bluuebunny/crossref_metadata_2025 huggingface dataset:
A Non-Ideal Transport Model of Bipolar Membranes to Understand and Manage Multi-Ion Interactions in Water Electrolysis
Authors: Galang Francisco Javier Ubongen , Bui Justin C. , Goyal Priyamvada , Weber Adam Z. , Bell Alexis T.
Published: December 2024

Water electrolysis provides a means of producing H2 gas without carbon emissions. However, H2 production through water electrolysis is more costly compared to methods using fossil fuels. A key element to the cost of water electrolysis is the need to purify the water fed to the electrolyzer. Impure feeds can lead to corroding electrodes (e.g. chloride oxidation) and fouling of commonly-used monopolar membranes (i.e., cation and anion exchange membranes). Bipolar Membranes (BPMs), consisting of a cation and anion exchange membranes with a water dissociation catalyst at the interface, pose unique advantages. Because each layer can be tuned independently, BPMs enable higher control of co-ion transport and impurities, unlike monopolar membranes. However, challenges arise in rationally-designing BPMs for impure water electrolysis due to a lack of fundamental understanding of the coupled interactions between water, mobile ions, and fixed charge groups.

In this study, we develop a continuum model to systematically investigate the use of BPMs for water electrolysis with impure feedstocks (e.g. seawater). The model defines the flux of each species using a modified Nernst-Planck-Poisson framework while explicitly considering non-ideal contributions to chemical potential from ion-ion, ion-membrane, swelling, electrostatic, steric, and solvation interactions to the electrochemical potential. The simulations quantify the effect of these interactions and membrane properties on ion transport, and how they could be modulated to mitigate the deleterious effects of impurities and co-ions. Our analysis shows that simple dilute-solution theory is not capable of predicting the effect of impurities on BPM water electrolysis and identifies the dominant interactions that dictate transport in BPMs. This study provides guidelines for modelling water electrolysis and materials design strategies for water electrolysis in non-ideal conditions.
Cellulose-Based Crosslinked and Reinforced Sulfonated Poly(ether ether ketone) Membranes for Robust Proton Exchange Membranes in Fuel Cells
Authors: Lee Dongjun , Kim Daeun , Kim Seungbin , Bae Insung
Published: December 2024

Proton exchange membrane fuel cells (PEMFCs) are a promising clean energy solution due to their high efficiency and eco-friendly operation. Central to their function is the proton exchange membrane (PEM), typically composed of perfluorosulfonic acid (PFSA) ionomers like Nafion and Aquivion. However, challenges such as cost, gas crossover, and limited temperature range persist. To address these, researchers explore hydrocarbon (HC)-based polymers like sulfonated poly(ether ether ketone) (SPEEK), prized for cost-effectiveness and stability. However, HC-based polymers suffer from issues like unstable mechanical behavior and reduced proton conductivity under low humidity, necessitating further development for practical application.

In this study, we propose two approaches to overcome these drawbacks of HC-based PEMs. Firstly, we prepare crosslinked SPEEK membranes with cellulose acetate to enhance proton conduction under low RH conditions and stabilize membrane properties. The crosslinked structure of SPEEK/cellulose membranes is investigated using small-angle X-ray scattering, atomic force microscopy, and transmission electron microscopy. Additionally, we incorporate cellulose-based nanofibers obtained by electrospinning as a reinforcing substrate, enhancing the interaction between the SPEEK matrix and cellulose nanofiber filler. This results in a dense membrane without voids, effectively preventing gas crossover and improving membrane robustness. These investigations using cellulose-containing SPEEK membranes lead to enhanced power density and durable operation of fuel cells, particularly at low RH conditions.
Porphyrin-Based Antioxidant for Proton Exchange Membrane Fuel Cells
Authors: de Wild Tym , Gubler Lorenz , Nauser Thomas , Nemeth Tamas
Published: December 2024

The increase in regulations on per- and polyfluoroalkyl substances (PFAS) due to health and environmental concerns,1 has resulted in an increasing need for alternatives to polyfluoroalkylsulfonic acid (PFSA) based proton exchange membranes (PEMs). An alternate class of polymers are functionalized polyarylenes, such as sulfonated polyphenylenesulfone (sPPS)2, sulfonated phenylated polyphenylenes (sPPP)3, and the co-polymer sulfonated polyphenylene quinquephenylene (SPP-QP)4.

Despite good progress made in reaching comparable performance to Nafion, radical induced degradation of phenyl(sulfonate) rings during fuel cell operation remains prevalent. In a recently published study,5 we investigated the potential of using a Cu(II)-porphyrin complex as an antioxidant for aromatic sulfonate compounds. First, γ-radiolysis was used on aqueous solutions containing the model aromatic compound potassium 4-(tert-butyl)-2-methoxyphenylsulfonate with varying amounts of antioxidant. The exposure of water-based solutions to high-energy radiation results in the formation of hydroxyl radicals, which in turn react with the model compound. Resulting degradation of the compounds was analyzed using high performance liquid chromatography (HPLC). In the second part of the study, we incorporated the Cu(II)-porphyrin into PEMs to test membrane stability during fuel cell operation using an accelerated degradation protocol. The measurements combined with post-mortem analysis show that membranes containing antioxidants have a five-fold increased stability compared to reference non-stabilized membranes.

