bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Critical Factors Inside and Outside Localized Corrosion Sites
Authors: Kelly Robert G
Published: December 2024

All localized corrosion involves the galvanic coupling of the site of the active dissolution inside with the passive surface outside acting as the main cathode. There are critical factors associated with each part of the galvanic couple, as well as with the electrolyte that serves as the required ionic connection between them. To maintain pit stability, the pH and potential at the corroding surface inside the pit must be maintained below and above critical values, respectively. The two parameters are intimately linked to one another and manifest their influence through the dissolution current density which defines the chemical composition of the solution at the pit’s surface. This critical concentration is often described in terms of the fraction of saturation with respect to the chloride salt of the dissolving metals. The critical values of pH, potential, and current density reflect the need to maintain conditions at the rapidly corroding interface that are incompatible with repassivation. Not maintaining this critical condition leads to a cascade of events that result in formation of a nucleus of oxide which further destabilizes the dissolution, resulting in widespread formation of passive oxide in the pit. The conservation of charge requires that any metal dissolution be exactly balanced by a cathodic reaction. The vast majority of that cathodic reaction must occur outside the pit in aqueous solutions to avoid a catastrophic increase in the local pit pH, leading to repassivation. Thus, the kinetics of the cathodic reaction(s) on the outer, passive surface are critical to pit stability. Due to the ionic current between anode and cathode, the conductivity of the solution between the pit and the area outside it can also influence pit stability. Overlaying these critical factors is the geometry of the pit and the electrolyte outside the pit. This talk will review the nature of these critical factors and focus on the connections amongst them.
Digital Twin-Driven Analysis of Microstructure Evolution in Li-Ion Battery Electrodes during Calendering
Authors: Lim Jaejin , Song Jihun , Lee Hyobin , Kim Kyung-Geun , Lee Yong Min
Published: December 2024

As electric vehicles (EVs) have replaced internal combustion engine vehicles (ICEVs), there's a requirement to increase the energy density of lithium-ion batteries (LIBs) to match the mileage capabilities of ICEVs. Achieving this accompanies optimization in the calendering process, which plays a crucial role in designing high-energy-density LIBs under the same materials. A well-designed calendering process not only boosts energy density but also improves the electronic conductivity and mechanical durability of electrodes. However, excessive calendering can result in detrimental effects such as the formation of tortuous ion percolation pathways and mechanical breakdown like crack formation in active materials. This underscores the importance of understanding how calendering impacts the microstructure of composite electrodes, which varies depending on the pressure levels applied. Therefore, a thorough analysis of the effect of the calendering process on composite electrodes is essential. Nonetheless, it is challenging to analyze microstructural changes and correlate them with electrochemical characteristics solely through experimental means.

Addressing this challenge, herein, digital twin 3D structures of composite electrodes were obtained from FIB-SEM tomographic images before and after the calendering process. Subsequently, simulations of the calendering process are conducted to analyze the microstructure evolution depending on the calendering ratio or electrode density. As a result, virtual structures derived from the calendering simulation are created with varying densities. Key parameters related to electrochemical performance are calculated, enabling a systematic analysis of the structural, electrochemical, and mechanical characteristics during the calendering process.
Chemical Durability Enhancement of Gas Barrier Cellulose Nanocrystal Electrolyte Membranes
Authors: Nishihara Masamichi , I Yang , Gautama Zulfi , Lyth Stephen Matthew , Sasaki Kazunari
Published: December 2024

Polymer electrolyte fuel cells (PEFCs) system for fuel cell vehicle (FCV) application is one of promising technologies to reduce carbon dioxide emission from transportation sector and mitigate the global warming issue. However, durability of the PEFC system is not enough for commercial requirement, especially heavy-duty vehicles. With regards to polymer electrolyte membranes (PEMs) in the PEFCs system, chemical degradation is the important issue of PEM durability and occurs because of radical attacks during fuel cell operation. One of the routes of radical formation is related to oxygen penetration from cathode to anode through PEMs (Fig. 1, a)[1]. Based on this mechanism, suppressing gas penetration is one of the solutions to alleviate radical attacks to PEMs. To realize this concept, we developed a high gas barrier sandwiched PEM by introducing a cellulose nanocrystals (CNC) interlayer (Fig.1, b, c). CNCs are an abundant biomaterial and have high gas barrier property. To use the biomaterial with high gas barrier, we confirmed the fuel cell performance and chemical durability of the gas barrier PEM.

