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Liquan Chen - One of the best experts on this subject based on the ideXlab platform.
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Nafion organic silica modified tio2 composite Membrane for vanadium redox flow battery via in situ sol gel reactions
Journal of Membrane Science, 2009Co-Authors: Xiangguo Teng, Yongtao Zhao, Xinping Qiu, Liquan ChenAbstract:Abstract To improve the selectivity of Nafion Membrane, reduce the crossover of vanadium ions and decrease water transfer across the Membranes used in VRB systems, the sol–gel method was employed to obtain a composite Membrane of Nafion/organic silica modified TiO 2 (Nafion/Si/Ti hybrid Membrane). The preparation technique and characteristics of the composite Membrane were described. The water transfer and the permeability of vanadium ions were also measured. Results showed that crossover of vanadium ions and water transfer across the Membrane for the composite Membrane have a remarkable decrease comparing with the unmodified Nafion Membrane. It has been confirmed by EDX and FT-IR analysis of the modified Membrane that the Si and Ti elements distributed uniformly in the prepared Membrane. As a result, the coulombic efficiency of the VRB single cell with modified Nafion Membrane was higher than that of the VRB single cell with pristine Nafion Membrane. The ion exchange capacity (IEC), the area resistance and the water uptake of the composite Membrane were also evaluated. Furthermore, the open circuit voltage (OCV) of the VRB with modified and unmodified Nafion Membrane has been carried out and cycle performance of the VRB with modified Membrane proves that it has high stability in strong acid condition.
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Nafion organically modified silicate hybrids Membrane for vanadium redox flow battery
Journal of Power Sources, 2009Co-Authors: Xiangguo Teng, Yongtao Zhao, Xinping Qiu, Liquan ChenAbstract:In our previous work, Nafion/SiO(2) hybrid Membrane was prepared via in situ sol-gel method and used for the vanadium redox flow battery (VRB) system. The VRB with modified Nafion Membrane has shown great advantages over that of the VRB with Nafion Membrane. In this work, a novel Nafion/organically modified silicate (ORMOSIL) hybrids Membrane was prepared via in situ sol-gel reactions for mixtures of tetraethoxysilane (TEOS) and diethoxydimethylsilane (DEDMS). The primary properties of Nafion/ORMOSIL hybrids Membrane were measured and compared with Nafion and Nafion/SiO(2) hybrid Membrane. The permeability of vanadium ions through the Nafion/ORMOSIL hybrids Membrane was measured using an UV-vis spectrophotometer. The results indicate that the hybrids Membrane has a dramatic reduction in crossover of vanadium ions compared with Nafion Membrane. Fourier transform infrared spectra (FT-IR) analysis of the hybrids Membrane reveals that the ORMOSIL phase is well formed within hybrids Membrane. Cell tests identify that the VRB with Nafion/ORMOSIL hybrids Membrane presents a higher coulombic efficiency (CE) and energy efficiency (EE) compared with that of the VRB with Nafion and Nafion/SiO(2) hybrid Membrane. The highest EE of the VRB with Nafion/ORMOSIL hybrids Membrane is 87.4% at 20mA cm(-2). while the EE of VRB with Nafion and the EE of VRB with Nafion/SiO(2) hybrid Membrane are only 73.8% and 79.9% at the same current density. The CE and EE of VRB with Nafion/ORMOSIL hybrids Membrane is nearly no decay after cycling more than 100 times (60mA cm(-2)), which proves the Nafion/ORMOSIL hybrids Membrane possesses high chemical stability during long charge-discharge process under strong acid solutions. The self-discharge rate of the VRB with Nafion/ORMOSIL hybrids Membrane is the slowest among the VRB with Nafion, Nafion/SiO(2) and Nafion/ORMOSIL Membrane,which further proves the excellent vanadium ions blocking characteristic of the prepared hybrids Membrane. (c) 2008 Elsevier B.V. All rights reserved.