References:

(1) Ackerman Grunfeld, D.; Gilbert, D.; Hou, J.; Jones, A. M.; Lee, M. J.; Kibbey, T. C. G.; O’Carroll, D. M. Underestimated Burden of Per- and Polyfluoroalkyl Substances in Global Surface Waters and Groundwaters. Nat. Geosci.
2024, 17 (4), 340–346. https://doi.org/10.1038/s41561-024-01402-8.

(2) Araujo, C. C. de; Kreuer, K. D.; Schuster, M.; Portale, G.; Mendil-Jakani, H.; Gebel, G.; Maier, J. Poly(p-Phenylene Sulfone)s with High Ion Exchange Capacity: Ionomers with Unique Microstructural and Transport Features. Phys. Chem. Chem. Phys.
2009, 11 (17), 3305–3312. https://doi.org/10.1039/B822069G.

(3) Adamski, M.; Skalski, T. J. G.; Britton, B.; Peckham, T. J.; Metzler, L.; Holdcroft, S. Highly Stable, Low Gas Crossover, Proton-Conducting Phenylated Polyphenylenes. Angew. Chem. Int. Ed.
2017, 56 (31), 9058–9061. https://doi.org/10.1002/anie.201703916.

(4) Miyake, J.; Taki, R.; Mochizuki, T.; Shimizu, R.; Akiyama, R.; Uchida, M.; Miyatake, K. Design of Flexible Polyphenylene Proton-Conducting Membrane for next-Generation Fuel Cells. Sci. Adv.
2017, 3 (10), eaao0476. https://doi.org/10.1126/sciadv.aao0476.

(5) de Wild, T.; Wurm, J.; Becker, P.; Günther, D.; Nauser, T.; Schmidt, T. J.; Gubler, L.; Nemeth, T. A Nature-Inspired Antioxidant Strategy Based on Porphyrin for Aromatic Hydrocarbon Containing Fuel Cell Membranes**. ChemSusChem
2023, 16 (21), e202300775. https://doi.org/10.1002/cssc.202300775.
Operando Quantification of Dynamic Lithium Active Area Growth in Zero-Excess-Lithium Solid-State Batteries
Authors: Fan Austin , Li Zhuo , Hatzell Kelsey
Published: December 2024

Growing demands for electric vehicles motivate the need for energy-dense battery technologies that can enable enhanced driving ranges on a single charge [1]. Zero-excess-lithium solid-state batteries operate with no excess lithium at the anode, instead fully cycling all the lithium within the cell during each cycle. Removing excess lithium significantly increases the specific and volumetric energy density, improves battery safety, and reduces manufacturing costs [2]. However, zero-excess-lithium solid-state batteries suffer from poor coulombic efficiency and lithium dendrite formation [3] resulting from non-uniform lithium deposition onto the anodic current collector [4]. Optical microscopy is a promising operando technique for examining the electro-chemo-mechanics of lithium nucleation and growth during lithium deposition in a zero-excess-lithium solid-state battery [4]. In this work, we investigate the lithium nucleation and growth behavior on a current collector substrate using a custom cell conducive to operando optical microscopy. The transparent components of the cell allow for direct, real-time observation of lithium plating behavior. In particular, quantifying the dynamic in-plane lithium growth as a function of operating conditions such as current density, temperature, and thermal gradients provides crucial insight into the lithium growth mechanism. Optical data is complemented with mapped synchrotron diffraction data that elucidate the vertical growth of lithium into the solid electrolyte pellet by measuring the relative intensities of lithium. These results enable comprehensive characterization of lithium growth regimes, including in-plane-growth dominant and vertical-growth dominant regimes, at successive capacities of lithium plated. Understanding these lithium growth regimes guides strategies to attain more lateral, uniform lithium deposition, with long-term implications in achieving stable, high-capacity zero-excess-lithium solid-state battery operation.

References:

[1] Yang-Kook Sun. Promising All-Solid-State Batteries for Future Electric Vehicles. ACS Energy Lett.
2020, 5, 3221-3223.

[2] Christian Heubner, Sebastian Maletti, Henry Auer, Juliane Hüttl, Karsten Voigt, Oliver Lohrberg, Kristian Nikolowski, Mareike Partsch, and Alexander Michaelis. From Lithium-Metal toward Anode-Free Solid-State Batteries: Current Developments, Issues, and Challenges. Adv. Func. Mater. 2021, 31(51), 2106608.

[3] Yuan Tian, Yongling An, Chuanliang Wei, Huiyu Jiang, Shenglin Xiong, Jinkui Feng, and Yitai Qian. Recently advances and perspectives of anode-free rechargeable batteries. Nano Energy. 2020, 78, 105344.

[4] Eric Kazyak, Michael J. Wang, Kiwoong Lee, Srinivas Yadavalli, Adrian J. Sanchez, M.D. Thouless, Jeff Sakamoto, and Neil P. Dasgupta. Understanding the electro-chemo-mechanics of Li plating in anode-free solid-state batteries with operando 3D microscopy. Matter. 2022, 5(11), 3912-3934.
(Invited) Treated Perfluorosulfonic Acid Ionomer Layer with Dual Oxygen Transport Pathways for PEMFC Cathode Catalyst Layer
Authors: Nguyen Trung Van , Li Yuanchao
Published: December 2024

