bluuebunny/crossref_metadata_2025_split huggingface dataset:
Unraveling Chemical Degradation in PEM Water Electrolyzers: Factors, Stressors, and Membrane-Level Solutions for Enhanced System Lifespan
Authors: Chen Yingying , Setzler Erin , Barrett Brian , Agapov Alexander 
Published: December 2024

Proton Exchange Membrane (PEM) water electrolyzers stand at the forefront of sustainable energy generation, offering a promising pathway toward carbon-neutral fuel production. Commercial systems require operation times > 50,000 hours. However, chemical degradation of PEMs remain a critical challenge affecting the longevity of the systems. One expected mode of degradation is that hydrogen peroxide is formed at the cathode in PEM water electrolyzers due to the low potentials and presence of platinum, hydrogen, and crossover oxygen. The hydrogen peroxide can participate in Fenton’s reactions to produce radicals that attack vulnerable sites of the ionomer. The radicals may be formed in the membrane or the electrodes and degrade the ionomer in both locations. Furthermore, the impact of degradation products, like short-chain ionomer fragments or hydrogen fluoride, on other system components is unknown. Overall, the underlying mechanisms and the key impact factors involved are not yet fully understood.
Moreover, new product development for PEMs face the challenge to deliver robust products within shorter development timelines than the actual system operation allows. Consequently, there’s a pressing need for accelerated stress testing (AST) to evaluate new materials and assess mitigation effectiveness against specific membrane failure modes. Understanding the factors that accelerate chemical degradation and deconvoluting sources of performance loss is necessary for developing AST protocols.
In this study, we intended to elucidate the intricate mechanisms underlying chemical degradation in PEM water electrolyzers. Chemical degradation is monitored through the loss of fluoride ions and post-mortem characterizations like SEM and FTIR. We explore the impact of various environment and operating parameters on degradation rate, such as water quality/contamination, water flow rate, operating temperature and pressure, and current density / voltage. These factors are explored in a flow-through system where concentration of water is needed for a detectable fluoride signal. Methods for concentrating water will be discussed.
By elucidating the factors impacting chemical degradation and identifying key stressors, insights from this study can be used to develop informative AST protocols, essential for accelerating the evaluation of materials with improved conductance-crossover-durability tradeoff, and therefore enabling more robust and efficient PEM water electrolyzer systems.
Overcoming Challenges in Ion-Pair Membrane Technology: Advancements in Fuel Cells and Electrochemical Hydrogen Pumps
Authors: Chhetri Manjeet , Kim Youngkwang , Maurya Sandip , Park Hyounmyung , De Castro Emory S. , Kim Yu Seung 
Published: December 2024

The Membrane Electrode Assembly (MEA) stands as the pivotal element in electrochemical devices such as fuel cells and electrochemical hydrogen pumps (EHP). Notably, ion-pair High-Temperature Proton Exchange Membrane Fuel Cells (HT-PEMFCs) with reduced phosphoric acid concentrations within the MEA have been innovatively designed, allowing for the integration of diverse ion-conducting binders, known as ionomers, into both the cathode and anode electrodes [1]. This study delineates initial distinctions in MEA configurations among different device types (HT-Fuel cell and EHP, conducting a comprehensive analysis of performance disparities between traditional polybenzimidazole-based systems and various ion-pair proton exchange membranes [2].
Subsequently, a detailed exploration unfolds, focusing on the utilization of ion-pair membranes and different ionomer types for the three aforementioned devices. This comprehensive examination offers a unified comparative analysis encompassing ionomer type, membrane thickness, catalyst:ionomer ratio, and phosphoric acid doping levels, particularly in the context of performance at intermediate temperatures (160℃). Conclusions are drawn based on results derived from both half-cell and single-cell evaluations. Finally, overarching guidelines are presented to inform the formulation of high-performance MEA configurations tailored for ion-pair HT-PEMFCs and EHPs.