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self assembled polyelectrolyte multilayer modified Nafion Membrane with suppressed vanadium ion crossover for vanadium redox flow batteries
Journal of Materials Chemistry, 2008Co-Authors: Jingyu Xi, Xiangguo Teng, Yongtao Zhao, Zenghua Wu, Liquan ChenAbstract:The crossover of vanadium ions through proton-exchange Membranes such as those of Nafion is the chief reason that results in the low energy efficiency and high self-discharge rate of vanadium redox flow batteries (VRB). With respect to applicability, the ideal proton-exchange Membrane used in VRB should possess simultaneously high proton conductivity and low vanadium ion permeability. Here, we report a novel approach using a polyelectrolyte layer-by-layer self-assembly technique to fabricate a barrier layer onto the surface of Nafion Membrane by alternate adsorption of polycation poly(diallyldimethylammonium chloride) (PDDA) and polyanion poly(sodium styrene sulfonate) (PSS), which can suppress the crossover of vanadium ions. The Nafion–[PDDA-PSS]n Membrane (n = the number of multilayers) obtained shows much lower vanadium ion permeability compared with plain Nafion Membrane. Accordingly, the VRB with Nafion–[PDDA-PSS]n Membrane exhibits a higher coulombic efficiency (CE) and energy efficiency (EE) together with a slower self-discharge rate than that of Nafion system. The highest CE of 97.6% and EE of 83.9% can be achieved at charge–discharge current density of 80 mA cm−2 and 20 mA cm−2, respectively.
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self assembled polyelectrolyte multilayer modified Nafion Membrane with suppressed vanadium ion crossover for vanadium redox flow batteries
Journal of Materials Chemistry, 2008Co-Authors: Xiangguo Teng, Yongtao Zhao, Liquan Chen, Xinping QiuAbstract:The crossover of vanadium ions through proton-exchange Membranes such as those of Nafion is the chief reason that results in the low energy efficiency and high self-discharge rate of vanadium redox flow batteries (VRB). With respect to applicability, the ideal proton-exchange Membrane used in VRB should possess simultaneously high proton conductivity and low vanadium ion permeability. Here, we report a novel approach using a polyelectrolyte layer-by-layer self-assembly technique to fabricate a barrier layer onto the surface of Nafion Membrane by alternate adsorption of polycation poly(diallyldimethylammonium chloride) (PDDA) and polyanion poly(sodium styrene sulfonate) (PSS), which can suppress the crossover of vanadium ions. The Nafion–[PDDA-PSS]n Membrane (n = the number of multilayers) obtained shows much lower vanadium ion permeability compared with plain Nafion Membrane. Accordingly, the VRB with Nafion–[PDDA-PSS]n Membrane exhibits a higher coulombic efficiency (CE) and energy efficiency (EE) together with a slower self-discharge rate than that of Nafion system. The highest CE of 97.6% and EE of 83.9% can be achieved at charge–discharge current density of 80 mA cm−2 and 20 mA cm−2, respectively.
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Nafion sio2 hybrid Membrane for vanadium redox flow battery
Journal of Power Sources, 2007Co-Authors: Xinping Qiu, Liquan ChenAbstract:Abstract Sol–gel derived Nafion/SiO2 hybrid Membrane is prepared and employed as the separator for vanadium redox flow battery (VRB) to evaluate the vanadium ions permeability and cell performance. Nafion/SiO2 hybrid Membrane shows nearly the same ion exchange capacity (IEC) and proton conductivity as pristine Nafion 117 Membrane. ICP-AES analysis reveals that Nafion/SiO2 hybrid Membrane exhibits dramatically lower vanadium ions permeability compared with Nafion Membrane. The VRB with Nafion/SiO2 hybrid Membrane presents a higher coulombic and energy efficiencies over the entire range of current densities (10–80 mA cm−2), especially at relative lower current densities (
Xiangguo Teng - One of the best experts on this subject based on the ideXlab platform.
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modification of Nafion Membrane using fluorocarbon surfactant for all vanadium redox flow battery
Journal of Membrane Science, 2015Co-Authors: Xiangguo Teng, Jicui Dai, Geping YinAbstract:Abstract Fluorocarbon surfactant (potassium nonafluoro-1-butanesulfonate) is employed to prepare the Nafion/fluorocarbon (N/FC) Membranes for all vanadium redox flow batteries (VRFB). N/FC Membranes with different FC surfactant mass ratios were successfully prepared by a solution casting method. The addition of FC surfactant has effectively suppressed the vanadium ions permeability and improved the proton conductivity of Nafion. The N/FC Membrane with 5 wt% of FC surfactant (N/FC—5%) exhibits the highest ion selectivity (ratio of proton conductivity to permeability) of 2.0×10 6 S min cm −3 , which is 2.1 times higher than that of pure recast Nafion (r-Nafion) Membrane (9.7×10 5 S min cm −3 ). Consequently, both coulombic efficiency ( CE ) and voltage efficiency ( VE ) of the VRFB with N/FC—5% Membrane are higher than that of the VRFB with r-Nafion Membrane. The average energy efficiency (product of CE and VE ) of the VRFB with N/FC—5% Membrane is 11% higher than that of the VRFB with r-Nafion at current density of 40–80 mA cm −2 .
