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Alkaline Fuel Cell
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Suobo Zhang – One of the best experts on this subject based on the ideXlab platform.
a stable anion exchange membrane based on imidazolium salt for Alkaline Fuel CellJournal of Membrane Science, 2014Co-Authors: Yanqi Yang, Jing Wang, Jifu Zheng, Suobo ZhangAbstract:
Abstract A series of poly(arylene ether sulfone) containing bulky imidazole groups (PSf-Im- x ) have been successfully synthesized based on a novel monomer 2,2′-bis-(2-ethyl-4-methyl-imidazole-1-ylmethyl)-biphenyl-4,4′-diol (EMIPO). After quaternized by n-bromobutane, these polymers are evaluated for Alkaline anion exchange membranes (AEMs). The functional group, 2-ethyl-3-butyl-4-methyl-imidazolium, is employed in these new polymers for reason that attaching bulky groups around the imidazolium ring reduces the access of OH − to imidazolium, which enhances the Alkaline stability of the membranes. The membrane with an IEC value of 2.07 possesses ionic (OH − ) conductivity of 0.014 S cm −1 at 30 °C and 80% of the ionic conductivity is maintained after treatment in 1 M KOH at 60 °C for 144 h.
synthesis of multi block poly arylene ether sulfone copolymer membrane with pendant quaternary ammonium groups for Alkaline Fuel CellJournal of Power Sources, 2011Co-Authors: Zhuo Zhao, Junhua Wang, Shenghai Li, Suobo ZhangAbstract:
A series of multi-block poly(arylene ether sulfone)s are synthesized via the copolymerization of bis(4-hydroxyphenol) sulfone, 3,3′, 5,5′-tetramethylbiphenol and 4,4′-difluorodiphenyl sulfone. The resulting multi-block copolymers are brominated by using N-bromosuccinmide (NBS) as bromination reagent. The bromomethylated copolymer is solution cast to form clear, creasable films, and subsequent soaking of these films in aqueous trimethylamine to give benzyltrimethylammonium groups. The anion exchange membranes obtained by the solution hydroxide exchange with aqueous sodium hydroxide show varying degrees of ionic conductivity depending on their ion exchange capacity. The highest hydroxide conductivity 0.029 S cm(-1) is achieved with the QBPES-40 membrane having IEC value of 1.62 mequiv g(-1) at room temperature and 100% RH. The obtained anion exchange membranes also have good mechanical properties and dimensional stability, which greatly facilitates the preparation of a MEA and the Cell operation. (C) 2011 Elsevier B.V. All rights reserved.
novel hydroxide conducting polyelectrolyte composed of an poly arylene ether sulfone containing pendant quaternary guanidinium groups for Alkaline Fuel Cell applicationsMacromolecules, 2010Co-Authors: Junhua Wang, Suobo ZhangAbstract:
Poly(arylene ether sulfone)s were functionalized with quaternary guanidinium groups in order to investigate their properties as novel polymeric hydroxide exchange membrane materials. The quaternized polymers were synthesized via chloromethylation of poly(arylene ether sulfone)s, followed by reactions with pentamethylguanidine. The resulting quaternized polymers PSGCl-x (where x represents the number of the quaternary guanidinium groups/repeat units) presented an elevated molecular weight and exhibited an outstanding solubility in polar aprotic solvents. Consequently flexible and tough membranes of PSGCl-x with varying ionic content could be prepared by casting from the DMSO solution. Novel anion exchange membranes, PSGOH-x, were obtained by an anion exchange of PSGCl-x with 1 M NaOH at room temperature. The membranes displayed a high ionic conductivity and an exCellent chemical stability. The obtained Alkaline anion exchange membranes (AEMs) showed conductivities almost above 10−2 S cm−1 at room temperatu…
Nanwen Li – One of the best experts on this subject based on the ideXlab platform.