A hydrophobic treatment was developed to reduce the liquid water saturation level and increase its removal rate from the cathode catalyst layer (CL) of a PEM fuel cell with the expected outcome to be higher performance in the transport-controlled region. However, test results show improvement (> 200% increase in peak power)[1] in both kinetic and transport-controlled regions. Further investigation by mathematical modeling and neutron reflectometry shows the treatment affects the CL in two ways. First, the ionomer/gas phase interface in the pores of the CL becomes more hydrophobic. This facilitates less liquid water coverage of the ionomer layer surface and faster water drainage from the CL that results in better performance at high current densities, which is as expected. Second, it affects the microstructures of the ionomer phase and causes it to separate into two regions, a larger more hydrophobic (or less hydrophilic) region with fewer sulfonic acid groups and therefore lower water hydration levels and a smaller less hydrophobic (or more hydrophilic) region with more ionic groups with higher hydration levels. The more hydrophobic region, which facilitates faster liquid water removal from its interface with the gas pores and direct access to the oxygen gas at higher current densities, provides a higher oxygen solubility pathway to the catalyst active sites in CL at both low and high current densities leading to higher fuel cell performance over the whole polarization curve. See image. The ratio of these two regions can be controlled by the treatment process. This presentation will discuss the hydrophobic treatment process and the major findings of this study.

References

Regis P. Dowd, Yuanchao Li, Trung Van Nguyen, “Controlling the Ionic Polymer/Gas Interface Property of a PEM Fuel Cell Catalyst Layer During Membrane Electrode Assembly Fabrication,” Appl. Electrochem., 50 (10) 993-1006 (2020).

Yuanchao Li and Trung Van Nguyen, “A One-Dimensional Model of the Cathode Catalyst Layer of a PEM Fuel cell Hydrophobically Treated for Water Management,” J. Electrochemical Society, 169 114505 (2022).

Figure 1
Polymer Additives for the Fabrication of Defect-Free Direct Membrane Fuel Cell Catalyst Layer Coatings
Authors: Baez-Cotto Carlos , Berry Isabelle , Van Cleve Tim , Young Erica , Hu Leiming , Taylor Audrey K. , Gautam Sakshi , Intia Fry , Perales Luis , Ahmed Rafiq , Torres Kevin , Neyerlin K.C.
Published: December 2024

Direct deposition of fuel cell catalyst layers onto membranes is an appealing fabrication approach by virtue of its lower contact resistance compared to traditional coatings onto a gas diffusion media. However, it remains a challenge to produce defect-free catalyst layers, especially in single layer coating processes relevant to roll-to-roll manufacturing (e.g., Mayer rod and doctor blade coating). While the membrane may swell by absorbing the solvents in the ink, the catalyst layer thickness could potentially induce cracks in the resulting electrode. The lack of uniformity and morphological defects that arise from these competing factors can lead to performance loss and early membrane electrode assembly failure. As a solution to these problems, we explored the impact of polymer additives on direct membrane coating (DMC) quality. Incorporation of additives to a pre-mixed catalyst ink enhanced fracture resistance and reduced propensity to swelling in rod-coated DMCs with Pt loadings of ~0.2 mgPt/cm2. Beginning-of-life performance in a 50 cm2 active area closely resembles plots reported for ultrasonic spray coated membranes. Accelerated stress tests and short stack degradation tests reveal that additives can mitigate defects without compromising the long-term durability of these electrodes.
Deep Learning to Automate Imaging-Based Analyses of Polymer Electrolyte Fuel Cells
Authors: Colliard Granero André , Eikerling Michael , Malek Kourosh , Eslamibidgoli Mohammad J.
Published: December 2024

Seamless integration of deep learning and computer vision is accelerating research that addresses the global energy challenge. This is particularly true in the field of renewable electrochemical energy devices, where much-needed progress hinges on the availability of high throughput characterization and the rapid and reliable analytics of large data volumes. The presentation will explore three different use-cases related to autonomous image analysis of polymer electrolyte membrane technologies across nano-, micro-, and macro-scales, aimed at accelerating and enhancing insights in this domain. For each case, a tool was developed that integrates image preprocessing, deep learning-based model prediction, feature extraction, and visualization of results.

At the nanoscale, we have developed a tool for the autonomous analysis of 2D Transmission Electron Microscopy (TEM) images to assess the size and shape of Platinum nanoparticles supported on carbon, the key ingredients in catalyst layers of polymer electrolyte fuel cells [1]. Progressing to the microscale, we will introduce a deep learning-based approach for analyzing micro-CT 3D volumes, focusing on the analysis of pores. This software is designed to perform multi-class segmentation of pores and liquid channels within gas diffusion layers (GDL), providing detailed insights into pore structures and water transport properties.[2] Lastly, at the macroscale, we showcase a tool developed for detecting oxygen bubbles in optical videos from polymer electrolyte water electrolyzers (PEWE). This application enables the time-resolved analysis of bubble dynamics within the flow field of the device, offering a macroscopic view of gas evolution and its impact on device performance.[3] Through these tools, our work demonstrates the potential of deep learning and computer vision to bridge the gap between scales in energy materials research, offering novel insights and expediting the analysis process.

[1] André Colliard-Granero et al., “Deep learning for the automation of particle analysis in catalyst layers for polymer electrolyte fuel cells,” Nanoscale, 2022, vol. 14, no. 1, pp. 10–18.

[2] André Colliard-Granero et al., “Deep Learning for Automation of 3D Pore Analysis in Micro-CT Tomographs,” under preparation.