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solution casting Nafion polytetrafluoroethylene Membrane for vanadium redox flow battery application
Electrochimica Acta, 2013Co-Authors: Xiangguo Teng, Jing Su, Faqiang LiAbstract:Abstract Solution casting method was adopted using Nafion and polytetrafluoroethylene (PTFE) solution to prepare Nafion/PTFE blend Membranes for vanadium redox flow battery application. The physicochemical properties of the Membranes were characterized by using water uptake, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermal analysis (TA). The electrochemical properties of the Membranes were examined by using electrochemical impedance spectroscopy (EIS) and single cell test. Despite the high miscibility of PTFE with Nafion, the addition of hydrophobic PTFE reduces the water uptake, ion exchange capacity ( IEC ) and conductivity of blend Membranes. But PTFE can increase the crystallinity, thermal stability of Nafion/PTFE Membranes and reduce the vanadium permeability. The blend Membrane with PTFE (30 wt%, N 0.7 P 0.3 ) was chosen and investigated for VRB single cell test. The energy efficiency of this VRB with N 0.7 P 0.3 Membrane was 85.1% at current density of 50 mA cm −2 , which was superior to that of recast Nafion (r-Nafion) Membrane (80.5%). Self-discharge test shows that the decay of open circuit potential of N 0.7 P 0.3 Membrane is much lower than that of r-Nafion Membrane. More than 50 cycles charge–discharge test proved that the N 0.7 P 0.3 Membrane possesses high stability in long time running. Chemical stabilities of the chosen N 0.7 P 0.3 Membrane are further proved by soaking the Membrane for 3 weeks in highly oxidative V(V) solution. All results suggest that the addition of PTFE is a simple and effective way to improve the performance of Nafion for VRB application.
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Nafion organic silica modified tio2 composite Membrane for vanadium redox flow battery via in situ sol gel reactions
Journal of Membrane Science, 2009Co-Authors: Xiangguo Teng, Yongtao Zhao, Xinping Qiu, Liquan ChenAbstract:Abstract To improve the selectivity of Nafion Membrane, reduce the crossover of vanadium ions and decrease water transfer across the Membranes used in VRB systems, the sol–gel method was employed to obtain a composite Membrane of Nafion/organic silica modified TiO 2 (Nafion/Si/Ti hybrid Membrane). The preparation technique and characteristics of the composite Membrane were described. The water transfer and the permeability of vanadium ions were also measured. Results showed that crossover of vanadium ions and water transfer across the Membrane for the composite Membrane have a remarkable decrease comparing with the unmodified Nafion Membrane. It has been confirmed by EDX and FT-IR analysis of the modified Membrane that the Si and Ti elements distributed uniformly in the prepared Membrane. As a result, the coulombic efficiency of the VRB single cell with modified Nafion Membrane was higher than that of the VRB single cell with pristine Nafion Membrane. The ion exchange capacity (IEC), the area resistance and the water uptake of the composite Membrane were also evaluated. Furthermore, the open circuit voltage (OCV) of the VRB with modified and unmodified Nafion Membrane has been carried out and cycle performance of the VRB with modified Membrane proves that it has high stability in strong acid condition.
