bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cyclohexanol Proportion Influence on Catalyst Paste Rheological Properties and Screen-Printed Hydrogen PEMFC Electrochemical Performance
Authors: Mendoza Pena Kassim Jose , Fukuda Takeshi , Tsuji Ryuki , Tanabe Maito , Satone Hiroshi , Ito Seigo 
Published: December 2024

Nowadays environmental deterioration and global warming are among the principal concerns for humankind. One of the upstanding technologies to settle them is proton exchange membrane fuel cells (PEMFCs), where through an electrochemical reaction, oxygen and fuel (as hydrogen) are transformed into electric energy, water and heat, usually using carbon supported platinum (Pt/C) as catalyst and Nafion as proton conductive ionomer.
PEMFC production at the laboratory scale is mainly done by spray method, having some counterbacks such as catalyst wasting and slow deposition rate. Recently, the screen print method has caught attention worldwide for industrial-scale production of PEMFC since it was successfully employed in a variety of applications, such as solar cells, microelectronics, etc. This method consists of preparing a catalyst paste dispersing the catalyst with ionomer and solvents, once homogenized the paste is passed through a mesh and then deposited on a substrate in a single quick step avoiding material waste.
For an effective screen print process, a stable and workable catalyst paste is needed, being rheological properties and drying time the most important features to fit those needs. Despite water and low molecular weight alcohols being the typical solvents used for catalyst paste fabrication and the rheological properties of resulting pastes using these solvents are already reported [1], they do not fit the requirements for screen print industrial production.
On the other hand, cyclohexanol has a high viscosity and long drying time, being a promising alternative to obtain a paste suitable for the industry's needs, however, the rheological properties of a catalyst paste containing cyclohexanol remain unclear. In addition, it has been reported that this solvent has positive effects on the catalyst and ionomer interactions, enhancing the catalyst activity and improving mass transport [2].
In this research, several screen print catalyst pastes having the same final volume and different solvent proportions of water, 1 propanol, and cyclohexanol (W:1PA:CHN) were prepared. The same proportion of water and 1 propanol was kept but the proportion of cyclohexanol was gradually increased for each sample: (1:1:0), (1:1:0.5), (1:1:1), (1:1:2) and (1:1:3). Additionally, a sample containing only cyclohexanol was prepared (0,0,1) to discern the isolated effect of this solvent. From the resulting pastes, PEMFC were produced by the screen print method.
The relation between cyclohexanol content and catalyst paste rheological properties was investigated using a cone/plate rheometer, while the screen printed PEMFC electrochemical characteristics by the polarization curve, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), especially for evaluating proton conductivity.
Additives for Improving Chemical Stability of Polymer Electrolyte Membranes
Authors: Shin Dongwon , Kodir Abdul , Lee Hyejin , Bae Byungchan 
Published: December 2024

Polymer electrolyte membrane (PEM) is a key component that affects the performance and durability of various electrochemical devices, including fuel cells and electrolyzers. Despite improvements in PEM performance, durability still needs to be improved. The lifetime of membranes deteriorates under operating conditions due to chemical degradation. This chemical degradation not only reduces electrochemical performance but also its mechanical integrity, ultimately leading to device failure. In recent years, many researches report that durability has been improved by synthesizing chemically stable polymers such as polyphenylenes. In addition, the incorporation of various additives into PEMs has emerged as a promising strategy to enhance chemical stability of membranes. The most commonly used additives to improve the chemical stability of PEMs are antioxidants. Since radicals are mainly generated by hydrogen crossover, additives that can reduce hydrogen crossover can also enhance the chemical stability.
In this study, we investigated the gas barrier properties of several additives and their impact on the performance and durability of PEMs. Gas barrier additives (GBA) were dispersed in polymer solution to form a membrane without phase separation or agglomeration. Composite membranes showed similar water uptake and mechanical properties to the pristine membrane. Although GBAs had excellent gas barrier properties, some of them decreased fuel cell performance. GBA effectively reduced the hydrogen permeation. We down selected GBAs that did not deteriorate fuel cell performance and conducted stability test under open circuit voltage (OCV) conditions. While monitoring OCV, hydrogen permeability and fluoride emission concentration were measured to confirm the degradation tendency of membranes. The durability of the composite membranes was improved compared to the pristine membrane. These results show that not only removing radicals using antioxidants, but also slowing down radical generation by blocking hydrogen crossover is effective in improving the chemical stability of the PEM.
Preparation and evaluation of composite membranes using cellulose nanofibers (CNF)
Authors: Yasuda Tatsuki , Kakinuma Katsuyoshi 
Published: December 2024

