Preparation and characterization of sulfonated polyimide/TiO2 composite membrane for vanadium redox flow battery

A sulfonated polyimide (SPI)/TiO₂ composite membrane was fabricated by a blend way to improve its performance in vanadium redox flow battery (VRB). Both EDS and XRD results verify the successful preparation of the SPI/TiO₂ composite membrane. The surface SEM image shows its homogeneous structure. TG analysis identifies its thermal stability. The SPI/TiO₂ composite membrane possesses much lower permeability of VO²⁺ ions (2.02?×?10^?7 cm² min^?1) and favorable proton conductivity (3.12?×?10^?2 S cm^?1). The VRB single cell with SPI/TiO₂ composite membrane shows higher coulombic efficiency (93.80–98.00 %) and energy efficiency (83.20–67.61 %) at the current density ranged from 20 to 80 mA cm^?2 compared with that with Nafion 117 membrane. And the operational stability of the as-prepared composite membrane is good after 50 times of cycling tests. Therefore, the low-cost SPI/TiO₂ composite membrane with excellent battery performance exhibits a great potential for application in VRB.     

Chemically modified proton‐conducting membranes based on sulfonated polyimides: Improved water stability and fuel‐cell performance

A series of branched/crosslinked sulfonated polyimide (B/C‐SPI) membranes were prepared and evaluated as proton‐conducting ionomers based on the new concept of in situ crosslinking from sulfonated polyimide (SPI) oligomers and triamine monomers. Chemical branching and crosslinking in SPI oligomers with 1,3,5‐tris(4‐aminophenoxy)benzene as a crosslinker gave the polymer membranes very good water stability and mechanical properties under an accelerated aging treatment in water at 130 °C, despite their high ion‐exchange capacity (2.2–2.6 mequiv g^?1). The resulting polymer electrolytes displayed high proton conductivities of 0.2–0.3 S cm^?1 at 120 °C in water and reasonably high conductivities of 0.02–0.03 S cm^?1 at 50% relative humidity. In a single H₂/O₂ fuel‐cell system at 90 °C, they exhibited high fuel‐cell performances comparable to those of Nafion 112. The B/C‐SPI membranes also displayed good performances in a direct methanol fuel cell with methanol concentrations as high as 50 wt % that were superior to those of Nafion 112. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3751–3762, 2006     

A Bunch‐Like Tertiary Amine Grafted Polysulfone Membrane for VRFBs with Simultaneously High Proton Conductivity and Low Vanadium Ion Permeability

Novel polysulfone membranes with bunch‐like tertiary amine groups are synthesized with high ion selectivity and outstanding chemical stability for vanadium redox flow batteries (VRFBs). The bunch‐like tertiary amine groups simultaneously act as an ionic conductor for proton hopping and vanadium ion transport obstacles. The performance of the membrane is tuned via controlling the grafting degree of the chloromethylated polysulfone. The results show that membranes show increasing proton over vanadium ion (σ/p ) selectivity with increasing functional tertiary groups. VRFBs assembled with the prepared membranes demonstrate an impressive Coulombic efficiency of 98.9% and energy efficiency of 90.9% at a current density of 50 mA cm⁻². Furthermore, the prepared membrane reported in this work shows excellent stability in 1 m VO₂ ⁺ solution at 35 °C over 240 h. Overall, the synthesized polymers provide a new insight into the design of high‐performance membranes toward VRFB applications.

     

Synthesis and Characterization of Sulfonated Polyimides Containing Trifluoromethyl Groups as Proton Exchange Membranes

A novel sulfonated diamine, 4,4′‐bis(4‐amino‐3‐trifluoromethylphenoxy) biphenyl 3,3′‐disulfonic acid (F‐BAPBDS), was successfully synthesized by nucleophilic aromatic substitution of 4,4′‐dihydroxybiphenyl with 2‐chloro‐5‐nitrobenzotrifluoride, followed by reduction and sulfonation. A series of sulfonated polyimides of high molecular weight (SPI‐x, x represents the molar percentage of the sulfonated monomer) were prepared by copolymerization of 1,4,5,8‐naphathlenetetracarboxylic dianhydride (NTDA) with F‐BAPBDS and nonsulfonated diamine. Flexible and tough membranes of high mechanical strength were obtained by solution casting and the electrolyte properties of the polymers were intensively investigated. The copolymer membranes exhibited excellent oxidative stability due to the introducing of the CF₃ groups. The SPI membranes displayed desirable proton conductivity (0.52×10⁻¹–0.97×10⁻¹ S·cm⁻¹) and low methanol permeability (less than 2.8×10⁻⁷ cm²·s⁻¹). The highest proton conductivity (1.89×10⁻¹ S·cm⁻¹) was obtained for the SPI‐90 membrane at 80°C, with an IEC of 2.12 mequiv/g. This value is higher than that of Nafion 117 (1.7×10⁻¹ S·cm⁻¹). Furthermore, the hydrolytic stability of the obtained SPIs is better than the BDSA and ODADS based SPIs due to the hydrophobic CF₃ groups which protect the imide ring from being attacked by water molecules, in spite of its strong electron‐withdrawing behaviors.     