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Nafion organically modified silicate hybrids Membrane for vanadium redox flow battery
Journal of Power Sources, 2009Co-Authors: Xiangguo Teng, Yongtao Zhao, Xinping Qiu, Liquan ChenAbstract:In our previous work, Nafion/SiO(2) hybrid Membrane was prepared via in situ sol-gel method and used for the vanadium redox flow battery (VRB) system. The VRB with modified Nafion Membrane has shown great advantages over that of the VRB with Nafion Membrane. In this work, a novel Nafion/organically modified silicate (ORMOSIL) hybrids Membrane was prepared via in situ sol-gel reactions for mixtures of tetraethoxysilane (TEOS) and diethoxydimethylsilane (DEDMS). The primary properties of Nafion/ORMOSIL hybrids Membrane were measured and compared with Nafion and Nafion/SiO(2) hybrid Membrane. The permeability of vanadium ions through the Nafion/ORMOSIL hybrids Membrane was measured using an UV-vis spectrophotometer. The results indicate that the hybrids Membrane has a dramatic reduction in crossover of vanadium ions compared with Nafion Membrane. Fourier transform infrared spectra (FT-IR) analysis of the hybrids Membrane reveals that the ORMOSIL phase is well formed within hybrids Membrane. Cell tests identify that the VRB with Nafion/ORMOSIL hybrids Membrane presents a higher coulombic efficiency (CE) and energy efficiency (EE) compared with that of the VRB with Nafion and Nafion/SiO(2) hybrid Membrane. The highest EE of the VRB with Nafion/ORMOSIL hybrids Membrane is 87.4% at 20mA cm(-2). while the EE of VRB with Nafion and the EE of VRB with Nafion/SiO(2) hybrid Membrane are only 73.8% and 79.9% at the same current density. The CE and EE of VRB with Nafion/ORMOSIL hybrids Membrane is nearly no decay after cycling more than 100 times (60mA cm(-2)), which proves the Nafion/ORMOSIL hybrids Membrane possesses high chemical stability during long charge-discharge process under strong acid solutions. The self-discharge rate of the VRB with Nafion/ORMOSIL hybrids Membrane is the slowest among the VRB with Nafion, Nafion/SiO(2) and Nafion/ORMOSIL Membrane,which further proves the excellent vanadium ions blocking characteristic of the prepared hybrids Membrane. (c) 2008 Elsevier B.V. All rights reserved.
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self assembled polyelectrolyte multilayer modified Nafion Membrane with suppressed vanadium ion crossover for vanadium redox flow batteries
Journal of Materials Chemistry, 2008Co-Authors: Jingyu Xi, Xiangguo Teng, Yongtao Zhao, Zenghua Wu, Liquan ChenAbstract:The crossover of vanadium ions through proton-exchange Membranes such as those of Nafion is the chief reason that results in the low energy efficiency and high self-discharge rate of vanadium redox flow batteries (VRB). With respect to applicability, the ideal proton-exchange Membrane used in VRB should possess simultaneously high proton conductivity and low vanadium ion permeability. Here, we report a novel approach using a polyelectrolyte layer-by-layer self-assembly technique to fabricate a barrier layer onto the surface of Nafion Membrane by alternate adsorption of polycation poly(diallyldimethylammonium chloride) (PDDA) and polyanion poly(sodium styrene sulfonate) (PSS), which can suppress the crossover of vanadium ions. The Nafion–[PDDA-PSS]n Membrane (n = the number of multilayers) obtained shows much lower vanadium ion permeability compared with plain Nafion Membrane. Accordingly, the VRB with Nafion–[PDDA-PSS]n Membrane exhibits a higher coulombic efficiency (CE) and energy efficiency (EE) together with a slower self-discharge rate than that of Nafion system. The highest CE of 97.6% and EE of 83.9% can be achieved at charge–discharge current density of 80 mA cm−2 and 20 mA cm−2, respectively.
Weiwei Cai - One of the best experts on this subject based on the ideXlab platform.
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an enhanced proton conductivity and reduced methanol permeability composite Membrane prepared by sulfonated covalent organic nanosheets Nafion
International Journal of Hydrogen Energy, 2019Co-Authors: Jin Yao, Ziming Zhao, Jing Guo, Suobo Zhang, Weiwei CaiAbstract:Abstract Sulfonated covalent organic nanosheets (SCONs) with a functional group (−SO3H) are effective at reducing ion channels length and facilitating proton diffusion, indicating the potential advantage of SCONs in application for proton exchange Membranes (PEMs). In this study, Nafion-SCONs composite Membranes were prepared by introducing SCONs into a Nafion Membrane. The incorporation of SCONs not only improved proton conductivity, but also suppressed methanol permeability. This was due to the even distribution of ion channels, formed by strong electrostatic interaction between the well dispersed SCONs and Nafion polymer molecules. Notably, Nafion-SCONs-0.6 was the best choice of composite Membranes. It exhibited enhanced performance, such as high conductivity and low methanol permeability. The direct methanol fuel cell (DMFC) with Nafion-SCONs-0.6 Membrane also showed higher power density (118.2 mW cm−2), which was 44% higher than the cell comprised of Nafion Membrane (81.9 mW cm−2) in 2 M methanol at 60 °C. These results enabled us to work on building composite Membranes with enhanced properties, made from nanomaterials and polymer molecules.