Polymer Electrolyte Fuel Cells (PEFCs) have several advantages, such as high efficiency and compactness, and are suitable for residential and mobile applications. The fluorinated polymers (e.g., Nafion) are typically proton-conducting membranes, which are used as the electrolyte of PEFCs under a wide range of humidity conditions, although the operation under low-humidity, high-temperature conditions decrease the proton conductivity due to water evaporation. Nafion membranes that have been prepared by mixing with transition metal oxide nanoparticles have shown higher proton conductivities, reaching values as high as 0.12 S cm-1 (80 ℃, 80% RH)1, 2. The improvement is based upon the increased hydrophilicity of the surface, which helps to maintain the membrane water content even at elevated temperatures. In the present study, we focus on the highly hydrophilic surface of carboxymethyl cellulose nanofibers (CMCNFs) and have investigated the proton conductivity of the composite membranes. The CMCNFs were mixed with Nafion (20 wt.%, DE2020 CS, Chemours) neutralized with potassium hydroxide, and formed into films by use of a die-coater (Taku-dai Mini-50 Daimon Co., Ltd.), with a final hot-pressing (160 ℃, 3 min. TCMD-2.5: TOHO KOGYO Co.). The proton conductivities of the composite membranes obtained were measured by the AC four-probe method. The types of water (chemically bonded, intermediate, and free water) present in the composite membrane were determined by the use of differential scanning calorimetry (DSC).
The composite membranes obtained were flexible and translucent. The proton conductivity of the composite membrane was 1.4 times higher (0.15 S cm-1) than that of a commercial Nafion membrane (NRE211) at 80℃, 80% RH, and was 1.3 times even at 80 ℃, 20% RH. The improved water retention properties achieved by mixing with CMCNF is considered to increase the proton concentration and proton conductivity. DSC measurements showed that bonded water (water that does not freeze down to -55 ℃) remained constant even with variations in the CMCMF content. The intermediate water, with a higher melting point range (melting between -55 ℃ and 0 ℃) increased with increasing CMCMF content. The increase of intermediate water in the composite membrane is considered to contribute to the proton conductivity.
(ECS Edward Goodrich Acheson Award) Improvements in Anion Exchange Membrane Water Electrolysis Materials and Devices
Authors: Kohl Paul , Park Habin , Gerber Hazel , Freer W. Henry , Yang Xiaoxuan , Li Chenyu 
Published: December 2024

