bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Archetype: Opportunities of Pemion® Fully Hydrocarbon Ionomer and Composite Membranes in Proton-Exchange Membrane Fuel Cell Applications
Authors: Britton Benjamin 
Published: December 2024

Hydrogen fuel cells are a critical technology for the renewable energy transition, pairing with green hydrogen to represent the most economic and scalable power generation for many applications, in particular ‘heavy duty’ systems such as commercial trucking, aviation, shipping, remote operations such as mining, and the replacement of diesel generators. Perfluorosulfonic acid (PFSA) polymers as membrane and ionomer in the catalyst layer today represent the fundamental building blocks of proton-exchange membrane fuel cells (PEMFCs) and a broad range of electrochemical systems including PEM water electrolyzers (PEMWE). However, potential regulation and liabilities related to the production of environmentally mobile fluorinated materials represent a potential bottleneck to the scaling of these critical systems for the renewable energy economy. Acid-functionalized small molecules that are used as process aides and expelled as degradation products are particularly concerning and warrant direct or indirect replacement by non-fluorinated or ‘hydrocarbon’ chemistries. Sulfonated poly(arylene) ionomers exhibit exemplary stability and a the only presently commercialized material of this category, Pemion®, promises to enable to a long-sought step-change in system-level temperature hitherto limited by the physical properties of PFSAs as well as increase durability due to preferential chemical properties.
This presentation highlights the similarities and major divergences of the properties of hydrocarbon PEM Pemion®, comparing the physical and electrochemical properties of an ePTFE-reinforced product PF1-HLF8-15-X with those of hydrocarbon-reinforced membranes of various chemistries and production methods, as well as comparing PFSA- and hydrocarbon-based ionomers. Preliminary sub-scale work determining the structure-property relationships within Pemion® ‘fully hydrocarbon’ systems preliminarily demonstrate industrially relevant performances (i.e. sub-scale peak power densities >1 W/cm²) even in ‘hot and dry’ conditions, with a substantial (>50%) reduction in measured hydrogen permeability. The potential for system impacts of higher operational temperatures, increased liquid permeation, non-annealable electrode structures, and reduced gas permeation will be discussed, and preliminary data including multi-day comparisons with PFSA-based systems at operational temperatures ≥110 °C presented.
Phosphoric Acid-Doped Ion-Pair High-Temperature Proton Exchange Membranes Based on Polyphenylene Copolymer
Authors: Park Heemin , Kim Youngkwang , Kim Yu Seung , Bae Chulsung 
Published: December 2024

High-temperature proton exchange membrane fuel cell (HT-PEMFC) using hydrogen fuel has multiple advantages, such as faster reaction kinetics, high impurity tolerance to the catalyst, and simple water and thermal management than low-temperature proton exchange membrane fuel cell (LT-PEMFC). Polybenzimidazole (PBI) based phosphoric acid (PA)-doped membranes are the most common membrane for HT-PEMFC, because they have excellent chemical and thermal stability, and provide relatively usable conductivity for HT-PEMFCs. However, the PBI-based PA-doped membranes still suffer from reduction in conductivity at temperatures of 140–180 ˚C and high relative humidity due to acid leaching.
Herein, we have developed a novel polyphenylene-based ion-pair PA-doped membrane with excellent chemical and mechanical stability by functionalizing a polyphenylene-based copolymer with quaternary ammonium, followed by membrane casting. Due to a combination of the all-carbon backbone structure and high molecular weight of the polymer, it shows good chemical and mechanical stability of the membrane and great performance in HT-PEMFCs. We also fine-tuned the properties of the PA-doped membrane, such as proton conductivity and mechanical strength, by manipulating the ion exchange capacity (IEC) and crosslinking density of the polymer. The novel polyphenylene-based ion-pair PA-doped membranes were characterized in terms of IEC, PA doping level, area swelling ratio, PA uptake, proton conductivity, and mechanical properties. Overall, this study will present a new class of HT-PEMs with high fuel cell performance and excellent stability.
Controlling Flooding and Parameter Sensitivity in an Anion Exchange Membrane Fuel Cell Using a Triblock Copolymer Membrane and Matched Ionomers
Authors: Herring Andrew M. , Ponnada Srikanth , Kuo Mei-Chen 
Published: December 2024