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effect of nano size of functionalized silica on overall performance of swelling filling modified Nafion Membrane for direct methanol fuel cell application
Applied Energy, 2018Co-Authors: Xingying Luo, Jie Xiong, Zhao Liu, Weiwei CaiAbstract:Abstract A non-destructive swelling-filling (SF) strategy is applied for inorganic modification on Nafion by using functionalized silica (F-silica) nanoparticles as fillers. With the facilely prepared F-silica gel as SF treating agent, the mono-dispersed F-silica nanoparticles can in-situ insert into the Nafion Membrane and tightly anchor on the Nafion chains through the hydrogen bonding interaction between the oxygen containing groups on F-silica fillers and –SO3H group on Nafion chains. The F-silica nanoparticles act as bi-functional fillers in the modified Nafion Membrane to improve proton conductive and methanol-permeation resistive performances simultaneously. 100% enhanced proton/methanol selectivity therefore leads to a more than 30% improved direct methanol fuel cell (DMFC) performance in terms of power output. By considering the great mechanical, thermal and oxidative stabilities comprehensively, the F-silica-Nafion Membranes exhibit promising application potential for high-energy DMFC application.
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an in situ nano scale swelling filling strategy to improve overall performance of Nafion Membrane for direct methanol fuel cell application
Journal of Power Sources, 2016Co-Authors: Kun Fan, Weiwei Cai, Hansong ChengAbstract:Abstract A novel in-situ nano-scale swelling-filling (SF) strategy is proposed to modify commercial Nafion Membranes for performance enhancement of direct methanol fuel cells (DMFCs). A Nafion Membrane was filled in -situ with proton conductive macromolecules (PCMs) in the swelling process of a Nafion Membrane in a PCM solution. As a result, both proton conductivity and methanol-permeation resistivity of the SF-treated Naifion Membrane was substantially improved with the selectivity nearly doubled compared to the original Nafion Membrane. The mechanical strength of the optimal SF treated Nafion Membrane was also enforced due to the strong interaction between the PCM fillers and the Nafion molecular chains. As a result, a DMFC equipped with the SF-treated Membrane yielded a 33% higher maximum power density than that offered by the DMFC with the original Nafion Membrane.
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a bi functional polymeric nano sieve Nafion composite Membrane improved performance for direct methanol fuel cell applications
International Journal of Hydrogen Energy, 2016Co-Authors: Weiwei Cai, Kun Fan, Jing Li, Guoxiao Xu, Sen Xu, Hansong ChengAbstract:Abstract A polyamide macromolecular proton conductor with COOH end-capped is used as a bi-functional polymeric nano-sieve (BFPS) in composite Nafion Membranes to simultaneously improve the proton conductivity and suppress the methanol permeation. With 1%–5% incorporation of the BFPS into the composite Nafion Membrane, not only the proton conductivity and the methanol-permeation resistivity are improved, but also stronger mechanical strength is obtained, compared to the pure Nafion Membrane. We show that the Membrane with a 5% BFPS content gives the optimal performance and the composite Membrane is well suited for applications in direct methanol fuel cells (DMFCs). The DMFC performance of the Membrane is found to be more than 60% better than the performance of a recast pure Nafion Membrane.
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a modified Nafion Membrane with extremely low methanol permeability via surface coating of sulfonated organic silica
Chemical Communications, 2012Co-Authors: Yuwei Zhang, Weiwei Cai, Liang Liang, Changpeng Liu, Wei XingAbstract:We developed a method to significantly decrease the methanol permeability of a Nafion Membrane that does not require sacrificing its proton conductivity and mechanical stability. The Nafion Membrane modified by the coating of a thin layer of sulfonated organic silica on the Membrane surface exhibits significantly decreased methanol permeability--the permeability is decreased to an undetectable level--while retaining an acceptable ionic conductivity of 0.029 S cm(-1).
Xinping Qiu - One of the best experts on this subject based on the ideXlab platform.