Synthesis and properties of novel sulfonated polyimides containing binaphthyl groups as proton‐exchange membranes for fuel cells

A novel sulfonated diamine monomer, 2,2′‐bis(p‐aminophenoxy)‐1,1′‐binaphthyl‐6,6′‐disulfonic acid (BNDADS), was synthesized. A series of sulfonated polyimide copolymers containing 30–80 mol % BNDADS as a hydrophilic component were prepared. The copolymers showed excellent solubility and good film‐forming capability. Atomic force microscopy phase images clearly showed hydrophilic/hydrophobic microphase separation. The relationship between the proton conductivity and degree of sulfonation was examined. The sulfonated polyimide copolymer with 60 mol % BNDADS showed higher proton conductivity (0.0945–0.161 S/cm) at 20–80 °C in liquid water. The membranes exhibited methanol permeability from 9 × 10^?8 to 5 × 10^?7 cm²/s at 20 °C, which was much lower than that of Nafion (2 × 10^?6cm²/s). The copolymers were thermally stable up to 300 °C. The sulfonated polyimide copolymers with 30–60 mol % BNDADS showed reasonable mechanical strength; for example, the maximum tensile strength at break of the sulfonated polyimide copolymer with 40 mol % BNDADS was 80.6 MPa under high moisture conditions. The optimum concentration of BNDADS was found to be 60 mol % from the viewpoint of proton conductivity, methanol permeability, and membrane stability. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 222–231, 2007     

Enhanced electrochemical properties of a novel polyvinyl formal membrane supporting gel polymer electrolyte by Al2O3 modification

Polyvinyl formal (PVFM)‐based dense polymer membranes with nano‐Al₂O₃ doping are prepared via phase inversion method. The membranes and also their performances as gel polymer electrolytes (GPEs) for lithium ion battery are studied by field emission scanning electron microscope, X‐ray diffraction, differential scanning calorimetry, mechanical strength test, electrolyte uptake test, electrochemical impedance spectroscopy, cyclic voltammetry, and charge–discharge test. The polymer membrane with 3 wt % nano‐Al₂O₃ doping shows the improved mechanical strength of 12.16 MPa and electrolyte uptake of 431.25% compared with 10.47 MPa and 310.59% of the undoped sample, respectively. The membrane absorbs and swells liquid electrolyte to form stable GPE with ionic conductivity of 4.92 × 10^?4 S cm^?1 at room temperature, which is higher than 1.77 × 10^?4 S cm^?1 of GPE from the undoped membrane. Moreover, the Al₂O₃‐modified membrane supporting GPE exhibits wide electrochemical stability window of 1.2–4.8 V (vs. Li/Li⁺) and good compatibility with LiFePO₄ electrode, which implies Al₂O₃‐modified PVFM‐based GPE to be a promising candidate for lithium ion batteries. © 2014 Wiley Periodicals, Inc. J. Polym. Sci. Part B: Polym. Phys. 2014 , 52, 572–577     

Novel sulfonated poly (ether ether ketone)/silica coated carbon nanotubes high‐performance composite membranes for direct methanol fuel cell

The major risk of using carbon nanotubes (CNTs) to modify proton exchange membranes (PEMs) in fuel cells is possible short‐circuiting due to the excellent electrical conductivity of CNTs. In this article, silica‐coated CNTs (SiO₂@CNTs) were successfully prepared by a simple sol–gel process and then used as a new additive in the preparation of sulfonated poly (ether ether ketone) (SPEEK)‐based composite membranes. The insulated and hydrophilic silica coated on the surface of CNTs not only eliminated the risk of short‐circuiting, but also enhanced the interfacial interaction between CNTs and SPEEK, and hence promoted the homogeneous dispersion of CNTs in the SPEEK matrix. Moreover, compared to the methanol permeability of the pure SPEEK membrane (3.42 × 10^?7 cm² s^?1), the SPEEK/SiO₂@CNT composite membrane with a SiO₂@CNT loading of 5 wt% exhibits almost one order of magnitude decrease of methanol crossover, while the proton conductivity still remained above 10^?2 S cm^?1 at room temperature. The obtained results expose the possibility of SPEEK/SiO₂@CNT membranes to be served as high‐performance PEMs in direct methanol fuel cells. Copyright © 2015 John Wiley & Sons, Ltd.     