While there has been much interest in the proton exchange membrane (PEM) fuel cell, its wide spread use has been restricted by cost, durability, fuel versatility issues, and the environmental consequences of using perfluorosulfonic acid polymers as the membrane and ionomer. This is primarily because catalyst based on Pt are nessecary in a PEM fuel cell on both the anode and the cathode and reactive oxygen species chemically degrade the cell. Alkaline catalysis in fuel cells has been demonstrated with non-precious metal catalysts, and a variety of fuels beyond H2 and methanol. Alkaline fuel cells (AFCs), based on aqueous solutions of KOH, have serious drawbacks associated with system complexity, low system power densities and carbonate formation. Anion exchange membrane (AEMs) fuel cells have a number of advantages over both PEM fuel cells and traditional AFCs. Great strides have been made in ionic conductivity and durability in AEMs and fuel cells with reduced precious metal loadings have been demonstrated. However, AEM fuel cells have significant water management issues, as water is both a reactant and a product leading to flooding and control issues.
We have developed a triblock copolymer Poly (vinylbenzyl-N-methylpiperidinium carbonate)-b-polyethylene-b-poly(vinylbenzyl-N-methylpiperidinium carbonate)as a robust, high performance, durable, and scalable AEM. We have modified the block ratios and ion exchange capacity of this material to show excellent performance and durability in both electro-desalination and water electrolysis. Despite the materials potential, we have only occasionally tested it as a fuel cell membrane. We have now begun to throughly evaluated the material in 5 cm2 H2/O2 fuel cell. Initial experiments showed good potential performance but were hampered by severe flooding of the electrodes. We will present a materials approach to solving this problem by investigating various related ionomers in the electrodes. Both variations of the polymer used to fabricate the membrane and a random co-polymer derived from polymethylbutylene and poly(vinylbenzyl-N-methylpiperidinium) were investigated. The effect of loading and ionomer ion exchange capacity on the performance of the fuel cell and the relationship between these properties will be reported.
Hydrocarbon Fuel Cell Membranes: Do We Need New Chemical Durability Testing Protocols?
Authors: Han Zongyi , Nemeth Tamas , Yandrasits Michael , Ren Hong , Bangay William , Gubler Lorenz 
Published: December 2024

Hydrocarbon proton exchange membranes (PEMs) for fuel cells have recently received increased attention due to growing environmental concerns about the use of per- and polyfluoroalkyl substances. The chemical accelerated stress test (AST) protocol for membranes developed by the US Department of Energy (DOE), which is based on the understanding of the degradation mechanism of perfluoroalkylsulfonic acid PEMs, has been widely adopted to assess newly developed hydrocarbon PEMs. However, due to different polymer chemistry and membrane degradation mechanisms, the DOE chemical AST protocol may not be suitable for hydrocarbon PEMs.
In this study, the influence of two key operating parameters, i.e. relative humidity (RH) and O2 partial pressure (p
O2), on the chemical degradation of hydrocarbon PEMs was investigated in order to design a more suitable chemical AST protocol for hydrocarbon PEMs. Sulfonated poly(ether ether ketone) (SPEEK) was selected as a representative material for non-fluorinated hydrocarbon PEMs. Solution-cast membranes of ~22 μm thickness were wet-assembled in a single fuel cell (16 cm2 active area) for fixed time (4 days) open circuit voltage (OCV) holding tests at different RHs and p
O2. Under 100% RH, H2/O2, the membrane failed the fastest within 40 hours (Figure 1a). This could be related to higher gas crossover (Figure 1b), which leads to more oxidative radicals, such as HO•, being generated. Fuel cell effluent water was periodically collected from both the anode and cathode sides for analysis by UV-vis spectroscopy and ion chromatography (IC). Hydroquinone-like degradation products were detected by UV-vis spectroscopy. Furthermore, under 100% RH, H2/O2, the degradation products showed the strongest signal in the anodic effluent water. IC results of sulfate ion release suggested that the higher the RH (also p
O2), the more severe the membrane degradation. Post-test ion exchange capacity (IEC) measurements showed that the average IEC loss rate is the highest under 100% RH, H2/O2 (~0.15 %/h), while the lowest under 30% RH, H2/air (~0.01 %/h), again indicating that 100% RH, H2/O2 could be a promising protocol for AST of hydrocarbon PEMs.