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insights into the impact of the Nafion Membrane pretreatment process on vanadium flow battery performance
ACS Applied Materials & Interfaces, 2016Co-Authors: Bo Jiang, Le Liu, Xinping QiuAbstract:Nafion Membranes are now the most widely used Membranes for long-life vanadium flow batteries (VFBs) because of their extremely high chemical stability. Today, the type of Nafion Membrane that should be selected and how to pretreat these Nafion Membranes have become critical issues, which directly affects the performance and cost of VFBs. In this work, we chose the Nafion 115 Membrane to investigate the effect of the pretreatment process (as received, wet, boiled, and boiled and dried) on the performance of VFBs. The relationship between the nanostructure and transport properties of Nafion 115 Membranes is elucidated by wide-angle X-ray diffraction and small-angle X-ray scattering techniques. The self-discharge process, battery efficiencies, electrolyte utilization, and long-term cycling stability of VFBs with differently pretreated Nafion Membranes are presented comprehensively. An online monitoring system is used to monitor the electrolyte volume that varies during the long-term charge–discharge test of...
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Nafion organic silica modified tio2 composite Membrane for vanadium redox flow battery via in situ sol gel reactions
Journal of Membrane Science, 2009Co-Authors: Xiangguo Teng, Yongtao Zhao, Xinping Qiu, Liquan ChenAbstract:Abstract To improve the selectivity of Nafion Membrane, reduce the crossover of vanadium ions and decrease water transfer across the Membranes used in VRB systems, the sol–gel method was employed to obtain a composite Membrane of Nafion/organic silica modified TiO 2 (Nafion/Si/Ti hybrid Membrane). The preparation technique and characteristics of the composite Membrane were described. The water transfer and the permeability of vanadium ions were also measured. Results showed that crossover of vanadium ions and water transfer across the Membrane for the composite Membrane have a remarkable decrease comparing with the unmodified Nafion Membrane. It has been confirmed by EDX and FT-IR analysis of the modified Membrane that the Si and Ti elements distributed uniformly in the prepared Membrane. As a result, the coulombic efficiency of the VRB single cell with modified Nafion Membrane was higher than that of the VRB single cell with pristine Nafion Membrane. The ion exchange capacity (IEC), the area resistance and the water uptake of the composite Membrane were also evaluated. Furthermore, the open circuit voltage (OCV) of the VRB with modified and unmodified Nafion Membrane has been carried out and cycle performance of the VRB with modified Membrane proves that it has high stability in strong acid condition.
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Nafion organically modified silicate hybrids Membrane for vanadium redox flow battery
Journal of Power Sources, 2009Co-Authors: Xiangguo Teng, Yongtao Zhao, Xinping Qiu, Liquan ChenAbstract:In our previous work, Nafion/SiO(2) hybrid Membrane was prepared via in situ sol-gel method and used for the vanadium redox flow battery (VRB) system. The VRB with modified Nafion Membrane has shown great advantages over that of the VRB with Nafion Membrane. In this work, a novel Nafion/organically modified silicate (ORMOSIL) hybrids Membrane was prepared via in situ sol-gel reactions for mixtures of tetraethoxysilane (TEOS) and diethoxydimethylsilane (DEDMS). The primary properties of Nafion/ORMOSIL hybrids Membrane were measured and compared with Nafion and Nafion/SiO(2) hybrid Membrane. The permeability of vanadium ions through the Nafion/ORMOSIL hybrids Membrane was measured using an UV-vis spectrophotometer. The results indicate that the hybrids Membrane has a dramatic reduction in crossover of vanadium ions compared with Nafion Membrane. Fourier transform infrared spectra (FT-IR) analysis of the hybrids Membrane reveals that the ORMOSIL phase is well formed within hybrids Membrane. Cell tests identify that the VRB with Nafion/ORMOSIL hybrids Membrane presents a higher coulombic efficiency (CE) and energy efficiency (EE) compared with that of the VRB with Nafion and Nafion/SiO(2) hybrid Membrane. The highest EE of the VRB with Nafion/ORMOSIL hybrids Membrane is 87.4% at 20mA cm(-2). while the EE of VRB with Nafion and the EE of VRB with Nafion/SiO(2) hybrid Membrane are only 73.8% and 79.9% at the same current density. The CE and EE of VRB with Nafion/ORMOSIL hybrids Membrane is nearly no decay after cycling more than 100 times (60mA cm(-2)), which proves the Nafion/ORMOSIL hybrids Membrane possesses high chemical stability during long charge-discharge process under strong acid solutions. The self-discharge rate of the VRB with Nafion/ORMOSIL hybrids Membrane is the slowest among the VRB with Nafion, Nafion/SiO(2) and Nafion/ORMOSIL Membrane,which further proves the excellent vanadium ions blocking characteristic of the prepared hybrids Membrane. (c) 2008 Elsevier B.V. All rights reserved.