Combined Intrinsic and Extrinsic Proton Conduction in Robust Covalent Organic Frameworks for Hydrogen Fuel Cell Applications

Developing new materials for the fabrication of proton exchange membranes (PEMs) for fuel cells is of great significance. Herein, a series of highly crystalline, porous, and stable new covalent organic frameworks (COFs) have been developed by a stepwise synthesis strategy. The synthesized COFs exhibit high hydrophilicity and excellent stability in strong acid or base (e.g., 12 m NaOH or HCl) and boiling water. These features make them ideal platforms for proton conduction applications. Upon loading with H₃PO₄, the COFs (H₃PO₄@COFs) realize an ultrahigh proton conductivity of 1.13×10^?1 S cm^?1, the highest among all COF materials, and maintain high proton conductivity across a wide relative humidity (40–100 %) and temperature range (20–80 °C). Furthermore, membrane electrode assemblies were fabricated using H₃PO₄@COFs as the solid electrolyte membrane for proton exchange resulting in a maximum power density of 81 mW cm^?2 and a maximum current density of 456 mA cm^?2, which exceeds all previously reported COF materials.     

Synthesis and properties of novel sulfonated (co)polyimides bearing sulfonated aromatic pendant groups for PEFC applications

Novel sulfonated diamines bearing aromatic pendant groups, namely, 3,5‐diamino‐3′‐sulfo‐4′‐(4‐sulfophenoxy) benzophenone (DASSPB) and 3,5‐diamino‐3′‐sulfo‐4′‐(2,4‐disulfophenoxy) benzophenone (DASDSPB), were successfully synthesized. Novel side‐chain‐type sulfonated (co)polyimides (SPIs) were synthesized from these two diamines, 1,4,5,8‐naphthalene tetracarboxylic dianhydride (NTDA) and nonsulfonated diamines such as 4,4′‐bis(3‐aminophenoxy) phenyl sulfone (BAPPS). Tough and transparent membranes of SPIs with ion exchange capacity of 1.5–2.9 meq g^?1 were prepared. They showed good solubility and high thermal stability up to 300 °C. They showed isotropic membrane swelling in water, which was different from the main‐chain‐type and sulfoalkoxy‐based side‐chain‐type SPIs. The relative humidity (RH) and temperature dependence of proton conductivity were examined. At low RH, the novel SPI membranes showed much higher conductivity than the sulfoalkoxy‐based SPIs. They showed comparable or even higher proton conductivity than Nafion 112 in water at 60 °C (>0.10 S cm^?1). The membrane of NTDA‐DASDSPB/BAPPS (1/1)‐s displayed reasonably high proton conductivities of 0.05 and 0.30 S cm^?1 at 50 and 100% RH, respectively, at 120 °C. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2862–2872, 2006     

Structural modification of chitosan biopolymer as a novel polyelectrolyte membrane for green power generation

In the present study, a series of bioresource polyelectrolytes based on chitosan were synthesized and assessed for applicability in direct methanol fuel cells (DMFCs). A binary cross‐linking agent (sulfosuccinic acid/glutaraldehyde) was used for the structural modification of chitosan and membranes comprising various amounts of sulfosuccinic acid (0, 8, 12, and 16 wt% SSA/wt chitosan) were prepared. It was found that by increasing the sulfonate groups' content up to 16 wt%, proton conductivity and methanol permeability properties reach the values of 0.0452 S cm^?1 and 9.6 × 10^?7 cm² sec^?1, respectively. Based on the membrane selectivity evaluation and activation energy measurements of proton conduction, the optimum composition of cross‐linking agent was determined. The optimum composition resulted in a relatively high proton conductivity of 0.0452 S cm^?1 and a low methanol permeability of 9.6 × 10^?7 cm² sec^?1. Moreover, the optimum proton exchange membrane exhibited selectivity value of 47,100 in comparison with the corresponding value of 40,500 for Nafion® 117. The fabricated membranes showed acceptable oxidative and hydrolytic stability. Furthermore, single cell DMFC performance test revealed a power density of 17 mW cm^?2 at 30°C and 41 mW cm^?2 at 60°C in a 2 M methanol feed. Hence, prepared proton‐conducting bioresource ionomers could have promising potential in the field of green power generation as a low cost and biodegradable polyelectrolyte. Copyright © 2009 John Wiley & Sons, Ltd.     