References:

[1] Lim, K. H.; Lee, A. S.; Atanasov, V.; Kerres, J.; Park, E. J.; Adhikari, S.; Maurya, S.; Manriquez, L. D.; Jung, J.; Fujimoto, C.; Matanovic, I.; Jankovic, J.; Hu, Z.; Jia, H.; Kim, Y. S. Protonated phosphonic acid electrodes for high power heavy-duty vehicle fuel cells, Nature Energy, 7, 248 (2022).
[2] Lim, K, H; Matanovic, I; Maurya, S; Kim Y; De Castro E. S; Jang, J-H; Park, H; Kim, Y.S. High Temperature Polymer Electrolyte Membrane Fuel Cells with High Phosphoric Acid Retention. ACS Energy Lett., 8, 1, 529–536 (2023).
Surface Wetting Properties of Lithium Anode Characterized Using Laser Scanning Confocal Microscopy
Authors: Yakovleva Marina , Xia Jian , Fitch Brian 
Published: December 2024

Surface wettability between the lithium metal anode and liquid electrolyte is a critical performance characteristic. Poor wettability can result in nonuniform stripping and deposition of lithium metal, nonuniform SEI formation, formation of dead lithium and; thus, shorter cycle life. Imaging techniques such as laser-induced fluorescence imaging using laser scanning confocal microscopy (LSCM), have become a valuable tool for investigating the surface properties of lithium metal anodes.1 Laser scanning confocal microscopy is an advanced microscopy technique that allows improved depth resolution relative to traditional optical microscopy.
Arcadium Lithium Corporation has developed LIOVIX®printable lithium technology, a formulation that can be printed, at industrial speed, on most common substrates, such as Cu foil to produce thin lithium metal foil with thickness in the range of 5 µm to 50 µm with no limitation in width.2 LIOVIX®-based lithium film has a different microstructure when compared to a commercial foil (Figures 1a and 1b). LIOVIX-based thin foil retains rheology modifiers used in the formulation that serve as a 3D skeleton. This unique structure can change lithium metal surface plating behavior. Therefore, the 3D structure might mitigate the growth of dendritic lithium, reduce mechanical degradation, and improve safety and cycle life of the battery.
LSCM was used for in-situ, in operando observations of the difference in surface properties and wettability properties of commercial lithium foil and LIOVIX-based lithium foil (Figures 1c and 1d). Lithium metal surface is dynamic and prone to forming various structures and compounds, depending on the conditions it is exposed to. The results showed that LIOVIX-based foil lithium activity is more homogenous and had a shallower interaction when compared to the commercial lithium foil. This potentially signifies more uniformity to the lithium activity in LIOVIX-based foil vs. commercial lithium foil; thus, more uniform surface activity within a battery system.
Reference

Nishikawa et al., 2010 J. Electrochem. Soc. 157 A1212

Yakovleva et al., Battery utilizing printable lithium, U.S. Patent 11, 824, 182, B2, Nov. 21, 2023

Figure 1. Microscope image of A) LIOVIX® -based lithium foil (20um), B) commercial lithium foil (20um); and 3D Confocal microscope images of C) LIOVIX®-based lithium foil (20um) and D) commercial lithium foil (20um).

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Development of in Operando Technique for Modification TiO2 Based Li-Ion Anode Materials Application
Authors: Shen Yu-Min , Ho Cheng-Hsun , Chong Zhen , Yang Chih-Lung , Chang Chia-Chin , Huang Jow-Lay 
Published: December 2024

