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. 相似文献
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.
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. 相似文献
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. 相似文献
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. 相似文献
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. 相似文献
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. 相似文献
Polysulfone (PSF) and sulfonated polysulfone (SPSF) were synthesized and characterized by IR spectrum. Sm1.5Sr0.5NiO4 (SSN) and Ni‐Ce0.8Sm0.2O2?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. 相似文献
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. 相似文献
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. 相似文献