Alternative proton-conducting electrolytes and their electrochemical performances

This study was focused on the performances of membrane electrode assemblies (MEAs) consisting of the proton–conducting 90PVA/3PWA/4GPTMS/1P₂O₅/2Gl and 80PVA/10PWA/6GPTMS/2P₂O₅/2Gl hybrid membranes as electrolytes together with a Pt/C electrode for proton exchange membrane fuel cells. The MEAs were fabricated and tested as a function of temperature and humidity, and yielded a current density value of about 350?mA?cm^?2 at 60?°C and 100% relative humidity (RH) for the membrane electrolyte 80PVA/10PWA/6GPTMS/2P₂O₅/2Gl. These values were compared with Nafion? membranes, and the single-cell performances based on proton-conducting organic/inorganic hybrid electrolytes were discussed. The test conditions employed were equivalent for each MEA that had an active area of 5?cm². These hybrid membranes showed a high proton conductivity in the range of 10^?3–10^?2 S cm^?1 at low temperatures, i.e., 60, 80, and 90?°C, and 50%, 75%, and 100% RH.     

Synthesis and Characterization of Phenolphthalein‐Containing Sulfonated Poly(arylene ether phosphine oxide)s by Direct Polycondensation for Proton Exchange Membrane

A series of novel phenolphthalein‐containing sulfonated poly(arylene ether phosphine oxide)s (sPAEPP) with various sulfonation degrees were synthesized by direct polycondensation. The structure of sPAEPP was confirmed by ¹H‐NMR, ¹³C‐NMR, and IR spectroscopy. The high‐molecular weight of these polymers was determined by gel permeation chromatography (GPC). The transparent, tough, and flexible membranes could be achieved by solution casting. The macroscopic properties and microstructure of the obtained membranes were investigated in detail. The results showed that these sPAEPP membranes displayed excellent properties in terms of swelling, proton conductivity, and methanol permeability. For example, sPAEPP‐100 membrane exhibited an appropriate water uptake of 33.1%, a swelling ratio of only 11.7% (lower than 20.1% of Nafion 117), a proton conductivity of 0.11 S cm^?1 (similar to that of Nafion 117) at 80 °C, and a methanol permeability of 4.82 × 10^?7 cm² s^?1. Meanwhile, it also presented outstanding oxidative stability. Atomic force microscope (AFM) micrographs showed that the hydrophilic domains of the sPAEPP‐100 membrane formed connected and narrow ionic channels, which contributed to its high proton conductivity and good dimensional stability. As a result, sPAEPP‐100 membrane displays excellent application prospect for fuel cells. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 1097–1104     

Synthesis of sulfonated poly(imidoaryl ether sulfone) membranes for polymer electrolyte membrane fuel cells

New sulfonated poly(imidoaryl ether sulfone) copolymers derived from sulfonated 4,4′‐dichlorodiphenyl sulfone, 4,4′‐dichlorodiphenyl sulfone, and imidoaryl biphenol were evaluated as polymer electrolyte membranes for direct methanol fuel cells. The sulfonated membranes were characterized with Fourier transform infrared spectroscopy, thermogravimetric analysis, and proton nuclear magnetic resonance spectra. The state of water in the membranes was measured with differential scanning calorimetry, and the existence of free water and bound water was discussed in terms of the sulfonation level. The 10 wt % weight loss temperatures of these copolymers were above 470 °C, indicating excellent thermooxidative stability to meet the severe criteria of harsh fuel‐cell conditions. The proton conductivities of the membranes ranged from 3.8 × 10^?2 to 5 × 10^?2 S/cm at 90 °C, depending on the degree of sulfonation. The sulfonated membranes maintained the original proton conductivity even after a boiling water test, and this indicated the excellent hydrolytic stability of the membranes. The methanol permeabilities ranged from 1.65 × 10^?8 to 5.14 × 10^?8 cm²/s and were lower than those of other conventional sulfonated ionomer membranes, particularly commercial perfluorinated sulfonated ionomer (Nafion). The properties of proton and methanol transport were discussed with respect to the state of water in the membranes. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5620–5631, 2005     

Nano oxides incorporated sulfonated poly(ether ether ketone) membranes with improved selectivity and stability for vanadium redox flow battery

