI membranes, this paper reviews critical researches on the modification of PBI membranes in both hydrogen-air PEMFCs and DMFCs aiming at promoting the proton conductivity. The modification methods have been classified and the obtained properties have been included. A guide for designing modifications on PBI membranes for high-performance fuel cells is provided. Full article
(This article belongs to the Special Issue Membranes in Electrochemistry Applications)
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