[3] André Colliard-Granero et al., “Deep Learning-Enhanced Characterization of Bubble Dynamics in Proton Exchange Membrane Water Electrolyzers,” Physical Chemistry Chemical Physics, 2024, Accepted Manuscript. DOI: https://doi.org/10.1039/D3CP05869G
Laboratory-Scale X-Ray Absorption Spectroscopy for in Situ Analysis of Li+-Insertion Mechanisms in Vanadium Ferrites
Authors: Long Jeffrey W. , DeBlock Ryan H. , Ford Hunter O. , Rolison Debra R. , Johannes Michelle D.
Published: December 2024

Vanadium–iron oxides (VFe2Ox) exhibit promising Li+-storage properties when expressed in high-surface-area, disordered/defective forms such aerogels.1 We have also shown that the specific capacity for VFe2Ox can be further increased by compositional substitution with minority amounts of electro-inactive cations such as Al3+ and Zr4+.2 To deconvolve the relative contributions of V- and Fe-based redox and the effects of metal substitution, we turn to X-ray absorption spectroscopy (XAS) as performed with a bench-scale instrument. X-ray absorption near-edge spectroscopy (XANES) provides vital element-specific information on electronic properties and metal oxidation state, while extended absorption fine-structure spectroscopy (EXAFS) produces information on local bonding/coordination, even for amorphous/disordered materials. Using pouch cells designed specifically for the bench-scale spectrometer, we collect in situ spectra on VFe2Ox electrodes as they undergo electrochemical cycling between 2.0 and 3.8 V vs Li/Li+ in conventional nonaqueous electrolyte. We show that the first stages of Li+-insertion are accompanied by Fe3+/2+ redox, with V5+/4+ redox becoming active only at lower cell voltages (<2.5 V). Parallel DFT calculations on a representative spinel-type VFe2Ox structure confirms that V incorporates at tetrahedral sites. The combination of Fe/V tetrahedral occupation and vacancy-induced disorder also lowers the overall energy to open an electronic energy gap that establishes the Fe3+/2+-to-V5+/4+ redox sequence during lithiation, in confirmation of experimental XAS findings. The role of additional metal substitution is also assessed by parallel XAS measurements and DFT computation.

1. C. N. Chervin, J. S. Ko, B. W. Miller, L. Dudek, A. N. Mansour, M. D. Donakowski, T. Brintlinger, P. Gogotsi, S. Chattopadhyay, T. Shibata, J. F. Parker, B. P. Hahn, D. R. Rolison, and J. W. Long, J. Mater. Chem. A
3, 12059 (2015).

2. C. N. Chervin, R.H. DeBlock, J. F. Parker, B. M. Hudak, N. L. Skeele, J. S. Ko, D. R. Rolison, and J. W. Long, RSC Adv.
11, 14495 (2021).
Operando X-Ray Absorption Technique (XAS) and Applications for Energy Storage at Synchrotron in Thailand
Authors: Limphirat Wanwisa , Meethong Nonglak , Pattananuwat Prasit , Pornprasertsuk Rojana , Qin Jiaquian , Kheawhom Soorathep
Published: December 2024

A Synchrotron Light Research Institute (SLRI, Public Organization) is a national laboratory. It is located at Nakhon Ratchasima, Thailand. SLRI provides synchrotron light for structural analysis, research, and development. Currently, SLRI has 10 beamlines and 12 end stations for scattering, diffraction, spectroscopy, imaging, and microfabrication techniques. The status of XAS beamlines has 5 end-stations (BL1.1W, 2.2, 5.2, 7.2W and 8). Recently, the Operando-XAS is performed using beamline 2.2 (Time-resolved X-ray Absorption Spectroscopy, TRXAS) which the main optical component is an energy-dispersive monochromator (EDM). Using the energy-dispersive scheme with a position-sensitive detector, the beam size at the sample position can be small and have a fast detection speed in the XAS spectrum. In this presentation, we will summarize the developments of the experimental tools to characterize energy storage materials (e.g. Lithium-ion batteries, Zn-ion batteries, and H2-production process) and give examples of the capability of the instruments via studies of materials performed at the XAS beamlines in Thailand.
Evaluations of Reaction Heterogeneities in Battery Electrodes upon Fast Charging Using Operando Synchrotron Techniques
Authors: Li Tianyi , Wiaderek Kamila
Published: December 2024

Recently, thick electrodes in lithium-ion batteries have drawn extensive attention as they effectively promote cell-level energy density by reducing the fraction of inactive components such as separators and current collectors. However, due to the sluggish electrolyte transport, the spatially non-uniform reaction can easily arise within a thick electrode design. Understanding the heterogeneous reaction and preventing it from happening is therefore critical as it may result in inferior rate performance, fast capacity degradation, and even safety hazards. This study aims to experimentally evaluate the reaction heterogeneities in thick electrodes by employing operando focused beam X-ray diffraction, and diffraction combined with X-ray absorption spectroscopy. We will compare the traditional graphite anode with different electrode designs in coin cell or pouch cell full cells upon 6C fast charging, therefore, quantitatively assessing the degree of reaction along the depth direction in electrodes under operational conditions. A detailed comparison between the experiments and simulations will help us better understand the origin of reaction heterogeneities in electrodes and guide the design of battery materials and structures in the future.
Simultaneous Analysis of Reaction Distribution at LiFePO4 and LiCoO2 Electrodes of Lithium-Ion Batteries
Authors: Katayama Misaki , Kato Kazuo
Published: December 2024