Green hydrogen is a critical energy carrier for the future net-zero carbon emission by 2050. Anion exchange polymer electrolytes enable the use earth-abundant catalysts, non-fluorinated solid polymer electrolytes, and low-cost cell components for sustainable, low-temperature water electrolysis to produce green hydrogen. However, long-term durability of the anion exchange membrane water electrolysis (AEMWE) needs to be demonstrated at high current density (i.e., > 1 A/cm2). AEMWE can be operated with a more gentle (i.e., lower) hydroxide anolyte feed for improved chemical durability, however, the cell overpotential has shown to increase at lower pH.
New materials and operating conditions have been demonstrated which contribute to improved durability and energy-efficiency by the use of (i) stable ion conductive polymer membranes, (ii) self-adhesive electrode ionomers, and (ii) a high ionic strength anolyte without raising the pH. The increase in cathode hydration (where water is reduced to hydrogen) is critical to achieving durable, higher current performance. The cathode hydration level was improved in several ways including the use of hydrophilic ion conducting polymer in the membrane and cathode. A self-adhesive poly(norbornene) terpolymer ionomer has been developed for durable electrode fabrication where the hydrophilicity of the electrode environment was adjusted for each electrode. The ionomer was covalently bonded to a catalyst and the gas diffusion layer to achieve stable electrolysis under vigorous gas evolution. The rate of water transport through the AEM was improved by use of a lower pH, higher ionic strength anolyte. It has been shown that increasing the ionic strength of the anolyte, without increasing the pH, assists in water delivery to the cathode. The uptake of alkali cations within the AEM plasticizes the AEM (i.e., increases ion diffusivity) and migration of the hydrated cations to the cathode increases the overall water transport. Finally, improvements in the anion exchange membrane synthesis and fabrication have been found which can lower the overall electrolysis cost. Long-term AEMWE durability with the optimized electrodes and low pH/high ionic strength anolyte is demonstrated.
Performance Improvement of Chemically Durable PVA Gas Barrier PEM by Optimizing the Interlayer Thickness
Authors: Gautama Zulfi , I Yang , Lyth Stephen Matthew , Sasaki Kazunari , Nishihara Masamichi 
Published: December 2024

Polymer electrolyte fuel cell (PEFC) is a portable and clean power source suitable for decarbonizing the transport sector. Recently, PEFC has been developed as a power source for heavy-duty vehicles which requires further improvement on its components, such as the durability of the polymer electrolyte membrane (PEM). One of the challenging issues on PEM is suppression of chemical decomposition of PEM. Several decomposition mechanisms of PEM are proposed like the reactions of crossover oxygen to form hydrogen peroxide (H2O2) at the anode site or deposited platinum in PEM. H2O2 is a starting material of a radical which decomposes the polymer chain of PEM. To mitigate this issue, we have designed a gas barrier PEM which can suppress oxygen penetration through PEM by incorporating a gas barrier polymer layer in between two Nafion layers (Fig. 1a). In a previous study, we loaded 0.5 mg/cm2 of PVA/PVS blend (Fig. 1b) with 100:1 molar ratio as the gas barrier interlayer, which consequently improved the chemical durability by 1.7 times than Nafion under in-situ accelerated stress test (OCV holding test) [1]. However, the fuel cell performance of this gas barrier PEM could only reach 70% of the Nafion’s current density at 0.6 V. To practically use our gas barrier PEM concept as a viable mitigation strategy against chemical decomposition, the fuel cell performance must be improved.
To improve the fuel cell performance of the gas barrier PEM, we focused on optimizing the thickness of the gas barrier interlayer. The interlayer majorly affects the resistance of gas barrier PEMs due to its low proton conductivity. On the other hand, an interlayer with enough thickness is also important to achieve high chemical durability by high gas barrier property. Therefore, we developed thinner gas barrier interlayer with enough high gas barrier property and low resistance. After optimizing the interlayer thickness, we optimized the conditioning procedure for the selected gas barrier PEM to achieve similar catalytic activity with the Nafion MEA.
In this presentation, the effect of interlayer thickness reduction towards fuel cell performance of gas barrier PEM will be discussed in detail. In addition, we also observed that preparation of the gas barrier PEM affected to the MEA performance. Therefore, we optimized the conditioning procedure of the MEA. In this presentation, we selected PVA 0.1 (interlayer loading: 0.1mg/cm2, interlayer thickness: 1 mm, total PEM thickness: 17 mm, PVA: PVS =100:1 (mol)) to have the best balance between fuel cell performance (90% of Nafion’s current density at 0.6 V) (Fig. 1c) and gas barrier property (30% lower hydrogen crossover at 80°C 95% RH). From several results, we confirmed that the PVA 0.1 demonstrated higher chemical durability than Nafion with the same thickness in OCV holding test (Fig. 1d).
References
[1] Gautama, et. al, J. Membrane Science, 2022, 658, 15, 120734.