TiO2 has emerged as a focus in the research of new anode electrode materials for lithium-ion batteries due to its exceptional stability, cycling performance, and environmental friendliness. However, the fatal issue of TiO2 series anode electrode materials is their relatively low specific capacity (335 mAh/g). In response to this challenge, our research team has proposed surface modification methods to enhance their capacity, such as SnO2@TiO2 and MoOx@TiO2. This study found that the initial delithiation capacity of TiO2 modified with Tin Dioxide and MoOx at rate of 0.1C reached 440 and1273 mAh/g, respectively, with lithiation capacity of 706 and 780 mAh/g, respectively. The capacity retention can remain at 80% after 100 cycles for both of the samples. While successful surface modification of TiO2 negative electrode materials has been achieved in this study, mechanisms of sustaining high capacity and enhancing initial Coulombic efficiency remain crucial topics for discussion. We will employ in-situ analysis techniques to investigate the phase changes of lithium ions during charge and discharge processes and identify key factors for improving initial Coulombic efficiency.
In evaluating the influence of lithium-ion insertion/extraction, our team utilized in-situ XRD analysis as the field technique. The XRD results revealed that besides the irreversible formation of Li0.55TiO2 during charge and discharge processes leading to reduced discharge capacity, SnO2 exhibited reversible behavior during lithium-ion insertion/extraction, while in the MoOx series, overall phase transitions occurred as MoO2 and MoO3. Subsequently, our research team will conduct further computational analysis on the lithiation amount of SnO2 and MoOx. Addressing the issue of initial Coulombic efficiency, our team initially employed in-situ thermal analysis techniques to understand the heat absorption/release phenomena in the plateau region of surface-modified TiO2 and applied pre-lithiation techniques at different potentials. Through this approach, it was observed that pre-lithiation of surface-modified SnO2 at specific potential improved the initial Coulombic efficiency from 60% to 90%; while the pre-lithiated MoOx remained the initial Coulombic efficiency at 70%
By in-situ techniques, our research team aims not only to effectively enhance various properties of surface-modified TiO2 materials but also to establish their commercial viability in the future.
Keyword: modification TiO2 anode, in situ XRD, in situ thermal analysis, pre-lithiation
Computational Fluid Dynamics Analysis of Gas Crossover in an Alkaline Electrolyzer Using a Multifluid Model
Authors: Martinho Diogo Loureiro , Abdollahzadehsangroudi Mohammadmahdi , Berning Torsten 
Published: December 2024

Green hydrogen has emerged as a key solution for high-intensity energy storage, with various technologies introduced to facilitate its production, including alkaline electrolyzers (AWE), proton exchange membrane electrolyzers, and solid oxide electrolyzers. While each of these technologies presents unique strengths and weaknesses, alkaline electrolyzers are particularly noted for their cost-effectiveness and robust structure in hydrogen production. However, a comprehensive understanding of the internal dynamics of the electrolyzer during operation requires detailed modeling.
This study aims to delve into the dynamics of AWE, optimizing operational parameters and cell design to enable higher current operation without increasing voltage losses, thereby enhancing overall efficiency. Computational fluid dynamic modeling is employed to achieve this goal, focusing on gas bubble behavior within the electrolyzer, their impact on cell performance, and the dynamics of mass transfer between different phases.
One drawback of alkaline electrolyzers is the crossover of hydrogen and oxygen through the membrane, resulting in reduced hydrogen purity and increased hydrogen loss. The preset study investigates the effect of electrolyte saturation levels on crossover, highlighting its significance. Additionally, a parametric study is conducted, varying bubble diameter across simulations to further understand its implications.

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Proton Incorporation and Electrical Leakage in BaZrO3 and BaCeO3
Authors: Varley Joel , Ogitsu Tadashi , Li Meng , Rowberg Andrew 
Published: December 2024

Molecular hydrogen (H2) is a vital next-generation energy carrier, due to its high energy density, universal abundance, and ability to produce electricity in a fuel cell without greenhouse gas emissions. Critical to the adoption of hydrogen energy is the ability to produce H2 cleanly via the electrolysis of water. Solid oxide electrolyzer cells (SOECs) are attractive technologies to achieve this goal, as they can use excess thermal energy or other renewable energy sources to convert water into H2. However, the fundamental physics that determines the performance of SOECs—including sources of performance loss and degradation—is relatively poorly understood.
Here, we describe first-principles calculations based on hybrid density functional theory (DFT) aimed at studying efficiency loss in proton-conducting SOECs based on the oxide electrolytes BaZrO3 (BZO) and BaCeO3 (BCO). These materials are acceptor-doped with a trivalent element such as yttrium to introduce protons; however, such doping can also increase electrical leakage in devices, which limits their Faradaic efficiency. Our calculations describe the properties of localized polarons in BZO and BCO: hole polarons form favorably in both materials, while electron polarons are only stabile in BCO and in Ce-containing alloys. Under typical operating conditions, large concentrations of hole polarons may be present; therefore, to limit the risk of p-type electrical leakage, it is advantageous to avoid extreme oxygen-rich conditions and high dopant concentrations [1].
High ionic conductivity also requires large proton concentrations. We examine avenues to achieve this requirement by calculating the formation energy of protons and their concentrations under various conditions. Proton concentrations will be highest under wet conditions, with oxygen vacancies becoming more dominant under drier conditions. Encouragingly, higher protonation levels correlate with lower concentrations of hole polarons, implying lower electrical leakage with higher hydration levels. In addition to traditional protonation pathways, we also explore a novel hydrogenation mechanism via hydroxyl incorporation, which does not require acceptor doping. However, this process is unfavorable except under extremely wet conditions [2].
These results provide crucial insights for understanding the complex behavior of these materials in situ. Determining how to promote ionic conductivity at the expense of electrical leakage is critical to optimizing their performance in SOECs and related devices.
This work was performed under the auspices of the U.S. DOE by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
[1] A. J. E. Rowberg, M. Li, T. Ogitsu, J. B. Varley, Phys. Rev. Mater. 7, 015402 (2023).
[2] A. J. E. Rowberg, M. Li, T. Ogitsu, J. B. Varley, Mater. Adv. 4, 6233-6243 (2023).
Fluoride Ion Conductivity and Crystal Structure Analysis of Ba4Bi3F17 with Fluorite-Type Units
Authors: Hirakawa Saya , Shimoda Keiji , Kawaguchi Shogo , Orikasa Yuki , Zhong Chengchao 
Published: December 2024