The electrode reaction distribution of lithium-ion batteries is a noteworthy issue for the construction of safe and sustainable storage battery systems. Electrode reactions at composite electrodes are inhomogeneous on the micrometer to millimeter scale due to local differences in electronic and ionic conductivity. There are many reports on the reaction distribution of single electrodes. How the inhomogeneous chemical state distribution generated in the electrode affects the subsequent charge-discharge reaction has not been systematically studied. The purpose of this study is to clarify how the inhomogeneous reaction distribution affects the other electrode. Synchrotron radiation X-rays can be used to observe inhomogeneous states without disassembling the battery. However, because common negative electrode materials are composed of light elements, X-ray absorption fine structure (XAFS) is usually not applicable for in situ observation of the negative electrode of practical batteries. Therefore, in this study, we fabricated a battery by combining a LiFePO4 electrode and a LiCoO2 electrode, which are normally used as positive electrodes, and analyzed the heterogeneous electrode reactions inside the battery for both electrodes simultaneously. Although the battery is not a combination of positive and negative electrodes as used in practice, the distribution of the chemical states of both electrodes can be visualized using X-rays. XAFS experiments using a two-dimensional detector were performed at SPring-8 BL01B1. The chemical state of the LiFePO4 electrode was determined from the Fe K-edge XAFS spectrum, and that of the LiCoO2 electrode was determined from the Co K-edge to create a chemical state map in the electrode. The battery was equipped with a graphite electrode in addition to LiFePO4 and LiCoO2 electrodes for the initial delithiation process. Charging and discharging were repeated with a combination of LiFePO4 and LiCoO2 electrodes to examine the behavior of the reaction distribution and the positional relationship between the reaction distributions of both electrodes. The result that the reaction progressed in the region of the LiCoO2 electrode that overlapped the region where the reaction was progressing at the LiFePO4 electrode clearly indicates that the inhomogeneous reaction at the electrode propagated to the opposite electrode.
In-Situ AFM Analysis of Lithium Dendrite Growth Dynamics and Preferential Formation Sites
Authors: Kim Seonghyun , Cho Yoonhan , Choi Youngwoo , Hong Seungbum
Published: December 2024

Lithium dendrites must be suppressed to enhance the safety and cycle life of lithium metal batteries, necessitating characterization of their growth processes. However, observing the growth dynamics at the same site has been challenging due to difficulties in in-situ imaging.

Here, we utilized in-situ Atomic Force Microscopy (AFM) to observe the growth dynamics of lithium dendrites and their preferential formation sites during charge and discharge cycles at the same location. We noted that during the initial discharge, lithium preferentially strips from the elevated regions of the lithium surface, leading to thinning and porosity, which we identified as a mechanism for dendrite formation. Subsequent charging preferentially plates the thinned and porous areas. During further discharge, stripping primarily occurs where dendrites were previously formed, leading to an expansion of the dendrite formation area. The observed growth dynamics of lithium dendrites and their preferential formation sites provide insights into methods for suppressing dendrite formation. Furthermore, the in-situ AFM method, applied at consistent locations, has broad potential applications across diverse energy materials.
NMR Analysis for Lithium Metal Batteries and Direct Alcohol Fuel Cells
Authors: Han Oc Hee
Published: December 2024

Improving the energy density and safety of the conversion/storage systems such as fuel cells and batteries is essential because the systems have profoundly impacted the modern lifestyles, enhancing the mobility and convenience of portable electronics and electric vehicles. In such systems, electrochemical reactions and dynamics of chemical species play key roles and understanding them is necessary for developing constituent materials with improved performance. In this respect, NMR spectroscopy has advantage to observe specific nuclei with high selectivity and to obtain quantitative information without discrimination over light atoms or disordered structures. Investigation without damaging samples is additional advantage. Herein representative results will be introduced such as the reaction mechanism of direct alcohol fuel cells investigated by in situ & ex situ techniques and detection on degradation/deformation of polymer electrolyte membranes. In addition, the results of postmortem 7Li NMR spectroscopic analyses will be presented: an ordinary magic angle spinning probe was used to evaluate the reversibility of lithium metal electrodes and the behavior of Li+ in the lithium metal batteries.
Origin of Inhomogeneity inside LiFePO4/Graphite
Authors: Kobayashi Yo , Shono Kumi , Matsuda Keisuke , Nakamura Tomoyuki
Published: December 2024

Lithium-ion battery (LIB) consisted of LiFePO4 cathode and Graphite anode (LFP/Gr) is the most promising cell chemistry for stationary application because of relatively low cost, safe and expected long term operation. In such applications, various operation patterns have been proposed and demonstrated for stationary use cases. Among them, in case of Load Frequency Control (LFC), which is mainly operated around at 50% SOC with rapid charge /discharge, LFP/Gr chemistry was not recommended because such middle range operation induced rapid capacity fade1). In case of LFC operation, LFP and Gr must stay two-phase coexisting flat voltage region, inhomogeneous Li+ distribution induced because there is no potential gradient in the two-phase region. Therefore, we will report difference of capacity fade mechanism between narrow (SOC30-70%) and wide (SOC0-100%) SOC operation with various charge/discharge rate. Cycled cells (26650, nominal capacity 3.4 Ah) were disassembled in Ar-filled glove box, and degree of inhomogeneity was confirmed by reassembly of the coin cell from harvested electrode.