Three kinds of sulfonated poly(ether ether ketone) (SPEEK)/nano oxide (Al₂O₃, SiO₂, and TiO₂) composite membranes are fabricated for vanadium redox flow battery (VRFB) application. The composite membranes with 5 wt% of Al₂O₃, SiO₂, and TiO₂ (S/A-5 %, S/S-5 %, and S/T-5 %) exhibit excellent cell performance in VRFB. Incorporation of nano oxides (Al₂O₃, SiO₂, and TiO₂) in SPEEK membrane improves in aspect of thermal, mechanical, and chemical stabilities due to the hydrogen bonds’ interaction between SPEEK matrix and nano oxides. The energy efficiencies (EEs) of composite membranes are higher than that of Nafion 117 membrane, owing to the good balance between proton conductivity and vanadium ion permeability. The discharge–capacity retentions of composite membranes also overwhelm that of Nafion 117 membrane after 200 cycles, indicating their good stability in VRFB system. These low-cost SPEEK/nano oxide composite membranes exhibit great potential for the application in VRFB.     

Custom-made sulfonated poly (vinylidene fluoride-co-hexafluoropropylene) nanocomposite membranes for vanadium redox flow battery applications

Sulfonated poly (vinylidene fluoride-co-hexafluoropropylene) (SPVDF-co-HFP) based nanocomposite proton exchange membranes (PEM) are fabricated by simple solution casting method using polydopamine coated exfoliated molybdenum disulfide (PDA-MoS₂) nanosheets as an alternative for Nafion® in vanadium redox flow batteries (VRFBs). PDA-MoS₂ is synthesized by the etching of exfoliated MoS₂ nanosheets with dopamine molecule by self-polymerization method. Various characteristic results clearly demonstrated that the incorporated PDA-MoS₂ nanosheets homogeneously distributed into the SPVDF-co-HFP matrix and the presence of NH/NH₂ group electrostatically interacts with SPVDF-co-HFP to form a strong acid-base pair and thus enhances the proton transport via Grotthuss type mechanism. Besides, the improvement in surface hydrophilicity provides the vehicle type conduction also. As a result, SPVDF-co-HFP/PM nanocomposite membranes showed higher proton conductivity in comparison with the pristine membrane. Especially SPVDF-co-HFP/PM-1 membrane demonstrated the excellent proton conductivity of 5.24 × 10⁻³ Scm⁻¹ at 25 °C, lower vanadium-ion permeability of 1.05 × 10⁻⁸ cm²min⁻¹ and highest membrane selectivity of 49.9 × 10⁴ Scm⁻³min. On the other hand, vanadium-ion stability of the membrane increased by adding the PD-MoS₂ content is attributed to their strong electrostatic attraction towards the polymer matrix. Overall results suggested that the SPVDF-co-HFP/PM-1 nanocomposite membrane is found to be a better alternative for commercially costly Nafion in VRFB applications.     

Multiblock poly(Phenylene ether nitrile)s with pendant sulfoalkoxyl side chain for H2/air fuel cells at low humidity condition

A series of multiblock poly(phenylene ether nitrile)s with pendant sulfoalkoxyl side chains have been developed as proton exchange membranes for fuel cells. The membranes were obtained by a solution casting method and exhibited good thermal stability, flexibility, and mechanical strength. The membranes displayed well‐developed microphase separation, which largely contributed to their excellent ion conduction ability. One of the new membranes with a low ion exchange capacity of 1.57 mequiv g^?1 showed higher proton conductivity than Nafion 212 over the entire RH range (30–95%). The maximum power output generated in a single cell test reached up to 0.754, 0.640, and 0.414 W cm^?2 at 70 °C under 80%, 50%, and 30% RH conditions, respectively. The current density of the membrane obtained at 0.6 V (I _0.6) was as high as 640 mA cm^?2, which was much higher than that of Nafion 212 (375 mA cm^?2 at 30% RH), suggesting its superiority for a more rapid system start‐up. Furthermore, the in situ durability test at 50% RH was performed at a constant current loading, and the membrane did not show any significant voltage reduction over the 400 h testing period. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 1940–1948     

Proton conductivity and structural properties of precursors mixed PVA/PWA-based hybrid composite membranes