All-solid-state fluoride ion batteries are attracting attention as an innovative next-generation battery that can replace lithium-ion batteries due to their high energy density. For fluoride ion conductor, three main types of crystal structures have been reported: fluorite-type, tysonite-type, and perovskite-type. Among these, fluoride ionic conductors with fluorite-type structure show the best conductivity. In fluorite-type BaF2, 4-coordinated fluoride ions are difficult to move within the crystal structure, and it has been reported that the addition of La3+ with different valence improves conductivity by inserting fluoride ions into interstitial sites within certain solid solution regions.[1] The addition of Bi3+ results in the formation of a cation-ordered structure Ba4Bi3F17 in certain solid solution regions, which has fluorite-type structural units derived from BaF2 in the structure. Reports on Ba4Bi3F17 are limited to its crystal structure[2] and there are no studies on it as an ionic conductor. In this study, the fluoride ion conductivity and fluoride ion conduction pathway of Ba4Bi3F17 was evaluated and compared with those of BaF2 with fluorite-type structure.
To synthesise Ba4Bi3F17, BaF2 and BiF3 were weighed in an Ar atmosphere, mixed for 10 min. After pressing into a φ10 pellet, it was wrapped in a Ta container and sealed in a quartz tube, following by calcining at 773 K for 24 hours. Samples were identified by powder X-ray diffraction and AC impedance measurements were performed to assess their conductivity.
Powder X-ray diffraction results showed that Ba4Bi3F17 was successfully synthesized and exhibited Fluoride ion conductor of 1.63 × 10−6 S cm−1 at 473 K. Further analysis of the fluoride ion conductor pathways showed that fluoride ions in Ba4Bi3F17 conduct in a four-coordinate to four-coordinate conduction pathway, which is different from the conventional four-coordinate to six-coordinate conduction pathway in BaF2 with fluorite-type structure. These results indicate that even the same structural unit can change fluoride ion conductor pathways depending on the surrounding environment.
[1] Kazuhiro Mori et. al., ACS Appl. Energy Mater., 2020, 3, 2873-2880
[2] E.N. Dommbrovski et. al., Solid State Chemistry, 2004, 177, 312-318
Regioselective Electrocatalytic Deuteration Reactions in PEM Reactor
Authors: Ashikari Yosuke , Yao Yiyuye , Mandai Kyoko , Nagaki Aiichiro 
Published: December 2024