Cells operated between SOC30-70% (1C charge / 3C discharge) showed rapid capacity fade and confirmed apparent Li+ gradation inside the electrode by color variation by post-mortem analysis at 100% SOC disassembly. In addition, though cells operated SOC0-100% (1C charge / 3C discharge) showed longer cycle performance than that of narrow range, similar inhomogeneous Li+ gradation was also confirmed after cycle operation. On the other hand, cells operated SOC0-100% at 1C charge / discharge showed stable cycle performance. Therefore, we concluded that such inhomogeneity was induced not only narrow range SOC operation but also induced by the imbalanced charge / discharge test condition. Kato et al. reported intercalation / deintercalation hysteresis in Gr by differential voltage analysis (dV/dQ) with in situ XRD2). Such slight difference of reaction kinetics may induce such inhomogeneous behavior in long term operation. Although the operation condition is inside the recommended operation condition by the supplier, we should take great care to avoid such imbalanced rate operation to minimize the risk of inhomogeneous degradation.

1) Y. Kobayashi et al., Journal of Power Sources, 451, (2020) 227782.

2) H. Kato et al., Journal of Power Sources, 398, (2017) 49-54.
Quantitative Non-Destructive Morphological Characterization of All-Solid-State Batteries
Authors: Huang Chen-Jui , Oh Jin An Sam , Vicencio Marta , Meng Ying Shirley
Published: December 2024

In recent years, all-solid-state batteries (ASSBs) have attracted considerable attention within the scientific community owing to their potential for achieving high energy density, enhanced safety characteristics, and a broader operational temperature window. Specifically, sulfide-based solid-state electrolytes (SSEs) demonstrated the most promising ASSB chemistry with their room-temperature Li+ ionic conductivity comparable or exceeding to that of conventional liquid electrolytes (~10 mS cm-1). Our previous works showcased the superior cyclability of ASSB implementing sulfide-SSEs and carbon-free silicon anode with phenomenal stable cycling for 500 cycles1. Recently, we further demonstrated the scalability of carbon-free Si anode at the pouch cell level with cell capacity reaching 100 mAh under significantly low stacking pressure of 5 MPa2-3, showing promise to accelerate the development and commercialization of ASSBs.

Characterizing ASSBs during and after operation is critical for their further development. Crucially, scaling up ASSBs to pouch-cell level introduces new challenges as characterizing the internal microstructure and morphological evolution at a larger scale becomes difficult and time-consuming. Previous works using destructive focus-ion beam-scanning electron microscope (FIB-SEM) can only visualize several tens of micrometers with long imaging times for 3D reconstruction up to hours. Thus, techniques with larger field of view (FOV) and shorter imaging time are inevitably needed to have a better statistical analysis. This study leverages the non-destructive nature of synchrotron X-ray micro-computed tomography (CT) to visualize the morphology and microstructure of each component within an ASSB pouch cell. Leveraging the large FOV of X-ray micro-CT, up to several millimeters and shorter imaging time, we are able to perform a quantitative analysis of the extracted microstructural information, including porosity, loss of contact, and tortuosity. These findings will provide a broader understanding of the structural evolution in ASSB pouch cells, bridging the gap between lab-level research and application-level production.

Reference:

Tan, D. H. S.; Chen, Y. T.; Yang, H.; Bao, W.; Sreenarayanan, B.; Doux, J. M.; Li, W.; Lu, B.; Ham, S. Y.; Sayahpour, B.; Scharf, J.; Wu, E. A.; Deysher, G.; Han, H. E.; Hah, H. J.; Jeong, H.; Lee, J. B.; Chen, Z.; Meng, Y. S., Carbon-free high-loading silicon anodes enabled by sulfide solid electrolytes. Science
2021,
373(6562), 1494-1499.

Tan, D. H. S.; Meng, Y. S.; Jang, J., Scaling up high-energy-density sulfidic solid-state batteries: A lab-to-pilot perspective. Joule
2022,
6 (8), 1755-1769.

Chen, Y.-T.; Jang, J.; Oh, J. A. S.; Ham, S.-Y.; Yang, H.; Lee, D.-J.; Vicencio, M.; Lee, J. B.; Tan, D. H. S.; Chouchane, M.; Cronk, A.; Song, M.-S.; Yin, Y.; Qian, J.; Chen, Z.; Meng, Y. S., Enabling Uniform and Accurate Control of Cycling Pressure for All-Solid-State Batteries. 2023.
Nanostructured NiMoO4 as an Efficient Electrocatalyst for Oxygen Evolution Reaction
Authors: Rajangam Vinodh , Kalanur Shankara , Pollet Bruno Georges
Published: December 2024

Electrocatalysts derived from earth-abundant transition metals offer a viable alternative to noble metals for water electrolysis, yet they often suffer from poor catalytic behaviour and limited lifespan. In this study, nanostructured nickel molybdate on nickel foam (NiMoO4/NF) were synthesized via a straightforward hydrothermal process at three different durations (6, 12, and 24 h) to assess their oxygen evolution reaction (OER) performance. The electrodes, specifically NiMoO4-6h, NiMoO4-12h, and NiMoO4-24h, demonstrated significant OER activity in 1.0 M KOH solution, achieving overpotentials of 315 mV, 290 mV and 320 mV for respectively. Notably, the NiMoO4-12h electrode showed an exceptional stability, with only a 1.28% activity decrease after 200 hours at a current density of 10 mA cm-2. This study presents a novel approach to enhancing the electrocatalytic efficiency of these catalysts through optimizing their electrical conductivity, active surface sites, and surface reaction dynamics.