A gas barrier CNC interlayer was sandwiched between two Nafion211 outer layers (Fig.1, c), and the total thickness was about 55µm. Fuel cell performance of the CNC gas barrier PEM was evaluated under 80°C and 95% RH. Then, open-circuit voltage (OCV) holding test, accelerated stress test for PEMs, was performed to evaluate the chemical durability of PEMs under 90°C and 30% RH, and the performance of PEMs were also measured after every 72 hours cycle during OCV holding test by following NEDO protocol.

CNC gas barrier PEM could exhibit about 4 times higher gas barrier properties than Nafion211 doble layer (N211DL, 50µm) under 80˚C and dry condition. And the CNC gas barrier PEM could show about 1.6 times longer durability than N211DL in the OCV holding test (Fig. 1, d), indicating that good gas barrier CNC interlayer could suppress radical formation. Therefore, we proved our research concept is available for cellulose nanocrystals, promising for durable PEMs and future PEFCs applications.

References

Gautama, et. al, J. Membrane Science, 2022, 658, 15, 120734.

Figure 1
Interpretation of PEMFC Impedance Response Using Continuum Modeling
Authors: Dizon Arthur , Mukundan Rangachary , Weber Adam Z.
Published: December 2024

The proton-exchange-membrane fuel cell (PEMFC) is an energy conversion technology developed to assist in the decarbonization of our energy infrastructure. Oxygen and hydrogen are electrochemically reacted to produce electricity, which can be used to power industrial processes like transportation and manufacturing. For hydrogen viability in heavy-duty transportation applications, PEMFC stacks are required to operate over long times scales, which prompts the development of more durable PEMFCs. Improving the durability of PEMFCs relies on understanding process variables and parameters that cause degradation and performance loss. A common diagnostic tool for electrochemical characterization is electrochemical impedance spectroscopy (EIS), where the current—potential relationship of an electrochemical cell is probed using sinusoidal perturbations, which yields the transfer function known as impedance.

Due to the complex physics and chemistry occurring within a PEMFC, meaningful interpretation of impedance spectra is often challenging and relies on assumed equivalent-circuit models. The objective of this work is the development of mathematical continuum first-principle cell-level models capable of providing insight on the relationship between cell properties and measured impedance spectra. The mathematical model is based on a non-isothermal multi-scale continuum model of a PEMFC that accounts for multi-phase transport, where the impedance response is simulated about a steady-state operational mode.

The mathematical model was used to simulate experimental measurements obtained from accelerated-stress tests on a commercially available PEMFC membrane-electrode assembly, as shown in Figure 1. Kinetic parameters obtained from a single EIS measurement were generalized to estimate overall cell performance, which was in good agreement with experimental polarization curves. The mathematical model represents the development of descriptive diagnostic tools capable of providing insights into the underlying governing physics and chemistry.

Acknowledgements

This research is supported by DOE Hydrogen and Fuel Cell Technologies Office, through the Million Mile Fuel Cell Truck (M2FCT) Consortia.

Figure 1
Design of Pillar-Structured Electrode of Polymer Electrolyte Fuel Cells by Experiment and Simulation of Reaction and Mass Transport
Authors: Koshiba Hideto , Nagato Keisuke , Inoue Gen , Tomizawa Morio , Tanaka Akihisa , Nakao Masayuki
Published: December 2024

Imparting microstructures into polymer electrolyte membranes is effective in improving the performance of polymer electrolyte fuel cells (PEFCs). A previous study proposed a pillar structure as a microstructure from the viewpoint of proton conductivity [1]. In this study, we focus on the effect of the pillar-structured electrode on the power generation performance. The pillar structure was transferred to the cathode by thermal nanoimprinting using a self-made mold, and the catalyst layer was deposited by air spraying. Four pillar structures with different widths and heights were fabricated. The pillar electrode was then fabricated by hot pressing a gas diffusion layer (GDL) on the cathode and a gas diffusion electrode (GDE) on the anode. The fabricated pillar electrodes were then subjected to Linear Sweep Voltammetry (LSV). Figure 1 shows the polarization curve and power density of MEA, where W is defined as pillar width and H as pillar height. As shown in Figure 1, the power generation performance of the pillar electrode was 40% higher than that of the flat electrode. In addition, the power generation performance was affected significantly by the change in the pillar height and negligibly by the change in the pillar width. In this paper, the effect of the pillar structure is discussed using reaction transport simulations, in addition to experiments.