Figure 1
Development of Highly Durable Anion Exchange Membrane and the Utility for Aemwe Cells
Authors: Yanagibashi Naoki , Nagatsuka Shinya , Ozawa Yuki , Nakano Megumi , Sato Hiroyuki , Nishikwa Keiji , Nagashima Kodai , Uchida Katsuya , Miyanishi Shoji , Yamaguchi Takeo 
Published: December 2024

Anion exchange membrane water electrolysis is of great interest in terms of the environmental impact and the cost because it does not need precious metal-based catalysts and corrosion-resistant components. But, it is difficult to satisfy all the performance requirements for anion exchange membranes (AEMs). There are three major performance requirements for AEMs, high ion conductivity, high durability, and low cost and so on. Therefore, further development of AEMs is still needed.
Yamaguchi et al. have been researched the polyfluorene-based AEMs with high alkaline durability [1,2]. We are working on the practical application of their AEMs technology, and have been improving quality by optimizing the synthesis process and examining the film forming method, and examining scale-up for cost reduction. In addition, we prepared the test stand to evaluate the water electrolysis performance of AEMs, and we expanded our water electrolysis evaluation technology by introducing spray coater for the catalyst layer optimizing that of formation process, and the water electrolysis evaluation system.
Based on the report by Yamaguchi et al., we developed the AEM. The water electrolysis performance of the MEA using the AEM was below 1.75V at 1A/cm2 in 1M KOH solution at 80℃, which is equivalent to that of commercial AEMs. To compare the durability of AEMs, the water electrolysis performance was evaluated after soaking in 1M KOH solution at 80℃. Water electrolysis performance after durability test was better than that of commercial aromatic AEMs(Figure.1(a)). The performance of the AEM was slightly changed at 200 hours, but after that, there was almost no change in the performance at 2000 hours, and the increase in voltage was less than 3% compared to the initial performance(Figure.1(b)). On the other hand, the voltage of commercially available aromatic AEM increased by 140% at 1000 hours. We confirmed the high durability of the polyfluorene-based AEMs. For the future, we would like to show the superiority of the AEMs in the continuous data of the water electrolysis durability test in the cell.

References

[1] Miyanishi, T. Yamaguchi, Highly conductive mechanically robust high Mw polyfluorene anion exchange membrane for alkaline fuel cell and water electrolysis application,
Polym. Chem.
11.3812-3820, 2020, DOI: 10.1039/D0PY00334D
[2] T. Yamaguchi et al, An Extremely Low Methanol Crossover and Highly Durable Aromatic Pore-Filling Electrolyte Membrane for Direct Methanol Fuel Cells,
Advanced Materials
19, pp. 592–596 ,2007

Figure1. The water electrolysis performance measured after soaking 1M KOH solution.
(a) i-V curve after durability test (b) Voltage retention rate against durability time

Figure 1
Understanding the Mechanism of Chemical Durability Enhancement through Modeling of Electrolyte Membranes with Improved Oxygen Barriers
Authors: Fukaya Norihiro , Suzuki Takahisa , Gautama Zulfi , Sasaki Kazunari , Nishihara Masamichi 
Published: December 2024

In pursuit of a carbon-neutral society, polymer electrolyte fuel cells (PEFCs) are gaining significant attention in commercial applications, particularly for heavy-duty vehicles. The system demands long-term durability to its components, especially for polymer electrolyte membranes (PEMs), which require further thinning in the future[1]. The chemical degradation of PEMs occurs because of the attack by radical species. It is posited that hydrogen peroxide, arising from the crossover of oxygen, contributes to the formation of radical species. We hypothesized that introducing a gas barrier layer (GBL) against oxygen into the PEM could suppress chemical degradation, and confirming this hypothesis through durability tests using a GBL sandwiched between PEMs [2]. In this study, we constructed a model having the GBL to understand the mechanism behind this enhanced durability.
According to the scanning electron microscopy (SEM) observations of the fabricated membrane electrode assembly (MEA) with the GBL (Fig. 1a), we constructed a 1D through-plane model of MEA (Fig. 1b). Species conservation equations were solved in each layer to calculate the potential and concentration. Reactions R1– R4 were assumed in the catalyst layers for the source terms of the conservation equations.

