Poly(meta/para-Terphenylene-Methyl Piperidinium)-Based Anion Exchange Membranes: The Effect of Backbone Structure in AEMFC Application

Mayadevi, T.S.; Sung, Seounghwa; Varghese, Listo; Kim, Tae‐Hyun

doi:10.3390/membranes10110329

Cited by 31 publications

(23 citation statements)

References 50 publications

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“…Mayadevi et al synthesized a series of poly(terphenyl-piperidinium)s with varying ratios of para -terphenyl and meta -terphenyl units in the backbone (PPip5-m) . With equal para -terphenyl and meta -terphenyl incorporation, PPip5-50 demonstrated a hydroxide conductivity of 53.5 mS/cm at 20 °C and 130 mS/cm at 80 °C, which was higher than the conductivities exhibited by PPip5-20 and PPip5-60 despite having similar experimental IECs.…”

Section: Alkaline Membrane/ionomer Design and Synthesismentioning

confidence: 99%

Electrocatalysis in Alkaline Media and Alkaline Membrane-Based Energy Technologies

et al. 2022

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Hydrogen energy-based electrochemical energy conversion technologies offer the promise of enabling a transition of the global energy landscape from fossil fuels to renewable energy. Here, we present a comprehensive review of the fundamentals of electrocatalysis in alkaline media and applications in alkaline-based energy technologies, particularly alkaline fuel cells and water electrolyzers. Anion exchange (alkaline) membrane fuel cells (AEMFCs) enable the use of nonprecious electrocatalysts for the sluggish oxygen reduction reaction (ORR), relative to proton exchange membrane fuel cells (PEMFCs), which require Pt-based electrocatalysts. However, the hydrogen oxidation reaction (HOR) kinetics is significantly slower in alkaline media than in acidic media. Understanding these phenomena requires applying theoretical and experimental methods to unravel molecularlevel thermodynamics and kinetics of hydrogen and oxygen electrocatalysis and, particularly, the proton-coupled electron transfer (PCET) process that takes place in a proton-deficient alkaline media. Extensive electrochemical and spectroscopic studies, on single-crystal Pt and metal oxides, have contributed to the development of activity descriptors, as well as the identification of the nature of active sites, and the rate-determining steps of the HOR and ORR. Among these, the structure and reactivity of interfacial water serve as key potential and pH-dependent kinetic factors that are helping elucidate the origins of the HOR and ORR activity differences in acids and bases. Additionally, deliberately modulating and controlling catalyst−support interactions have provided valuable insights for enhancing catalyst accessibility and durability during operation. The design and synthesis of highly conductive and durable alkaline membranes/ionomers have enabled AEMFCs to reach initial performance metrics equal to or higher than those of PEMFCs. We emphasize the importance of using membrane electrode assemblies (MEAs) to integrate the often separately pursued/optimized electrocatalyst/support and membranes/ionomer components. Operando/in situ methods, at multiscales, and ab initio simulations provide a mechanistic understanding of electron, ion, and mass transport at catalyst/ionomer/membrane interfaces and the necessary guidance to achieve fuel cell operation in air over thousands of hours. We hope that this Review will serve as a roadmap for advancing the scientific understanding of the fundamental factors governing electrochemical energy conversion in alkaline media with the ultimate goal of achieving ultralow Pt or precious-metal-free highperformance and durable alkaline fuel cells and related technologies.

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Section: Alkaline Membrane/ionomer Design and Synthesismentioning

confidence: 99%

Electrocatalysis in Alkaline Media and Alkaline Membrane-Based Energy Technologies

et al. 2022

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“…The rationale for the high stability is the low ring strain of the six-membered rings in combination with a high activation energy of the transition states in the Hofmann β-elimination and substitution reactions induced by hydroxide attack . Inspired by this influential work, many different AEMs based on DMP and ASU cations have been prepared and studied by us ,, and other research groups. ,, The results have shown high alkaline stability in both ex situ experiments − and fuel cell evaluations. − For example, we , and others ,,, have prepared and investigated poly(arylene piperidinium) by polyhydroxylalkylations involving piperidone, which provides an ether-free polymer incorporating DMP cations in the backbone after methylation of the piperidine rings. Alternatively, cyclo-quaternization with 1,5-dibromopentane results in spirocyclic ASU cations. , …”

Section: Introductionmentioning

confidence: 99%

“…11,36,37 The results have shown high alkaline stability in both ex situ experiments 38−40 and fuel cell evaluations. 41−44 For example, we 16,45 and others 42,44,46,47 have prepared and investigated poly(arylene piperidinium) by polyhydroxylalkylations involving piperidone, which provides an ether-free polymer incorporating DMP cations in the backbone after methylation of the piperidine rings. Alternatively, cyclo-quaternization with 1,5-dibromopentane results in spirocyclic ASU cations.…”

Section: Introductionmentioning

confidence: 99%

Poly(arylene piperidine) Anion Exchange Membranes with Tunable N-Alicyclic Quaternary Ammonium Side Chains

Pan

Pham

Jannasch

2021

ACS Appl. Energy Mater.