Reference

[1] M. Tomizawa et al., J. Power Source., 556(2023) 232507.

Figure 1
Determining Electrode Microstructural Parameters with X-Ray Microscopy
Authors: Lowe Jeffrey , Janakiraman Umamaheswari , Less Greg , Kerns Robert , Muyanja Nancy
Published: December 2024

The transportation industry is in the midst of a transition to electric vehicles (EVs). In order to drive the mass adoption of EVs by consumers, technology advancements are needed. Significant barriers to vehicle performance stem from limitations in battery cell electrochemistry. In particular, a lack of understanding of electrode-level volume change during battery charging/discharging contributes to unclear design parameters at the battery pack level. In this work, we present a methodology to quantify electrode-level thickness changes during cycling using X-ray imaging, a non-destructive technique. This approach provides the ability to track thickness change during cycling without sacrificing the cell. Additionally, we show a method to compute porosities and tortuosities of layered transition metal oxide cathode materials with high-resolution X-ray imaging. These parameters are key inputs to physics-based models employing porous electrode theory. In sum, this work can be used to optimize pack design and to speed up virtualization efforts to more rapidly screen promising cell chemistries for future vehicle technologies.
Multilayer Porous Transport Layers for Polymer Electrolyte Water Electrolysis to Replace Thin Protective Pt Coating at Low IrO2 Loading
Authors: Turtayeva Zarina , Weber Carl Cesar , Herranz Juan , Buechi Felix N.
Published: December 2024

The use of expensive PGM catalysts for the OER and HER leads to high production costs of Polymer electrolyte water electrolysis (PEWE). Moving towards lower iridium oxide (IrOx) catalyst loadings for the anode side can severely affect performance and stability [1]. Recent studies revealed that the structure of the interface between the anodic porous transport layer (PTL) and the catalyst layer (CL) is a crucial factor limiting cell efficiency and contributes significantly to the performance and use of the CL. The coarse structure PTL can develop inactive zones of the catalyst layer, which happens when the catalyst layer is not “close” to the connecting titanium structure [2]. The situation becomes worse when the IrO2 catalyst loading is reduced, and the catalyst layers become thinner. Recent evidence has shown that having additional Microporous layers (MPL) can overcome some of these issues by maximizing catalyst utilization and increasing cell efficiency. However, at low Ir loadings, a thin protective Pt coating on MPL is needed to avoid formation of TiOx passivation layer on the MPL surface and increase surface conductivity [3].

In this work, we attempt to replace the thin protective Pt coating by adding an additional layer of Ti or TiN on the existing MPL aiming when using low loadings of IrO2 (0.5 – 0.1 mgIr cm-2). Vacuum plasma spraying (VPS) technology was used to apply TiN on the surface of MPL, while Ti was spray-coated, and vacuum sintered to create a hierarchically structured 3-layer PTL. Electrochemical performances of both Ti and TiN coated MPLs were evaluated by polarization curves and Electrochemical Impedance Spectroscopy measurements. The results are compared with a Pt coated MPL reference.

References:

[1] M. Yasutake, D. Kawachino, Z. Noda, al -, E.M. Bernt, C. Schramm, J. Schröter, S.M. Alia, K.S. Reeves, J.S. Baxter, Analysis of Voltage Losses in PEM Water Electrolyzers with Low Platinum Group Metal Loadings, J. Electrochem. Soc. 165 (2018) F305. https://doi.org/10.1149/2.0641805JES.

[2] T. Schuler, J.M. Ciccone, B. Krentscher, F. Marone, C. Peter, T.J. Schmidt, F.N. Büchi, Hierarchically Structured Porous Transport Layers for Polymer Electrolyte Water Electrolysis, Adv. Energy Mater. 10 (2020) 1–12. https://doi.org/10.1002/aenm.201903216.