quaternized poly 2 6 dimethyl 1 4 phenylene oxide anion exchange membranes based on isomeric benzyltrimethylammonium cations for Alkaline Fuel CellsJournal of Membrane Science, 2020Co-Authors: Chenyang Shao, Rou Chen, Peiwei Zhao, Nanwen LiAbstract:
Abstract Benzyltrimethylammonium (BTMA) is most frequently-used organic cations in anion exchange membrane (AEM) materials. However, BTMA-based AEMs always suffer from low ionic conductivity and insufficient Alkaline stability for practical Alkaline Fuel Cells. Here, we present a systematic investigation of a series of side-chain-type poly (2,6-dimethyl-1,4-phenylene oxide) (PPO) AEMs with constitutional isomerism in BTMA cations. Three isomeric BTMA cations, e.g. meta-BTMA, ortho-BTMA, and para-BTMA, were tethered onto PPO backbones via a flexible spacer using CuAAC reaction, producing side-chain-type AEMs, namely m-QPPO, o-QPPO, and p-QPPO membranes, respectively. As expected, side-chain-type PPO AEMs displayed higher hydroxide conductivity as compared to a control PPO-QA membrane where BTMA cations were directly linked on PPO backbones, due to the microphase-separated morphologies as confirmed by small-angle X-ray scattering (SAXS) results. Although these isomeric quaternized PPO copolymers had identical chemical composition and polymer architectures, they did not share similar properties. Specifically, among three side-chain-type AEMs, the highest hydroxide conductivity of 42.8 mS/cm was observed for m-QPPO membrane having meta-BTMA cations with an ion exchange capacity of 1.93 meq./g at 20 °C, as a result of its high water uptake. In addition to high conductivity, m-QPPO membrane showed superior Alkaline stability with respect to o-QPPO and p-QPPO membranes. After 200 h of aging in 1 M NaOH at 60 °C, 85% of the hydroxide conductivity was retained for m-QPPO AEMs, while more than 30% conductivity loss was observed for o-QPPO and p-QPPO membranes. NMR analysis of the aged membrane suggested that SN2 nucleophilic substitution at benzyl groups is the dominant degradation mechanisms. Furthermore, the AEM Fuel Cells using these PPO AEMs with isomeric BTMA cations were investigated, and the Cell with highly conductive and durable m-QPPO membranes exhibited the best performance with a peak power density of 333 mW/cm2 at a current density of 700 mA/cm2 at 60 °C, comparable to other AEMFCs with PPO-based AEMs. Consequently, this work not only provides a facile and effective strategy to precisely synthesize isomeric AEMs, but also contributes to fundamental insights into the structure-property relationship as well as Alkaline Fuel Cell performance for these isomeric BTMA-based AEMs, which are not explored before.
quaternized poly 2 6 dimethyl 1 4 phenylene oxide anion exchange membranes with pendant sterically protected imidazoliums for Alkaline Fuel CellsJournal of Membrane Science, 2020Co-Authors: Weibing Sheng, Xixing Zhou, Lexuan Wu, Yinghua Shen, Yingda Huang, Nanwen LiAbstract:
Abstract Quaternized poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) copolymers featuring pendant sterically-protected imidazolium groups are presented as new anion exchange membranes (AEMs) for Alkaline Fuel Cell application. Four kinds of imidazoliums, in which the substitutions were located at different positions in imidazolium rings, were grafted on the PPO backbones for systematically assessing structure-property relationship in the resulting imidazolium-based AEMs. Grafting imidazoliums with less substitutions leads to high water uptake as well as sufficient ionic conductivity. The 1,2,4,5-tetramethylimidazolium-functionalized PPO AEM (PPO-TMIm) showed the higher water uptake (53.2 wt%) and hydroxide conductivity (31.7 mS/cm) at room temperature in comparison to the AEM (PPO-TPIm) having sterically-protected 2-(2,4,6-trimethyl)phenyl-4,5-diphenyl-1-methyl- imidazolium. With increasing steric hindrance in the positions of imidazolium rings, PPO-TPIm AEM exhibited superior Alkaline stability. After 192 h of immersion in 1 M NaOH at 80 °C, PPO-TPIm membrane retained 86.7% of the ionic conductivity with no obvious structure change as evidenced by 1H NMR spectroscopy, while dealkylation degradation was observed for AEMs having 1,2,4,5-tetramethylimidazolium and 2-(2,6-dimethyl)phenyl-1-methyl-benzimidazoliums with 16.93% and 19.76% retention of conductivity. Furthermore, these imidazolium-based PPO copolymers were utilized as both polymer electrolyte membranes and ionomers in the membrane electrode assemble for Alkaline Fuel Cell application. A single H2/O2 Fuel Cell testing showed that high peak power density of 128 mA/cm2 at 60 °C was obtained for PPO-TMIm copolymer as an AEM, probably due to its high ion conductivity and comparable Alkaline stability. However, under the same conditions, PPO-TPIm copolymer with the highest Alkaline stability failed to be a separator in Cells, and only 22.1 mW/cm2 of peak power density was achieved as an ionomer in Fuel Cells. These results highlight that both ionic conductivity and Alkaline stability of anion conductive polymers are important for Fuel Cell application as membranes and ionomers.
