Amino‐Functional Polybenzimidazole Blends with Enhanced Phosphoric Acid Mediated Proton Conductivity as Fuel Cell Electrolytes

Aili, David; Javakhishvili, Irakli; Han, Junyoung; Jankova, Katja; Pan, Chao; Hvilsted, Søren; Jensen, Jens Oluf; Bjerrum, Niels; Li, Qingfeng

doi:10.1002/macp.201600059

Cited by 15 publications

(10 citation statements)

References 54 publications

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“…The proton conductivity of the membrane based on linear PBI was slightly above 0.1 S cm −1 at 160 °C, in consistence with data in literature for membranes of similar phosphoric acid contents , . The acid content of the PBI‐CLIII was comparable to that of the linear PBI membrane and thus the conductivity was similar.…”

Section: Resultssupporting

confidence: 86%

Fuel Cell Electrolytes of Polybenzimidazole Membranes Cross‐linked with Bis(chloromethyl) Arenes

et al. 2018

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Cross‐linking of phosphoric acid doped polybenzimidazole membranes as fuel cell electrolytes represents an attractive approach to improving the mechanical robustness at a high acid loading. Numerous cross‐linking concepts have been reported in the literature, but a deeper understanding of how the cross‐linking chemistry affects the physicochemical properties of the membrane and its fuel cell performance and durability remains to be assessed. In this work, a series of cross‐linked membranes are prepared using cross‐linking agents of different regio‐chemistry and steric nature. It is shown, that the nature of the cross‐linking agent has a large impact on the effective degree of cross‐linking, which in turn determines the acid doping characteristics and ultimately the fuel cell performance and acid retention during long‐term operation.

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Section: Resultssupporting

confidence: 86%

Fuel Cell Electrolytes of Polybenzimidazole Membranes Cross‐linked with Bis(chloromethyl) Arenes

et al. 2018

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“…The polarization curves for the cells with different thicknesses of the middle layer are shown in Figure 2a. Both cells showed an almost linear slope, which suggests an ohmic-dominant process throughout the whole current density range [27,28]. Potentiostatic impedance scans of the working cell further showed a very small arc representing the hydrogen oxidation and reduction at the anode and cathode, respectively.…”

Section: Resultsmentioning

confidence: 89%

“…A schematic diagram of the membrane electrode assembly (MEA) is shown in Figure 1. The PBI membranes were prepared by solution casting from N,N-dimethylacteamide (DMAc), using from poly(2,2´-(m-phenylene)-5,5´-bibenzimidazole) with an inherent viscosity of 1.44 dL g -1 (500 mg dL -1 in 96% H 2 SO 4 at 30.0 °C) as prepared according to protocols reported in the literature [27]. After extensive washing in demineralized water, the PBI membranes were…”

Section: Methodsmentioning

confidence: 99%

Probing phosphoric acid redistribution and anion migration in polybenzimidazole membranes

Becker

Cleemann

Aili

et al. 2017

Electrochemistry Communications

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Q. (2017). Probing phosphoric acid redistribution and anion migration in polybenzimidazole membranes. Electrochemistry Communications, 82, 21-24. AbstractMicro platinum electrodes embedded in a laminated phosphoric acid doped polybenzimidazole membrane are employed to monitor the acid migration during hydrogen pump mode operation. Upon application of a constant current, an immediate ohmic resistance decrease of the membrane near the anode is observed, accompanied by a corresponding increase near the cathode side. This is a direct evidence of migration of the acid anions via the vehicle mechanism of the conductivity, resulting in an accumulation of acid molecules at the anode side and depletion at the cathode side. Both resistances reach a steady state value after a prolonged period of measurement, apparently balanced by the back diffusion of the acid molecules. The phenomenon is magnified at higher current densities and with increased thickness of the overall membrane, which is of significance in quantitative understanding of the proton conductivity mechanism e.g. for determination of the anionic transference number.The finding provides a technique to monitor the acid redistribution within the membrane as a basis for an engineering solution to address the long-term durability of fuel cells built around phosphoric acid doped polymer membranes.

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“…Therefore, various modified approaches for PBI‐based electrolytes have been developed in order to improve such as the mechanical strength without or with less sacrifice of the proton conductivity, and vice versa. The reported explorations, for instance, include increasing the molecular weight of the PBI polymer, fabrication of composite membranes with nano inorganic compounds, synthesis of PBI variants, ionic and covalent crosslinking of the PBI chains …”

Section: Introductionmentioning

confidence: 99%

Strengthening Phosphoric Acid Doped Polybenzimidazole Membranes with Siloxane Networks for Using as High Temperature Proton Exchange Membranes

Yang

Gao

Wang

et al. 2017

Macro Chemistry & Physics

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Two silane compounds, i.e., ((chloromethyl)phenylethyl)trimethoxysilane (Ph‐Si) and 3‐chloropropyltriethoxysilane (Pr‐Si), are employed as covalent crosslinkers to fabricate high temperature proton exchange membranes based on polybenzimidazole (PBI) in order to better understand the correlation between the structure and the property of the crosslinked membranes. All the crosslinked PBI membranes display longer morphology durability over the neat PBI membrane toward the radical oxidation. The crosslinked membranes with the crosslinker containing a rigid group of phenylene (PBI‐Ph) show superior acid doping level, high conductivity, and excellent mechanical strength simultaneously, comparing to those with the crosslinker having a flexible alkyl chain (PBI‐Pr) and the pristine PBI based membrane. The technical feasibility for using as high temperature proton exchange membranes is demonstrated by the acid doped crosslinked PBI‐Ph membranes via fuel cell tests.

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Amino‐Functional Polybenzimidazole Blends with Enhanced Phosphoric Acid Mediated Proton Conductivity as Fuel Cell Electrolytes

Cited by 15 publications

References 54 publications

Fuel Cell Electrolytes of Polybenzimidazole Membranes Cross‐linked with Bis(chloromethyl) Arenes

Fuel Cell Electrolytes of Polybenzimidazole Membranes Cross‐linked with Bis(chloromethyl) Arenes

Probing phosphoric acid redistribution and anion migration in polybenzimidazole membranes

Strengthening Phosphoric Acid Doped Polybenzimidazole Membranes with Siloxane Networks for Using as High Temperature Proton Exchange Membranes

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