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self assembled polyelectrolyte multilayer modified Nafion Membrane with suppressed vanadium ion crossover for vanadium redox flow batteries
Journal of Materials Chemistry, 2008Co-Authors: Xiangguo Teng, Yongtao Zhao, Liquan Chen, Xinping QiuAbstract:The crossover of vanadium ions through proton-exchange Membranes such as those of Nafion is the chief reason that results in the low energy efficiency and high self-discharge rate of vanadium redox flow batteries (VRB). With respect to applicability, the ideal proton-exchange Membrane used in VRB should possess simultaneously high proton conductivity and low vanadium ion permeability. Here, we report a novel approach using a polyelectrolyte layer-by-layer self-assembly technique to fabricate a barrier layer onto the surface of Nafion Membrane by alternate adsorption of polycation poly(diallyldimethylammonium chloride) (PDDA) and polyanion poly(sodium styrene sulfonate) (PSS), which can suppress the crossover of vanadium ions. The Nafion–[PDDA-PSS]n Membrane (n = the number of multilayers) obtained shows much lower vanadium ion permeability compared with plain Nafion Membrane. Accordingly, the VRB with Nafion–[PDDA-PSS]n Membrane exhibits a higher coulombic efficiency (CE) and energy efficiency (EE) together with a slower self-discharge rate than that of Nafion system. The highest CE of 97.6% and EE of 83.9% can be achieved at charge–discharge current density of 80 mA cm−2 and 20 mA cm−2, respectively.
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Nafion sio2 hybrid Membrane for vanadium redox flow battery
Journal of Power Sources, 2007Co-Authors: Xinping Qiu, Liquan ChenAbstract:Abstract Sol–gel derived Nafion/SiO2 hybrid Membrane is prepared and employed as the separator for vanadium redox flow battery (VRB) to evaluate the vanadium ions permeability and cell performance. Nafion/SiO2 hybrid Membrane shows nearly the same ion exchange capacity (IEC) and proton conductivity as pristine Nafion 117 Membrane. ICP-AES analysis reveals that Nafion/SiO2 hybrid Membrane exhibits dramatically lower vanadium ions permeability compared with Nafion Membrane. The VRB with Nafion/SiO2 hybrid Membrane presents a higher coulombic and energy efficiencies over the entire range of current densities (10–80 mA cm−2), especially at relative lower current densities (
Zhigang Shao - One of the best experts on this subject based on the ideXlab platform.
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development of proton conducting Membrane based on incorporating a proton conductor 1 2 4 triazolium methanesulfonate into the Nafion Membrane
Journal of Energy Chemistry, 2015Co-Authors: Yongyi Jiang, Jinkai Hao, Jiangshui Luo, Zhigang ShaoAbstract:In this paper, 1,2,4-triazolium methanesulfonate (C2H4N+3CH3SO−3, [Tri][MS]), an ionic conductor, was successfully synthesized. It exhibited high ionic conductivity of 18.60 mS·cm−1 at 140°C and reached up to 36.51 mS·cm−1 at 190°C. [Tri][MS] was first applied to modify Nafion Membrane to fabricate [Tri][MS]/Nafion Membrane by impregnation method at 150°C. The prepared composite Membrane showed high thermal stability with decomposed temperature above 200°C in air atmosphere. In addition, the Membrane indicated good ionic conductivity with 3.67 mS·cm−1 at 140°C and reached up to 13.23 mS·cm−1 at 180°C. The structure of the [Tri][MS] and the composite Membrane were characterized by FTIR and the compatibility of [Tri][MS] and Pt/C catalyst was studied by a cyclic voltammetry (CV) method. Besides, the [Tri][MS]/Nafion Membrane (thickness of 65 µm) was evaluated with single fuel cell at high temperature and without humidification. The highest power density of [Tri][MS]/Nafion Membrane was 3.20 mW·cm-2 at 140°C and 4.90 mW·cm-2 at 150°C, which was much higher than that of Nafion Membrane.