A new class of hybrid nanocomposite membranes containing poly(vinyl alcohol) (PVA), phosphotungstic acid (PWA), 3-glycidyloxypropyltrimethoxysilane (GPTMS), 3-mercaptopropyltrimethoxysilane (MPTMS) and glutaraldehyde (GA) were prepared by a sol–gel method. The aim of this research study was to investigate these novel and highly proton-conducting membranes including their properties, and performances for proton exchange membrane fuel cells (PEMFCs) operating at low temperature. 'Swelling' was observed at room temperature for all the composites. The manner in which the conductivity depended on temperature and humidity was determined and a maximum conductivity value of 2.5?×?10^?2 S cm^?1 was found at a 140°C and 30 % relative humidity (RH) for the PVA/PWA/GPTMS/MPTMS/P₂O₅/GA (50/5/15/10/10/10 wt.%) hybrid composite membrane. It was suggested that the conductivity depended strongly on the nature of the organic/inorganic components as well as on the acid concentration. X-ray diffraction (XRD) results demonstrated that this membrane had an amorphous phase, and Fourier transform infrared spectroscopy (FTIR) results confirmed the composite formation. Finally, membrane-electrode assemblies with a loading of 0.1 mg cm^?2 of Pt/C on a prepared electrode gave rise to a current density of 309 mA cm^?2 at 0.5 V.     

Comparison of Electrochemical Synthesis of Ammonia by Using Sulfonated Polysulfone and Nafion Membrane with Sm1.5Sr0.5NiO4

Polysulfone (PSF) and sulfonated polysulfone (SPSF) were synthesized and characterized by IR spectrum. Sm_1.5Sr_0.5NiO₄ (SSN) and Ni‐Ce_0.8Sm_0.2O_2?δ (Ni‐SDC, Ni‐samarium doped ceria) were prepared and characterized by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). Ammonia was synthesized from wet hydrogen and dry nitrogen with applied voltage, using SSN as cathode, Ni‐SDC as anode, Nafion and SPSF as proton membrane respectively. The performances of Nafion and SPSF membranes in ammonia synthesis were investigated and compared at atmospheric pressure and low temperature (25–100°C). The results demonstrated that the proton conducting performances of Nafion and SPSF membranes were similar and the highest rates of evolution of ammonia were up to 1.05×10^?8 and 1.03×10^?8 mol·cm^?2·s^?1 respectively at 80°C and 2.5 V.     

Enhancing proton conductivity of proton exchange membrane with SPES nanofibers containing porous organic cage

Effective proton conducting sites and establishing proton channels are two critical factors in developing high‐performance proton exchange membranes. This study first establishes a strategy in designing effective proton conducting channels for Nafion by using solution blowing of sulfonated polyethersulfone (SPES) nanofibers containing CC3, which is an emerging porous organic cage that possesses the advantages of dissolvable organic solvents and high proton conduction from its interconnected three‐dimensional pore structure. Our strategy results in SPES nanofiber networks with CC3 uniformly involved in and composite membranes with Nafion‐filled interfiber voids. Benefiting from such structural features, the composite membrane exhibits high proton conductivity (0.315 S cm^?1 at 80°C and 100% RH), low methanol permeability (0.69 × 10^?7 cm² S^?1), excellent water absorption, thermal and dimensional stability, and single‐cell performance. This study provides not only a valuable reference for the application of CC3 but also a new idea for establishment of proton transfer channels.     

Physicochemical properties and mixed electronic and ionic conduction of composite ceramics in the system ZrO<Subscript>2</Subscript>-Bi<Subscript>2</Subscript>CuO<Subscript>4</Subscript>-Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>

Composites ZrO₂-(Bi₂CuO₄+ 20 wt % Bi₂O₃) (50–80 vol % ZrO₂) are synthesized and their physicochemical properties are studied. It is demonstrated that the composites comprise triple-phase mixtures of ZrO₂ of a monoclinic modification, Bi₂CuO₄, and solid solution Bi_2?x Zr _x O_{3 + x/2} and retain their mechanical strength up to 800°C. Impedance spectroscopy is used to examine their electroconductivity at 700–800°C in the interval of partial oxygen pressures extending from 37 to 2.1 × 10⁴ Pa. Contributions made by electronic and ionic constituents to their overall conductivity are evaluated. The best specimens’ conductivity is ～0.01 S cm^?1, with the electronic and ionic transport numbers nearly equal. The composite consisting of 50 vol % ZrO₂ and 50 vol % (Bi₂CuO₄ + 20 wt % Bi₂CuO₄) is tested in the role of an oxygen-separating membrane. The selective flux of oxygen in the temperature interval 750–800°C amounts to (2.2–6.3) × 10^?8 mol cm^?2 s^?1, testifying that these materials may be used as gas-separating membranes.