Figure 1
Transport Properties and Morphology of Cerium Oxide Composite Sulfonated(Poly Arylene Ether Sulfone) Membranes for Application in Heavy-Duty Fuel Cell Vehicles
Authors: Gangavarapu Pranathi , Foister Shane , Goenaga Gabriel , Zawodzinski Thomas A. 
Published: December 2024

Fuel cells for Heavy Duty Vehicles (HDVs) offer easy scalability and the potential for critical reduction in CO2 emissions. During the drive cycles of HDVs, the fuel cells will operate over a range of temperatures, with increases while climbing up steep gradients. Operating temperatures above 90°C will be necessary, along with low relative humidity (RH) due to the need to avoid pressurization of gases. Therefore, Proton Exchange Membranes (PEMs) for HDV applications need to be suitable over this range of conditions, including functioning at high temperatures and low relative humidity. Moreover, the membranes should not swell extensively when more water is present.
In this study, sulfonated poly (arylene ether sulfone) multiblock copolymers were modified with the incorporation of clusters of modified cerium oxide nanoparticles to form composites. These synthesized novel membranes approach operational proton conductivity requirements for HDV vehicles, with conductivity of 15mS/cm at 120°C and 25% relative humidity, remarkably avoiding the typical large decrease in conductivity observed below 70% RH in non-fluorinated PEMs. One purpose of this study is to understand the water, proton, and polymer interactions within these membranes. The cerium nanoparticles and sulfonamide clusters play a critical role in the membrane, affecting conductivity, and water transport, especially at high temperatures and low relative humidity, while also suppressing swelling of the membrane. Membrane proton conductivity is also strongly influenced by physical properties such as water uptake and dimensional swelling behavior, which is further impacted by polymer morphology. To probe the dynamics of the components, the diffusion coefficient and relaxation time of water in the membrane and the protonic conductivity of the membrane as functions of membrane water content are analyzed using nuclear magnetic resonance (NMR) measurements and water uptake measurements. Film property and morphology changes are evaluated using Transmission Electron Microscopy (TEM) and Small-Angle X-ray Scattering (SAXS). This study demonstrates the advantageous and non-linear benefits of closely packed acid clusters with cerium oxide composites on membrane functionality under HDV operating conditions.
Improving the Durability of Perfluorosulfonic Acid Membrane in Pemfcs Using Cerium-Based Radical Scavengers Including Organic Ligand Group
Authors: Lee Byeol-Nim , Cho Hyungkyu , Kim Bonghyun , Lim Jaemuk , Munsur Md Abu Zafar Al , Lim Tae-Hoon , Kim Hyoung-Juhn 
Published: December 2024

Polymer electrolyte membrane fuel cells (PEMFCs) are promising alternative power sources for stationary and automotive applications due to their low exhaust emissions and quick start-up and load response. However, the widespread commercialization of PEMFCs is still challenging to meet the cost and durability. Therefore, enhancing the durability of the PEMFC stack is the most important aspect of recent studies through improving the electrochemical and mechanical stability of major components such as polymer electrolyte membranes (PEM). The main factors contributing to the durability deterioration of PEM are chemical and mechanical degradation caused by the inescapable generation of hydroxyl and hydroperoxyl radical species through gas crossover during PEMFC operation.1 Several studies have proven using the cerium ions as radical scavengers effectively mitigates the chemical degradation of PEMs to solve these problems. Although cerium is an effective radical scavenger, it can be combined with sulfonic acid groups to lower the proton conductivity during cell operation.2

In this study, we aimed to mitigate the polymer electrolyte membrane chemical degradation and minimize proton conductivity deterioration by introducing an organic ligand group to cerium-based radical scavengers. The cerium-based radical scavengers were incorporated into the catalyst ink at different concentrations, and membrane electrode assemblies (MEAs) were subsequently fabricated by spray-coating onto perfluorosulfonic acid membranes using the prepared catalyst inks. The chemical stability of the MEAs including radical scavengers was evaluated by open circuit voltage (OCV) decay and electrochemical gas crossover at high temperatures and with low relative humidity (RH) reactant gases. The fuel cell performance was also conducted using the polarization curve, impedance, cyclic voltammetry, and linear sweep voltammetry at 80 °C and 100% RH conditions. The Cerium-based radical scavenger incorporated PFSA membrane showed significantly extended lifetimes during the steady-state OCV test as compared with a non-stabilized PFSA membrane. The MEA performance tests confirmed that the cerium-based radical scavenger dramatically mitigates degradation effects, which improves MEA chemical durability and minimizes performance losses.
References
[1] M. Zaton et al., Sustainable Energy Fuels 1 (2017) 409–438.
[2] B.P. Pearman et al., J. Power Sources 225 (2013) 75-83.