2H+ + 2e- → H2

(R1)

O2 + 4H+ + 4e- → 2H2O
(R2)

O2 + 2H+ + 2e- → H2O2

(R3)

H2O2 + 2H+ + 2e- → 2H2O
(R4)

We compared the distribution of hydrogen peroxide concentration in MEAs with and without the GBL by using our model. In MEAs with the GBL, a significant concentration (expressed by an equivalent partial pressure) gradient developed, leading to a reduction in oxygen concentration on the anode side (Fig. 2a) compared to those without the GBL (Fig. 2b). This indicates a lower oxygen flux towards the anode, which resulted in a reduced rate of hydrogen peroxide formation and lower concentrations in the MEA with the GBL. These results suggest that the presence of the GBL prevented degradation and enhanced the durability of the MEA.
In the presentation, we will present the details of the model and discuss strategies for further enhancing the durability of MEAs with the GBL by showing various case studies.

Figure 1
(Invited) Designing Cation Coordination from Bulk to Interface for Next-Generation Battery Electrolytes
Authors: Connell Justin G. 
Published: December 2024

As demand surges for batteries that can deliver increased capacity and charging rates for electric vehicles, as well as low costs and long lifetimes for storing renewable energy on the grid, new electrolytes that can operate reversibly at increasingly aggressive conditions are essential. We have recently demonstrated that systems containing multiple anions represent a promising path forward for new electrolyte discovery. Specifically, differences in anion association strength to the working cation and the formation of mixed anion contact ion pairs (CIPs) in the electrolyte bulk via emergent solvation behavior can be used to independently tune the overpotentials for metal plating and stripping and improve overall performance. Furthermore, the addition of co-solvents can significantly modify cation coordination at the electrified interface, even in the absence of any measurable changes to bulk solvation structure. These concepts have been elaborated via a multimodal approach spanning electrochemical analysis, in situ/ex situ bulk and surface spectroscopy, and computational approaches. We have further demonstrated that cooperative anion effects are active for multiple working cations, which suggests a more general set of electrolyte design rules likely exists. Several examples will be presented where computationally guided exploration of anion combinations has led to the discovery of new, dual-anion electrolytes whose performance exceeds that of their single anion analogues.
_______________________
The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan. http://energy.gov/downloads/doe-public-access-plan
Overvoltage Analysis of the Heterogeneous-Structure Effect of PEMFC Cathodes
Authors: Tanaka Akihisa , Inoue Gen , Nagato Keisuke 
Published: December 2024

Catalyst layer (CL) design of polymer electrolyte membrane fuel cells (PEMFCs) requires an understanding of the contribution of each physicochemical process to overvoltage. In this study, the effect of the heterogeneous CL structure on the overvoltage of each process was numerically analyzed. Using a previously validated model [1], a heterogeneous CL structure was constructed based on the fabrication conditions of an actual CL. The Pt catalyst was distributed, and the effective diffusion coefficients of oxygen and vapor and the effective conductivities of protons and electrons were calculated locally based on the void, ionomer, and carbon structures. For comparison, a homogeneous CL structure with an averaged local Pt content, effective diffusion coefficients, and effective conductivities was constructed. Subsequently, the reaction and mass transport were calculated using the heterogeneous and homogeneous models, followed by overvoltage separation based on local power losses. Figure 1 shows the local current density distributions and overvoltage differences of the two models calculated at a cell temperature (Tcell) of 80 °C, relative humidity (RH) of 50%, and an oxygen partial pressure (pO2) of 0.2 atm. The local current density in heterogeneous model has a discrete distribution, while that in homogeneous model has a continuous distribution. Although the activation overvoltage is smaller in the heterogeneous model, the overvoltage difference is relatively small. In contrast, the overvoltages of oxygen and proton transport are larger in the heterogeneous model. Furthermore, these mass transport-related overvoltages increase with increasing current density. In this contribution, the effect of the heterogeneous CL structure on each overvoltage will be comprehensively discussed by varying the operating conditions.
Reference
[1] A. Tanaka, G. Inoue, K. Nagato, and M. Nakao, Available at SSRN: http://dx.doi.org/10.2139/ssrn.4745148.