[3] C.C. Weber, S. De Angelis, R. Meinert, C. Appel, M. Holler, M. Guizar-Sicairos, L. Gubler, F.N. Büchi, Microporous transport layers facilitating low iridium loadings in polymer electrolyte water electrolysis, EES Catal. 2 (2024) 585–602. https://doi.org/10.1039/d3ey00279a.
Techno-Economic Analyses on Electric Ship By NH3 Fueled Solid Oxide Fuel Cells
Authors: Horita Teruhisa , Bagarinao Katherine Develos , Kishimoto Haruo , Matsui Toshiaki , Muroyama Hiroki , Kakinuma Yasuo , Sumi Hiroshi , Adam Paul , Rothe Stefan , Megel Stefan , Kusnezoff Mihails , Hartmann Mark , von Einstedel Julius
Published: December 2024

We have been conducting an international collaboration study on “Green ammonia synthesis and utilization by solid electrolysis cells for maritime application” between Germany and Japan (term 2022-2024) under the SICORP program of the Japan Science and Technology Agency (JST). The contributors of this project are AIST, Kyoto University, and Morimura SOFC Technology from the Japanese side and Fraunhofer IKTS and EDL from the German side.

The purpose of this project is to establish a new concept for an energy loop based on ammonia synthesis and utilization with maritime applications. One of the work packages of this project is to evaluate the feasibility of electric ships by using Solid Oxide Fuel Cells (SOFCs) with ammonia fuels. The important point of this project is to give a concept for such NH3-fuel SOFC ships based on techno-economic evaluation.

As a preliminary evaluation of this concept, we have started the feasibility study on the SOFC system based on the literature data so far. A 200 kW SOFC system is considered for a small boat (less than 100 ton class) with an NH3 tank. Const evaluation and technical barriers are presented, and the technical target will be presented to achieve the realization of such a ship.

Figure 1
Insights into Crystallography and Electrochemical Performance of Doped Li-Rich Layered Oxides for Lithium-Ion Batteries
Authors: Celeste Arcangelo , Silvestri Laura , Brutti Sergio
Published: December 2024

The development of new materials is imperative to meet the growing demand for systems delivering higher capacity, energy density, cycle life stability, and safety. Lithium-Rich Layered Oxides (LRLOs) are at the forefront of enabling high-capacity and high energy density positive electrodes for Lithium-Ion Batteries, addressing the challenges of green and safe transportation and sustainable stationary energy storage from renewable sources [1]. LRLOs, with the general formula Li1+xTM1-xO2 (where TM represents a blend of transition metals such as Mn, Co, Ni...), belong to the layered material family but their crystal structure remains elusive [2]. On the other hand, they exhibit excellent reversible performance in aprotic lithium-metal and lithium-ion batteries over numerous charge/discharge cycles. Their higher specific capacity compared to commercial cathodes can be attributed to cumulative cationic and anionic redox processes, wherein anionic redox reactions involve lattice oxygen, balancing lithium extraction with the activation of the O2-/O- redox couple. However, inadequate cycle life stability and capacity retention hinder their commercial adoption, owing to structural rearrangements and phase transitions upon cycling. Moreover, reducing costs and toxicity of raw materials such as cobalt is crucial for large-scale production [3].

In this communication, we elucidate the significant influence of extensive defectivity on the description of LRLOs crystal structure. Specifically, we illustrate how the utilization of supercells or defects (antisite defects, stacking faults ...) contribute to a more accurate structural description. Additionally, doping strategies were used to enhance the electrochemical behavior and mitigate the structural rearrangements. Our findings showcase optimized layered materials boasting exceptional electrochemical performance, enhanced environmental compatibility, and reduced manufacturing costs relative to the current state-of-the-art.

References

[1] S. Zhao, Z. Guo, K. Yan, S. Wan, F. He, B. Sun, G. Wang, Energy Storage Mater
2021, 34, 716–734.

[2] A. Celeste, M. Tuccillo, A. S. Menon, W. Brant, D. Brandell, V. Pellegrini, R. Brescia, L. Silvestri, S. Brutti, Small Methods
2024, DOI 10.1002/smtd.202301466.

[3] A. Celeste, F. Girardi, L. Gigli, V. Pellegrini, L. Silvestri, S. Brutti, Electrochim Acta
2022, 428, DOI 10.1016/j.electacta.2022.140737.
The Effects of the Binder’s Surface Free Energy on the Properties of Aqueously Processed LNMO Cathodes
Authors: Weber Andreas , Bauer Werner
Published: December 2024