Figure 1
(Invited) Characterization of Atomic- and Nano-Scale Defects in Ni-Rich Layered Cathode Materials through Neutron and X-Ray Scattering Techniques
Authors: Kim Hyungsub 
Published: December 2024

Ni-rich layered cathode materials have garnered significant attention as promising candidates for Li-ion batteries due to their high energy density. Although extensive research efforts focus on enhancing the structural stability of these materials through elemental doping, surface coating, and the use of electrolyte additives, the intrinsic chemical-mechanical instability caused by atomic- and nano-scale defects during the synthesis process remains a substantial challenge.
Recent studies have focused on improving the cycle life of Ni-rich layered cathodes by fundamentally enhancing Li/O insertion. These enhancements have been achieved by regulating key parameters, including excess-Li content, temperature, and oxygen atmosphere during synthesis, often without the need for additional treatments. Additionally, a pre-calcination stage at 200–500°C is typically employed during synthesis to efficiently decompose the precursor. However, the precise rationale behind Li overloading remains largely unexplored, and comprehensive studies on the impact of the pre-aging process on the crystal structure and morphologies of Ni-rich NCM materials are notably scarce.
In this study, we investigate the atomic- and nano-scale structural evolution of the Ni-rich layered cathode using X-ray/neutron scattering and electron/X-ray microscopy. Our findings reveal that excessive Li can be integrated into the transition metal layer of the layered structure by modulating the Li content and synthesis temperature. We present the first quantification of nanoscale pores in primary and secondary particles of the Ni-rich cathode using small-angle X-ray and neutron scattering analyses. Furthermore, we propose a simplified synthesis route aimed at mitigating the formation of multi-scale defects in Ni-rich layered cathodes, leading to superior electrochemical cycle stability. This research provides crucial insights into defect characterization and management, potentially driving advancements in the design and production of high-performance Ni-rich layered materials.
(Invited) Magnetic Field Imaging for Fault Diagnosis of Lithium-Ion Batteries
Authors: Lee Hongkyung 
Published: December 2024

The popularity of Li-ion batteries for electric vehicles has spotlighted their importance in safety. Nonetheless, they can accidentally fail sometimes due to small, undetectable errors during manufacturing or use. Identifying these flaws and distinguishing between different types of cell failure without physically opening the cell presents a significant challenge. Although minor errors inside the cells can trigger catastrophic failures, tracing them and distinguishing cell failure modes without dissecting the cell remains difficult. Since various defects within the cell could cause abnormal current flow compared to normal cells, visualizing the current inside the battery allows us to pinpoint and track these invisible defects over large-area cells. Focusing on how the current moves inside the battery helps us uncover and address hidden defects, enhancing battery safety and ensuring the reliability of Li-ion batteries.
This talk introduces a real-time, non-invasive magnetic field imaging (MFI) tool capable of detecting the magnetic field signal induced by abnormal current flow inside fault-simulated Li-ion pouch cells. MFI offers high-speed scanning (~100 mm/min) and high spatial resolution (0.161 mm) with the benefits of simple instrumentation and the acquisition of directional information. By validating the Biot-Savart law, normal current flow patterns can be identified through cross-validating simulation studies and experimental results using MFI. To demonstrate the efficacy of current flow pattern analysis in battery fault diagnosis, the MFI study was extended to identify detectable defects among various flaws and to determine if the severity of these defects can be quantified by building experimental and simulational fault-simulated cells. Direct visualization of current distribution patterns and understanding pattern changes during operation is believed to expedite the non-destructive, immediate diagnosis of commercial cells and address safety-related challenges.