anion conductive poly 2 6 dimethyl 1 4 phenylene oxide grafted with tailored polystyrene chains for Alkaline Fuel CellsJournal of Membrane Science, 2019Co-Authors: Cheng Yang, Yingda Huang, Junping Dong, Nanwen LiAbstract:
Abstract A series of polystyrene (PS)-grafted poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) having pendent quaternary ammonium groups were synthesized as anion exchange membranes (AEMs) by the “grafting onto” method via a combination of atom transfer radical polymerization (ATRP) and Cu(I)-catalyzed click chemistry. The length of PS grafting chains was controlled readily during ATRP. As expected, the polystyrene grafting chains showed exCellent miscibility with PPO backbone. Therefore, transparent, flexible and tough membranes were obtained by solution casting. The miscible PS grafting chains induced well-defined hydrophobic-hydrophilic separation of the as-obtained PPO AEMs as confirmed by small-angle X-ray scattering (SAXS) technology. Moreover, the hydrophobic grafting chains can effectively control the water absorption, and thus improve the dimensional stability of AEMs in water. The PS-grafted AEMs showed higher IEC-normalized hydroxide conductivity but lower water uptake than the typical AEM without PS side chains, which may be attributed to the well-defined micro-phase separation in AEMs. The highest hydroxide conductivity of 15.9 mS/cm was achieved at 20 °C in spite of its low IEC value of 1.21 meq./g. Alkaline stability testing in 1 M NaOH at 80 °C demonstrated that PS-grafted PPO AEMs with side-chain-type QA cations showed exCellent Alkaline stability as evidenced by the change of hydroxide conductivity and the 1H NMR analysis after 500 h testing. Further H2/O2 Alkaline Fuel Cell using PS-grafted PPO AEMs showed the maximum power density of 64.4 mW/cm2 at a current density of 140 mA/cm2, which is much higher than that of typical AEMs with C-16 alkyl grafting chains.
Tae Hyu Kim – One of the best experts on this subject based on the ideXlab platform.
cardo poly arylene ether sulfone block copolymers with pendant imidazolium side chains as novel anion exchange membranes for direct methanol Alkaline Fuel CellPolymer, 2013Co-Authors: Anil H N Rao, Hyoungjuh Kim, Suk Woo Nam, Tae Hyu KimAbstract:
Abstract A series of phenolphthalein-based cardo poly(arylene ether sulfone) (PES) block copolymers containing pendant imidazolium group (PI-PESs) were synthesized as novel anion exchange membranes for direct methanol Alkaline Fuel Cells. These PI-PESs combine the advantages of pendant anion conductors on the polymer side chains with the thermochemical stabilities of the imidazolium group, showing high hydroxide conductivity, together with good physical and chemical stability under basic conditions. The hydroxide conductivity over 0.03 S/cm at 20 °C and 0.1 S/cm at 80 °C was obtained for the PI-PES membranes. In addition, PI-PES membranes show low permeability to methanol (below 6.74 × 10 −8 cm 2 /s) and very high selectivity (over 3.7 × 10 5 S·s/cm 3 ). These properties make the PI-PESs promising candidate materials for anion exchange membranes for direct methanol Alkaline Fuel Cells.
imidazolium functionalized poly arylene ether sulfone block copolymer as an anion exchange membrane for Alkaline Fuel CellPolymer, 2013Co-Authors: Anil H N Rao, Roshni Lilly Thankamony, Hyoungjuh Kim, Suk Woo Nam, Tae Hyu KimAbstract:
Abstract An ethyl imidazolium-functionalized poly(arylene ether sulfone) (EI-PES) block copolymer was prepared as a novel anion exchange membrane. The EI-PES polymer was synthesized by polycondensation between the F- and OH-terminated oligomers, followed by benzylic bromination and imidazolium functionalization (homogeneous functionalization). The quaternary ammonium-functionalized PES (QA-PES) was also prepared by heterogeneous functionalization, and the properties were compared with EI-PES. The membrane obtained from EI-PES showed a well-defined phase separated morphology between hydrophobic and hydrophilic ionic units of the block copolymer. An IEC of 1.45 meq/g with hydroxide conductivity of 0.03 S/cm at r.t. was observed for EI-PES. The EI-PES membrane also displayed exCellent dimensional, thermal, mechanical and chemical stabilities.