Herein we investigate the influence of surface free energy (SFE) on the processing and the resulting properties of water-based LNMO cathodes using a blend of PVDF latex and CMC. Starting with the examination of surface free energy through Sessile Drop and Washburn method the interaction or lack thereof between the different components inside the aqueous slurries can be explained. Four different PVDF latices were applied with particular focus on their SFE. The influence of surface free energy was investigated with regard to adhesion strength, interface resistance, bulk resistivity and water retention of the cathodes. The electrochemical performance (rate capability and long-term capacity retention over 1000 cycles) of the different cathode compositions was compared in full-cell configuration. The electrodes were subsequently analyzed post-mortem by EDS analysis.
Nearly All-Active-Material Disordered Rock-Salt Cathodes for Ni- and Co-Free Li-Ion Batteries
Authors: Lee Jinhyuk , Seo Dong-Hwa , Lee Eunryeol , Lee Dae-Hyung
Published: December 2024

The global shift towards electric vehicles and large-scale energy storage systems necessitates cost-effective and abundant alternatives to commercial Co/Ni-based cathodes, such as LiNi0.6Mn0.2Co0.2O2, for Li-ion batteries (LIBs). Manganese-based disordered rock-salts (Mn-DRXs) have shown promising potential to outperform conventional cathodes at a lower cost, achieving energy densities exceeding 900 Wh kg-AM (per active material, AM).[1-4] However, previous demonstrations of such performance have been conducted in cell constructions that are far from commercially viable, utilizing diluted electrode films (∼70 wt%-AM) containing excessive carbon and binder.[3]

In this presentation, I will address the challenges associated with attaining AM-concentrated Mn-DRX cathodes (>95 wt%-AM).[5] It will be revealed that the failures observed in AM-concentrated electrodes of Mn-DRXs stem from their remarkably low electrical conductivity (ranging from 10−10 to 10−8 S/cm) and the subsequent collapse of the electrode's electrical network due to volume changes over cycling. I will then outline strategies to mitigate these challenges through electrical percolation engineering and the enhancement of electrode mechanical properties. Through these approaches, we have successfully demonstrated nearly all-AM Mn-DRX cathodes (∼96 wt%-AM) and achieved the highest application-level energy density (∼1050 Wh kg-cathode) reported to date.[5]

Furthermore, I will discuss the trade-off associated with the manganese content in Mn-DRXs concerning their electrical conductivity and volume change behavior. This discussion will provide valuable insights and guidelines for material design aimed at advancing Co/Ni-free LIBs' technology readiness.

Overall, this presentation will shed light on the current status, challenges, and breakthroughs in the development of Mn-DRX cathodes, offering a pathway towards more efficient and sustainable LIB technology.

References

J. Lee et al., Science 343, 519−522 (2014).

J. Lee et al., Nature 556, 185–190 (2018).

H. Li, R. Fong, D.-H. Seo, J. Lee et al., Joule 6, 53–91 (2022).

E. Lee, H. Lee, J. Lee, D.-H. Seo et al., Adv. Mater. 35, 2208423 (2023).

E. Lee, D.-H. Lee, D.-H. Seo, J. Lee et al., Energy Environ. Sci. (2024) https://doi.org/10.1039/D4EE00551A.
Electronic Conduction Path Design in the Lithium-Ion Battery Electrodes Using Electrostatic Dry Coating Process
Authors: Yonaga Ayaka , Kawauchi Shigehiro , Kawaura Hiroyuki , Isegawa Kazuhisa , Kimura Hidehiko , Matsunaga Takuro , Nakamura Hiroshi
Published: December 2024

With the further spread of electric vehicles, lithium-ion batteries (LiBs) are required not only to improve battery performance but also to reduce manufacturing costs and CO2 emissions. Generally, the LiB electrodes are made by using slurry wet coating process, which involves solvent drying and recovery steps. There are problems such as high production costs and high CO2 emissions. As one means of solving these problems, solvent-free dry coating process is attracting attention. In addition, from the viewpoint of improvements in battery performance, the LiB electrodes have become thick to enhance the energy density of LiBs. However, thickening the electrodes substantially lengthens the ionic and electronic conduction paths within the electrode, leading to a substantial decrease in battery capacity. In this study, a dry coating process using an electrostatic field was investigated to improve both battery performance and productivity of the electrode manufacturing process. The electrostatic field was used for powder deposition (electrostatic printing) and particle orientation control. Particle orientation was particularly targeted at anisotropic conductive additives, and methods to orient them in the electrode thickness direction to form electronic conduction paths were investigated. Carbon fiber (fiber diameter: 11 μm, fiber: 70 μm) was added as a conductive additive and applied on the current-collector foil by electrostatic coating method together with other materials (active material, acetylene black, and binder) to orient the carbon fiber in the film thickness direction. To identify the process parameters for controlling the orientation of carbon fibers, we conducted orientation analysis of carbon fibers within the electrode using the three-dimensional structure obtained from X-ray computed tomography (CT). Furthermore, we investigated the effect of adding carbon fibers in the electrode and controlling orientation of them on battery performance through electrochemical evaluations. In this presentation, we will discuss in more detail the method of orientation control of carbon fibers using the electrostatic dry coating process, as well as the results analyzing the effects of adding and orientating carbon fibers on battery performance.
Concomitant Optimization of Lithium Diffusion and Conductivity during Crystallization of TiNb2O7 Mesoporous Microparticles
Authors: Sturgill Christopher James , Wechsler Sean Cade , Stefik Morgan
Published: December 2024