Figure 1 (a) LSV curves at 2 mV s-1 and (b) Tafel plot of NiMoO4 catalysts.

Figure 1
Porous Transport Layers and Microporous Layers Prepared By Tapecasting for PEM Water Electrolyzers
Authors: Tucker Mike C , Lau Grace Y. , Gawas Ramchandra , Lee Jason Keonhag , Peng Xiong
Published: December 2024

Proton exchange membrane water electrolyzers (PEMWE) are promising means to produce hydrogen in absence of carbon emissions when powered by renewable energy sources. The PEMWE converts reactant liquid water and electricity into hydrogen and oxygen gases. A porous transport layer (PTL) is placed between the PEMWE anode where oxygen is evolved and the flowfield where oxygen is removed from the cell. PTLs are typically made of titanium due to its stability against the highly corrosive environment in the anode compartment. The PTL is a key component and must provide electrical contact as well as reactant transport to the catalyst layer, while facilitating by-product oxygen gas removal from the catalyst layer to the exhaust. The porosity and pore sizes in the PTL affect both the interfacial contact area with the catalyst layer and the two-phase transport of oxygen and water in the cell. A microporous layer (MPL) can be added to the PTL to optimize contact to the catalyst layer. Therefore, optimizing the PTL/MPL porous morphology to maximize the interfacial contact area with the catalyst layer while providing efficient two-phase transport to minimize mass transport could help to improve the overall efficiency of PEMWEs.

In this study, titanium based PTLs with different pore sizes and pore structures were fabricated using a tape casting method. Three classes of PTLs were prepared: single-layer PTLs; bilayer MPL/PTLs; and, phase inversion structures with large aligned through-plane pores. In each case, the fabrication process (tapescasting and sintering parameters) and pore structure (Ti and poreformer particle sizes, pore loading) are optimized for PEMWE performance and mechanical integrity. Performance greatly exceeding the commercial sinter- or fiber-based structures is achieved. X-ray computed tomography (XCT) was used to characterize the structure and porosity of the sintered titanium powder-based PTLs. Calculated values of porosity, tortuosity, and permeability are used to inform analysis of the PTL structure impact on performance. This study will provide guidelines for fabricating high-performance PTLs that surpass current commercially-available materials.
Leveraging Machine Learning and Data Mining for Enhanced PEM-Electrolysis Using Standardized Data Management
Authors: Zimmer Stephan , Wiesner Florian , Steiger Jannis , Keller Robert , Wessling Matthias
Published: December 2024

Green Hydrogen production by water electrolysis is paramount in the transition from fossil fuels towards a carbon neutral industry. Hydrogen is expected to function as energy carrier in mobility, energy storage medium in electricity grids and as regenerative fuel in industrial processes such as steel production. Proton exchange membrane water electrolysis (PEMWE) stands out as a promising technology for hydrogen production due to high current densities with high efficiencies and highly dynamic operation. While the number of publications on the production of PEM electrolysers grows steadily, a lack of standardized methodologies and experimental guidelines persists. Many studies focus on specific components and their manufacturing steps, hindering direct comparison and complicating data interpretation. Consequently, standardization of research data and specification of parameters is the objective of the current research landscape.

In this work, we systematically analyzed literature and gathered meta data regarding experimental procedures for lab-scale production of PEM electrolysers. Thereby, special attention is on the identification of potential improvement in data management. The production of electrolysers can be divided into the various tasks as the fabrication of membrane electrode assemblies (MEAs), which includes catalyst ink production, coating and assembly, electrolyser design and characterization. All areas are in turn subdivided into metadata, for example the ionomer to catalyst ratio and catalyst content for the catalyst ink, the coating technology such as spray or slot coating for the coating. In total, over 60 different parameters were considered and a database with over 600 different samples from publications around the world was created. Incomplete datasets were determined by classification using various methods, such as k-nearest-neighbors.

The extensive database was implemented in various machine learning algorithms with the goal of identifying parameters with a significant influence on the target variable based on the polarization curve. We then identify correlations between different parameters and formulate guidelines for individual fabrication steps and materials for electrolyzers. An optimization is then applied to determine the most favorable procedure for MEA fabrication and assembling electrolysers, incorporating all the parameters from the database.

This work lays the foundation for future publications regarding the standardization of research data and shows how correlations between different parameters can be identified and optimized with the help of data management.
An Advanced Allen-Cahn Navier-Stokes Coupled Lbm Model to Predict Two-Phase Flow Dynamics at the Pore-Scale inside a Polymer Electrolyte Water Electrolyzer
Authors: Roy Anirban , Roenning Frida H , Weng Yu-Kai , Aaron Douglas S , Wrubel Jacob A , Mench Matthew M
Published: December 2024

Polymer Electrolyte Water Electrolyzers (PEWEs) stand as promising energy storage solutions, leveraging variable renewable energy sources to produce hydrogen. Simulating the intricate two-phase fluid dynamics within these systems necessitates the use of complex numerical models since direct experimentation to capture these dynamics is difficult. Currently, most models adopt a macroscopic continuum approach. However, integrating various modeling scales, especially coupling two-phase flow interactions between channels and the porous media within such systems, remains challenging1.