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hybrid Nafion inorganic oxides Membrane doped with heteropolyacids for high temperature operation of proton exchange Membrane fuel cell
Solid State Ionics, 2006Co-Authors: Zhigang Shao, I-ming HsingAbstract:Performance of the proton exchange Membrane fuel cell (PEMFC) with composite Nafion-inorganic additives such as silicon oxide (SiO2), titanium dioxide (TiO2), tungsten oxide (WO3), and SiO2/phosphotungstic acid (PWA) has been studied for the operation of temperature of above 100 degrees C. These composite Membranes are prepared by the way of blending of the inorganic oxides with Nafion solution by the recasting procedure. The physico-chemical properties studied by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques have proved the uniform and homogeneous distribution of these oxides and the consequent enhancement of crystalline character of these Membranes. The thermogravimetry analysis (TGA) results have indicated that the additives TiO2 and WO3 have accelerated decomposition of the Membrane at an earlier temperature than that of the Nafion Membrane. The modified Membranes have shown higher uptake of water relative to that of the unmodified Membranes. The proton conductivity of the modified Membranes, except that of the Nafion/TiO2, is found to be close to that of the native Nafion Membrane at high temperature and at 100% relative humidity (RH), however, it was much higher at low RH. The performance of these modified Membranes in the PEMFC operated at 110 degrees C and 70% RH is better than that of Nafion Membrane and is found in the order of Nafion/SiO2/PkVA > Nafion/SiO2 > Nafion/WO3 > Nafion/TiO2. (c) 2006 Elsevier B.V. All rights reserved.
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Carbon nanotubes reinforced Nafion composite Membrane for fuel cell applications
Electrochemical and Solid-State Letters, 2006Co-Authors: Yong-hao Liu, Zhigang Shao, Danmin Xing, Huamin ZhangAbstract:A carbon nanotubes (CNTs) reinforced Nafion composite Membrane for the H-2/O-2 fuel cell was developed. CNTs/Nafion composite Membrane, in which CNTs were dispersed uniformly, was prepared by solution-casting. CNTs reinforced Membranes, with the addition of a small amount of CNTs (1 wt %), showed excellent mechanical strength. The CNTs/Nafion composite Membrane could also decrease dimensional change compared with the commercial Nafion Membrane. The performance of the CNTs reinforced composite Membrane (50 mu m) was almost the same as the cell prepared with commercial Nafion NRE-212 Membrane. (c) 2006 The Electrochemical Society.
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preparation and characterization of hybrid Nafion silica Membrane doped with phosphotungstic acid for high temperature operation of proton exchange Membrane fuel cells
Journal of Membrane Science, 2004Co-Authors: Zhigang Shao, Prabhuram Joghee, I-ming HsingAbstract:Nafion/silicon oxide (SiO2)/phosphotungstic acid (PWA) and Nafion/silicon oxide composite Membranes were studied for the H2/O2 proton exchange Membrane fuel cells (PEMFCs) operated above 100 °C. The composite Membranes were prepared by the recasting procedure, using Nafion solution mixed with SiO2 and PWA/SiO2 mixtures. The physico-chemical properties of these recast composite Membranes were studied by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, thermogravimetry-DTA (TG-DTA) and Fourier transform infrared (FTIR) spectroscopy. These results showed that SiO2 and PWA are compatible with the Nafion Membrane. Furthermore, the incorporation of the SiO2 and PWA into the Nafion Membrane could increase the crystallinity of the Nafion recast Membrane and also improve the initial degradation temperature of the Nafion Membrane. It was found that the composite Membrane showed a higher uptake of water compared with the Nafion recast Membrane. The proton conductivity of the composite Membranes appeared to be similar to that of the native Nafion Membrane at high temperatures and at 100% relative humidity (RH), however, it was much higher at low RH. When the composite Membranes viz. Nafion/SiO2/PWA and Nafion/SiO2 were employed as an electrolyte in H2/O2 PEMFC, the higher current density values (540 and 320 mA/cm2 at 0.4 V, respectively) were obtained than that of the Nafion 115 Membrane (95 mA/cm2), under the operating condition of 110 °C and at the humidified temperature of 100 °C.