The demand for fast-charging electric vehicles requires a combination of the right materials with the right morphologies. TiNb2O7 (TNO) is a material that combines rapid ionic diffusivity with a stable framework for repeated cycling given its Wadsley-Roth crystal structure. The capabilities of a battery rely heavily on contributions from the material such as lithium diffusivity and electrical resistivity, along with aspects of the material’s architecture like feature size and porosity. Here, the synthetic processing of each electrode influences its charging performance by determining the crystal structure, defects, and morphology simultaneously. Spray dried TNO was crystallized over a range of temperatures from 600-1100°C. The crystallization and architectural coarsening were examined with a range of techniques including X-ray methods (SAXS and WAXS) and electron microscopy (SEM). Standard galvanostatic cycling was used to assess C-rate capacity where the samples treated between 700-1100°C had similar capacities at low C-rates of 0.1C (~300 mAh/g), but sample TNO-800 was uniquely able to exhibit a capacity of 260 ± 3 mAh/g at a higher C-rate of 5C. Intermittent current interruption measurements enabled the determination of ion diffusivity, internal resistance, and diffusion resistance. Lithium diffusivity consistently increased with increasing crystallization temperature whilst changes in electronic resistance were more complex with a minimum resistance for TNO-800, attributed to crystalline defects. The combined optimum of ionic and electronic transport enabled the highest performance for TNO-800 at 10C with a capacity of 233 ± 1 mAh/g that surpasses most TNO precedents. This study spotlights the convolved evolution of crystal/defect structures simultaneously with architecture changes during crystallization and is a possible path forward to improve other battery materials.
Comparison of Characterization of High Nickel Single Crystal Cathode Materials According to Pre-Heating and Reheating Temperature
Authors: Yun Ye Ji , Sung Ye Jin , OH Eun-Suok
Published: December 2024

A high-nickel cathode with high reversibility Li[NixCoyMn1–x-y]O2 (x ≥ 0.6) is one of the most commonly used cathode materials in lithium-ion batteries. However, as the nickel content increases, the instability of the layered structure of the cathode increases, which adversely affects the life performance. In addition, such a high-nickel polycrystalline cathode material causes cracks in particles during pressing or charging and discharging, ultimately leading to the deterioration of cycle performance. To solve this problem, a single crystal cathode material synthesized at 900 Celsius degrees or higher has been proposed. However, research on specific temperature conditions of a high-nickel single crystal cathode is insufficient. In this study, a method of synthesizing LiNi0.8Co0.1Mn0.1O2 (NCM811) high-nickel single crystal cathode is presented, and the physical characterization and electrochemical performance of the cathode material are compared according to the pre-heating temperatures and the reheating temperatures.

Keywords: Lithium-ion battery, Cathode material, single crystal cathode’s calcination temperature, LiNi0.8Co0.1Mn0.1O2

Figure 1
Rapid Scalable Plasma Processing of Lithium Lanthanum Zirconium Oxide (LLZO) Separators for Solid State Batteries
Authors: Crane Gabriel Badillo , Holmes Sarah , Colburn Thomas William , Barrera Francisco , Cui Yi , Dauskardt Reinhold Horst
Published: December 2024

Metal oxide based solid state batteries have proven to be a hot topic in the search for next-generation battery materials, with materials such as Lithium Lanthanum Zirconium Oxide (LLZO) taking the spotlight for their promise of improved safety, reduced flammability, and stability against lithium-based anodes. However, there are still outstanding challenges in repeatably creating low-defectivity thin films at thicknesses thin enough to function as effective battery separators, as well as preventing the loss of lithium due to high-temperature sintering. Furthermore, much of the research on the synthesis of such materials uses expensive or lab-scale methods such as spin coating or magnetron sputtering, meaning these syntheses will require significant changes in implementation to allow for the jump to materials production for large-scale applications such as grid scale energy or electric vehicles.