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To develop anion exchange membranes (AEMs) that combine high chemical stability and hydroxide conductivity, we have designed and prepared poly(arylene piperidine)s carrying tunable mono- or dicationic side chains. Poly(biphenyl piperidine) and poly(biphenyl N-methylpiperidine), respectively, were first synthesized by superacid-catalyzed polyhydroxylalkylations. Subsequently, the piperidine rings of these polymers were reacted with bromoalkylated N,N-dimethylpiperidinium (DMP) and 6-azonia-spiro[5.5]undecane (ASU) cations, respectively. This gave two series of AEMs in which the polymer backbone contained tertiary and quaternary piperidine rings, respectively, resulting in mono- and dicationic side chains in series 1 and 2, respectively. In series 1, both the piperidine rings in the backbone and the pendant cations in the side chains showed excellent alkaline stability, resulting in AEMs, which retained more than 92% of the cations after storage in 2 M NaOH at 90 °C during 30 days. In addition, these AEMs reached a hydroxide conductivity up to 131 mS cm–1 at 80 °C. Benefiting from a high local ionic concentration through the dicationic configuration, the AEMs in series 2 reached a higher conductivity, almost 170 mS cm–1 at 80 °C at moderate water uptake and swelling. Still, these AEMs were more vulnerable to hydroxide attack than the ones in series 1 because of the quaternary piperidinium groups placed in the polymer backbone. In conclusion, the AEMs in series 1 can be employed in electrochemical devices that operate under harsh alkaline conditions, while those in series 2 should be preserved for less aggressive alkaline conditions.

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“…Recently, an anion-exchange membrane (AEM) electrolyzer cell (AEMEC) has received significant attention with breakthrough accomplishments. − The utilization of AEM offers the benefits of both PEM electrolysis and traditional concentrated-solution electrolysis with the circulating liquid electrolyte. In addition, hydrocarbon membranes used in AEMECs are of low cost compared to the perfluorinated membranes in PEMECs. ,− As shown in Figure a, an AEMEC mainly consists of two electrodes of the cathode and the anode separated by the AEM. A typical electrode is composed of a catalyst layer (CL) and a liquid/gas diffusion layer (LGDL), where the LGDL is the key component sandwiched between the CL and the bipolar plate .…”

Section: Introductionmentioning

confidence: 99%

Engineered Thin Diffusion Layers for Anion-Exchange Membrane Electrolyzer Cells with Outstanding Performance

et al. 2021

ACS Appl. Mater. Interfaces

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Anion-exchange membrane electrolyzer cells (AEMECs) are one of the most promising technologies for carbonneutral hydrogen production. Over the past few years, the performance and durability of AEMECs have substantially improved. Herein, we report an engineered liquid/gas diffusion layer (LGDL) with tunable pore morphologies that enables the high performance of AEMECs. The comparison with a commercial titanium foam in the electrolyzer indicated that the engineered LGDL with thin-flat and straight-pore structures significantly improved the interfacial contacts, mass transport, and activation of more reaction sites, leading to outstanding performance. We obtained a current density of 2.0 A/cm 2 at 1.80 V with an efficiency of up to 81.9% at 60 °C under 0.1 M NaOH-fed conditions. The as-achieved high performance in this study provides insight to design advanced LGDLs for the production of low-cost and high-efficiency AEMECs.

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Poly(meta/para-Terphenylene-Methyl Piperidinium)-Based Anion Exchange Membranes: The Effect of Backbone Structure in AEMFC Application

Cited by 31 publications

References 50 publications

Electrocatalysis in Alkaline Media and Alkaline Membrane-Based Energy Technologies

Electrocatalysis in Alkaline Media and Alkaline Membrane-Based Energy Technologies

Poly(arylene piperidine) Anion Exchange Membranes with Tunable N-Alicyclic Quaternary Ammonium Side Chains

Engineered Thin Diffusion Layers for Anion-Exchange Membrane Electrolyzer Cells with Outstanding Performance

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