Phase Separated Methylated Polybenzimidazole (O‐PBI) Based Anion Exchange Membranes

Germer, Wiebke; Leppin, Janine; Kirchner, Carolina Nunes; Cho, Hyeongrae; Kim, Hyoung Juhn; Henkensmeier, Dirk; Lee, Kwan Young; Brela, Mateusz Z.; Michalak, Artur; Dyck, Alexander

doi:10.1002/mame.201400345

Cited by 16 publications

(15 citation statements)

References 58 publications

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“…As known from previous work, the conductivity of hydroxide exchanged alkylated polybenzimidazoles is surprisingly low, because the hydroxide ions are scavenged by the positive carbon atom in position 2 of the imidazolium . In line with this, the hydroxide conductivity of a Blend1 membrane (measured by EIS at 100% rh), was 2.2·× 10 −5 , 1.7·× 10 −5 , and 1.2·× 10 −5 mS/cm at 50, 60, and 70 °C, respectively.…”

Section: Resultssupporting

confidence: 80%

“…For both membranes, the water uptake increases with the anion in the order iodide < carbonate < chloride < bicarbonate. The same order was also observed for methylated O‐PBI membranes . The hydroxide exchanged membranes do not fit well into the trend.…”

Section: Resultssupporting

confidence: 54%

“…For all the systems the trimeric models were considered, with the terminating bonds saturated by hydrogen atoms. The trimers are the smallest models in which the neighbors of the central unit are included, as discussed previously; use of the same models is further justified by comparison of the present results with those obtained for other PBI‐based systems …”

Section: Resultsmentioning

confidence: 58%

“…The explicit solvation was considered by use of 18 water molecules, placed in the vicinity of the anions; i.e., three water molecules interacting with each anion, and reoptimizing the model geometry. Finally, the explicit and implicit solvation (continuum COSMO method) results were combined by use of the cluster‐thermodynamic cycle proposed by Bryantsev et al; the details for the cluster‐thermodynamic cycle applied for PBI‐based systems were presented in our previous work . For consistency with our previous results, the interaction energies and solvation data in the present article are expressed in kcal/mol per cationic site/one anion in polymer; i.e.…”

Section: Methodsmentioning

confidence: 70%

“…To compare the compounds studied in the present work with other PBI‐based systems studied previously, we have performed theoretical calculations with density functional theory (DFT) method. One of the main goals of the theoretical study was to analyze the effect of incorporation of aliphatic chains in the structures of the Me‐PBI on stability of the system.…”

Section: Resultsmentioning

confidence: 99%

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Anion conducting methylated aliphatic PBI and its calculated properties

Cho

Henkensmeier

Brela

et al. 2016

J Polym Sci B Polym Phys

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A methylated polybenzimidazole with an aliphatic chain in the backbone (Me‐PBI‐C10) was synthesized and formed into membranes. Literature suggests that alkyl chains on C2 of imidazolium ions increase their alkaline stability. While this may be true for model compounds or ions attached as a side chain, both our DFT calculations and experimental results show that Me‐PBI‐C10 does not withstand alkaline conditions. To increase the alkaline stability, blend membranes with PBI‐OO were fabricated. A blend membrane with 50% PBI‐OO showed a chloride conductivity of up to 6 mS/cm, indicating that these membranes could find use in non‐alkaline applications like vanadium redox flow batteries (VRFB). The high mechanical stability (tensile strength: 70.25 ± 14.85 MPa, Young modulus: 1.65 ± 0.16 GPa) would be an advantage over currently used Nafion membranes. Finally, three different models were successfully applied to qualitatively predict the water uptake of Me‐PBI‐C10 exchanged with different anions. The results match with experimental data. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 256–265

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Section: Resultssupporting

confidence: 80%

Section: Resultssupporting

confidence: 54%

Section: Resultsmentioning

confidence: 58%

Section: Methodsmentioning

confidence: 70%

Section: Resultsmentioning

confidence: 99%

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Anion conducting methylated aliphatic PBI and its calculated properties

Cho

Henkensmeier

Brela

et al. 2016

J Polym Sci B Polym Phys

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Anion Exchange Ionomers: Impact of Chemistry on Thin‐Film Properties

Luo

Kushner

et al. 2021

Adv Funct Materials

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Ionomer thin‐films (i.e., 20–100 nm) on supports serve as model systems to understand ionomer‐catalyst interfacial behavior as well as the confinement‐driven deviation in properties from bulk membranes. While ionomer thin‐films have been examined for proton exchange ionomers, the thin‐film properties of anion exchange ionomers (AEIs) remain largely unexplored. More importantly, delineating the convoluted impact of chemistry and confinement on thin‐film morphology and hydration is of interest to advancing the field on functional ionic interfaces. In this work, these aspects are studied by using AEIs of different backbones (perfluorinated, aliphatic, and aromatic) and side chains (various lengths, and single versus dual functional groups). Quartz‐crystal microbalance and spectroscopic ellipsometry are used to analyze density and coupled with calculated free volume fraction of thin‐films to provide insights on their gas transport properties. AEI side‐chain's chemical character plays a key role in how confinement modulates hydration (in thin‐film versus bulk). The results elucidate the effects of backbone, side‐chain chemistry versus anion/cation type in the confinement‐driven changes in thin‐film morphology and swelling. This study also provides new insights for tuning AEI transport functionalities at interfaces via chemistry, which can benefit the design and development of electrode‐ionomers for alkaline membrane‐based energy systems.

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Sulfonated Polystyrene/Polybenzimidazole Bilayer Membranes for Vanadium Redox Flow Batteries

Ikhsan,

Abbas,

et al. 2024

Advanced Energy Materials

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Polybenzimidazole has been widely examined as a separator for vanadium redox flow batteries (VRFBs) due to its low vanadium permeability. Its low conductivity can be tackled by combining 1–4 µm thin dense PBI layers with highly conductive mechanically supporting layers, either by lamination or loose stacking. While gel‐PBI is very soft and conductive, the shadow effect of the non‐conductive pore walls of porous supports adds resistance. In this work, these issues are addressed by coating a 25 µm thick highly conductive sulfonated polystyrene layer (S) with a 1 µm thin selective PBI layer (P) to block vanadium crossover. To reduce the number of potential defects, two bilayer membranes can be stacked. A 52 µm thick stack of two membranes (PS–SP, PBI faces the electrodes) shows an area‐specific resistance of 144.8 mΩ cm2 in VO2+‐containing electrolyte and a permeability of 6.85 × 10−14 m2 s−1, both lower than the values for Nafion 212. A VRFB cell test over 3500 charging cycles (1660 h) with an energy efficiency of up to 88.5% at 100 mA cm−2 is shown. Performance losses are reversed by electrolyte rebalancing. With material costs of 1.84 USD m−2, the PSSP(1‐25‐25‐1) membrane promises high performance at low costs.

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Phase Separated Methylated Polybenzimidazole (O‐PBI) Based Anion Exchange Membranes

Cited by 16 publications

References 58 publications

Anion conducting methylated aliphatic PBI and its calculated properties

Anion conducting methylated aliphatic PBI and its calculated properties

Anion Exchange Ionomers: Impact of Chemistry on Thin‐Film Properties

Sulfonated Polystyrene/Polybenzimidazole Bilayer Membranes for Vanadium Redox Flow Batteries

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