This works attempts to address the challenge by developing an advanced Allen-Cahn Navier-Stokes (AC-NS) coupled Lattice Boltzmann Method (LBM) model. Unlike traditional diffuse-interface LBM models based on the Shan-Chen model2, the AC-NS approach demonstrates enhanced stability and accuracy, with minimal parasitic velocities at fluid interfaces. By implementing Allen-Cahn formulation to minimize the free-surface energy of the fluid interfaces3,4, this work showcases the ease of coupling a phase-field (to capture both liquid and gas phase interactions) with the incompressible Navier-Stokes equations using a LBM framework. This highlights the model’s efficacy in predicting the flow dynamics for binary fluid systems with high density and viscosity ratios within porous media (as shown in Figure 1) at relatively low computational costs.

Furthermore, such a model emphasizes the advantage of incorporating natural boundary conditions and using physical parameters such as surface tension and contact angles, tailored to fluid and geometric properties. Lastly, a methodology to integrate the pore-scale model with existing macroscopic continuum scale models will be presented. Such a framework is essential to accurately calculate the mass transport limitations within PEWEs and predict the performance of a PEWE5,6. Therefore, this work achieves a major step towards enhancing the predictive capabilities of numerical models in advancing the design and optimization of PEWE systems.

References:

B. Xu et al., Energy Rev., 3, 100073 (2024) https://doi.org/10.1016/j.enrev.2024.100073.

X. Shan and H. Chen, Phys. Rev. E, 47, 1815–1819 (1993) https://link.aps.org/doi/10.1103/PhysRevE.47.1815.

M. Geier, A. Fakhari, and T. Lee, Phys. Rev. E, 91, 063309 (2015) https://link.aps.org/doi/10.1103/PhysRevE.91.063309.

E. Ezzatneshan and A. A. Khosroabadi, J. Appl. Fluid Mech., 15, 1771–1787 (2022) https://www.jafmonline.net/article_2102.html.

B. Han, J. Mo, Z. Kang, and F. Y. Zhang, Electrochim. Acta, 188, 317–326 (2016).

B. Han et al., Int. J. Hydrogen Energy, 42, 4478–4489 (2017).

Figure 1
Balancing Optimal Hydrogen Evolution and Not Really
Authors: Kim Mansu , Kim Sohui , Hupp Joseph , Whang Dongmok
Published: December 2024

The strategic downsizing of noble metal catalysts is imperative for augmenting atomic utilization efficiency in the realm of sustainable energy applications. Predominantly, strategies have been formulated to robustly immobilize atomically unstable entities, characterized by elevated surface energy, onto substrates replete with structural anomalies and heteroatoms. The conventional impregnation methodology, often deployed for the fabrication of single-atom site catalysts, relies on a reductive approach wherein dilute precursors undergo controlled, sluggish chemical reactions. However, such preparation techniques are fraught with limitations including suboptimal catalyst loading and heterogeneity in particle size and distribution, thereby obfuscating the mechanistic understanding of the catalytic reactions. Furthermore, while heteroatoms within the substrate serve to securely immobilize atomically unstable catalysts, inadvertent alterations in the catalyst's electronic structure, attributed to robust support interactions, further compound the enigmatic interpretation of reaction mechanisms.

This presentation is aimed towards the elucidation of unequivocal mechanistic pathways at the interface during hydrogen production, utilizing structurally well-defined platinum single-atom catalysts. Distinct from their chemically reduced analogs, these platinum single-atom catalysts are synthesized via electrochemical deposition, thereby obviating the necessity for a strongly interactive support medium. Consequently, we present that non-support-interacting, free-platinum atoms will gravitate towards the theoretical upper bounds of hydrogen production efficiency. Additionally, this introduces, for the first time, catalysts comprising exclusively "genuine" single-atom sites, thus poised to illuminate heretofore ambiguous structural attributes associated with contentious single-atom catalytic concepts.
Ink to MEA: Ionomer/Iridium Interactions with Varying Oxide Coverage in Proton-Exchange-Membrane Water Electrolyzers
Authors: Berlinger Sarah A. , Peng Xiong , Kusoglu Ahmet , Crumlin Ethan J. , Weber Adam Z.
Published: December 2024

Proton-exchange-membrane water electrolyzers (PEMWEs) are the state-of-the-art water electrolyzer technology; however, they suffer from high overpotential losses due to the sluggish kinetics of the oxygen evolution reaction on the anode. There have been significant efforts devoted to catalyst engineering to improve the kinetics of OER, often focused on iridium-based materials in acidic environments. Prior work demonstrates the oxide form of iridium significantly affects its activity. Despite this, catalyst-activity benchmarking is often conducted ex situ. Understanding how the ionomer reaction environment in a membrane electrode assembly (MEA) influences catalyst performance is urgently needed.

Here, we investigate the fundamental interactions between ionomer and iridium, how this interaction influences the ionomer structure and behavior, and how this ionomer/catalyst interface mediates MEA performance. We use Nafion as our ionomer, and consider three types of iridium: iridium metal, iridium oxy hydroxide, and iridium oxide. We first conduct investigations into model ink (catalyst and ionomer dispersed in solution) systems using dynamic light scattering and calorimetry. We then fabricate model thin-film systems of ionomer on planar catalysts and measure swelling behavior and structural information via x-ray scattering. We also gain chemical insights into the surface speciation as a function of water content via ambient-pressure x-ray photoelectron spectroscopy. These fundamental efforts inform MEA overpotential analysis as a function of the three forms of Ir and highlight the intricacies of the ionomer/Ir interface.