Although organic chemistry has brought significant benefits to humanity by providing a wide range of chemicals, conventional production methods often generate a significant amount of chemical waste. As the need for sustainability increases, there is a growing demand for organic reactions that utilize fewer chemical reagents, resulting in reduced waste generation. In this context, electrochemical synthetic methods have garnered great attention in recent decades. Unlike general redox reactions in organic synthesis, which require stoichiometric amounts of oxidants and reductants, electrochemical oxidation and reduction utilize electricity as a substitute for these chemicals, leading to a reduction in chemical usage and waste production.
In industrial-scale synthesis, the characteristics of electro-organic synthesis, particularly its applicability in waste reduction, become increasingly important. However, scaling up electrochemical reactions presents a hurdle, as the reaction occurs on the surface of the electrodes, necessitating larger electrode surface areas. According to the square-cube law, as the reaction scale increases, the ratio of the electrode's surface area to the reaction volume decreases proportionally. This implies a physical limitation to scaling up electro-organic reactions.
To circumvent this limitation and enable scalable and sustainable synthesis, flow reactors offer a viable solution. Flow synthesis offers numerous benefits over conventional batch reactions and proves advantageous for scaling up. Flow reactors allow for the successive insertion of reactants into the reactor and subsequent passage outside, eliminating the need to enlarge the reactor to increase the reaction scale.
Herein, we report a flow electrosynthesis using a proton-exchange membrane (PEM) reactor. With the PEM reactor, water serves as the proton source for the hydrogenation and semi-hydrogenation of unsaturated compounds, as well as bis-deuterated alkenes via the semi-hydrogenation of alkynes using heavy water as a deuterium source. Additionally, we found that reductive deuteration reactions could be applicable to the dehalogenation of (hetero)aryl halides, thereby producing mono-deuterated compounds.
Electrochemical One-Pot Synthesis of Cyclic Oligoglucosamines
Authors: Endo Hirofumi , Rahman Azadur MD , Masaharu Ochi , Hamada Tomoaki , Kawano Takahiro , Sasaki Norihiko , Nokami Toshiki 
Published: December 2024

Carbohydrates are known as the third chain of life, following DNA and proteins, and their roles extend beyond energy and structural materials to function as pharmaceuticals and cell recognition molecules (1. Among carbohydrates, sugar chains that undergo intramolecular glycosylation are called cyclic oligosaccharides; for example, cyclodextrins are a well-known example composed of six or more D-glucose unit. By utilizing the inclusion ability and molecular recognition ability of the cavities within cyclodextrins, applications such as drug delivery systems, functional materials, and pharmaceuticals have been developed (2. These functional developments are achieved through functional group transformations, although the adaptability of these transformations is partially challenging from the perspective of identifying the reactivity of hydroxyl groups. Therefore, for further functional development, a bottom-up synthesis starting from the monosaccharide is required.
We have been focusing on the synthesis of cyclic oligosaccharides using D-glucosamine, which has an amino group at the 2-position of the pyranose ring (3. Although cyclic oligosaccharides are essentially repetitions of the same monosaccharide, sequential synthesis is required to distinguish between elongation and cyclization, leading to redundancy in the synthetic process. Therefore, we have focused on an organic electrochemical method (4, where we can control the initiation and termination of reactions by passing electric currents. To control both elongation and cyclization in one-pot, we synthesized building blocks containing 2,3-oxazolidinone, known to change its structure from the β-form to the α-form through thermodynamically controlled isomerization using acid (5. Using this building block, we achieved the synthesis of cyclic oligosaccharides containing α-1,4-glycosidic bonds from D-glucosamine in one-pot through a combination of two-stage electrolysis and acid-induced isomerization (6 (Figure a.). We will also present the α-selective synthesis of disaccharides containing oxazolidinone protecting groups, which significantly affect the formation of the cyclic structure, and their one-pot synthesis aiming to expand the substrate scope of cyclic oligosaccharides.
We are also conducting research on establishing an electrochemical one-pot synthesis for β-1,6-cyclic oligoglucosamine, in addition to cyclic oligosaccharides containing α-1,4-glycosidic bonds. By introducing different protecting groups to the amino group of glucosamine and its hydroxyl groups, we have achieved control over the cyclic structure and polymerization degree of the products (Figure b.).
1) Varki, A. Glycobiology, 2017, 27, 3.
2) Szejtli, J. Chem. Rev., 1998, 98, 1743.
3) Nokami, T. et al., Chem. Rec., 2021, 21, 2389.
4) Baran, P. S. et al., Chem. Rev., 2017, 117, 13230.
5) Kerns, R. J. et al., J. Am. Chem. Soc., 2001, 123, 9461.
6) Nokami, T. et al., Chem. Commun., 2022, 58, 7948.

Figure 1