Figure 1
Regulating Assembly of Porous Electrode Catalyst Layers
Authors: Srivastav Harsh , Radke Clayton J. , Weber Adam Z. 
Published: December 2024

Polymer-electrolyte fuel cells (PEFCs) demonstrate remarkable potential in replacing non-renewable energy resources in paving the way for a sustainable future. PEFCs have fairly high efficiencies and energy densities, making them feasible for applications such as transportation and energy storage. The most expensive units of the PEFCs are the catalyst layers, traditionally composed of platinum interspersed on a carbon support with a perfluorosulfonic acid (PFSA) which stabilizes the ink dispersions as well acts as a binder for the dried catalyst layers. Despite the great importance of optimizing the composition of the catalyst layer to improve the practicality of PEFCs, predicting the performance of the final structure of the fuel cell remains a challenge.
In this talk, we outline an approach to predict key properties of the catalyst layers such as the porosity and particle sizes that compose it through mathematical modeling of the ink properties. We discuss a kinetics-based algorithm based on interacting particles that simultaneously solves for the size distributions of the particles and the pH of the ink, a parameter that can be used for verification. The results of the aggregation formulation will be fed into calculations to determine fundamental properties of the catalyst layer, such as porosity through a void fraction calculation. To verify the accuracy of this approach, we will compare against experimental data for varying concentrations and solvents. The insights gained from these considerations will enable efficient design of future catalyst layers.
Utilizing Distribution of Relaxation Times Analysis for Water Content Management in Anion Exchange Membrane Fuel Cells
Authors: Haodong Huang , Zhao Tianshou , Zeng Lin 
Published: December 2024

Amid escalating concerns over air pollution and energy scarcity, Anion Exchange Membrane Fuel Cells (AEMFCs) are increasingly recognized as a viable solution for power generation, offering high efficiency, and zero emissions. Water plays a critical role within these systems as a reactant, consumed at the cathode and generated at the anode. This process can lead to disparities in water content, potentially compromising the cell's performance. Therefore, it is imperative to maintain optimal water distribution to facilitate effective charge transport and enhance electrochemical reaction kinetics. Consequently, devising a robust water management strategy is essential to ensuring the sustained operation and longevity of AEMFCs.
Characterizing the water conditions at the anode and cathode under various operational states (normal, drying, or flooding) is a pivotal step underpinning effective water management strategies. Electrochemical Impedance Spectroscopy (EIS) provides a valuable tool for examining various resistances associated with kinetics, mass transport, and ohmic losses across different operational timescales, thereby facilitating a detailed assessment of water transport dynamics. Traditional analyses of EIS data often depend on equivalent circuit models, which require predefined assumptions and the selection of initial components. However, this study adopted the Distribution of Relaxation Times (DRT) methodology for its exceptional capability to disaggregate components, enabling a more nuanced analysis of the polarization processes. The DRT methodology was applied to scrutinize the patterns of loss and variation within each polarization process under varying water flooding and drying conditions at the anode and cathode. Moreover, to deepen our comprehension of how water content influences mass transport and electrochemical reaction kinetics, a three-dimensional multi-physics model for AEMFCs was developed. This model comprehensively integrates considerations of water phase transitions, heat and mass transfer, as well as the transport of liquid and dissolved water, alongside electrochemical reactions. These efforts collectively forge a comprehensive and systematic framework to advance the application of the distribution of relaxation times in optimizing fuel cell performance.