We present here an alternative approach for the synthesis of aLLZO thin films using an ambient pressure, low temperature nitrogen plasma curing to rapidly and repeatably produce lithium-containing metal oxide thin films with negligible loss of lithium. The films are rapidly processed in-line with a sub-5-minute plasma curing step (an order of magnitude improvement over conventional methods) using a dry-air ambient-pressure environment. The multiple energy sources inherent in the plasma, including radical ions, UV light, and heat, allow for a low processing temperature of less than 300°C. We demonstrate that we have obtained a high aLLZO conductivity of 2E-6 S/cm at room temperature, which improves to 1E-3 S/cm at the expected operating temperature for electric vehicles (typically on the order of 95-100°C). XRD and XPS analysis demonstrate a uniformly amorphous phase with the expected elemental stoichiometry, with negligible lithium loss. SEM and AFM analysis show a smooth morphology with <40 nm roughness. This novel synthetic approach opens the door to scalable manufacturing of next generation metal oxide battery separators.
Enhancing Solar Chemical Conversion Performance through Underlayer Modification on Copper-Based Mixed Oxide Films
Authors: Choi Seungyo , Kim Kitae , Kim Tae Woo , Park Hyunwoong
Published: December 2024

This study focuses on synthesizing copper-based delafossite films through electrodeposition on transparent conducting substrates (FTO) and investigates their photoelectrochemical (PEC) behavior and unassisted photocatalytic (PC) activities for solar chemical conversion in aqueous solutions. We observe that the surface property, crystalline structure, PEC, and PC performance for Solar chemical conversion are significantly influenced by the synthetic conditions. Optimized Cu-based delafossite catalysts exhibit suitable energetics for solar chemical conversion. However, we have identified a challenge with rapid electron-hole recombination in this copper-based delafossite material due to its narrow bandgap, posing a disadvantage in solar chemical conversion. To address this issue, we introduce a hole extraction underlayer deposited on FTO substrate for the catalyst. The primary roles of the underlayer are to establish a robust contact between the delafossite catalyst and substrates, facilitate hole transfer, and improve the deposition kinetics of the delafossite precursors. Additionally, the underlayer plays a secondary role in establishing firm contact between the substrate and catalyst. Through this underlayer, we were able to improve the Faradaic efficiency (F.E.), Solar-to-chemical conversion (STC) efficiency and selectivity of solar chemical conversion. Furthermore, we provide clear insights into the interests through Density Functional Theory (DFT) calculations. This research was supported by the National Research Foundation of Korea (RS-2023-00246948), Korea Polar Research Institute (PE24124) and Korea Water Cluster (KWC) as Korea Water Cluster ProjectLab.
Technological Advances for Temperature-Dependent Operando Electrochemical Liquid Cell Scanning Transmission Electron Microscopy Studies of Energy Materials
Authors: Stephens Katherine Marusak , Yang Yao , Walden Franklin Stampley , Marthe Nelson Luis , Wellborn Patrick Smith , McConnell Jennifer , Damiano John
Published: December 2024

The study of in situ or operando electrochemistry entails observing electrochemical behavior of samples in environments as close to “real working conditions” as possible. Scanning/transmission electron microscopy (S/TEM) enables researchers to characterize physical behavior on the sub-nanometer scale, but conventional S/TEM techniques require sample imaging and analysis in a high-vacuum environment. Recent advances in sample holder technology for S/TEM – specifically, the introduction of closed-cell S/TEM holders and the development of MEMS-based sample supports – have overcome this limitation. Closed-cell holders allow researchers to study their electrochemical systems in liquid, including the option to flow or exchange electrolyte across the sample, by hermetically sealing the experiment from the high-vacuum environment of the S/TEM column. MEMS-based sample supports with integrated electrodes, thin membrane windows, and controlled flow of electrolyte allow researchers to apply electrical stimuli while imaging. Together, these technologies allow the direct observation of processes at the nanoscale that influence material performance, such as the formation of the solid electrolyte interphase (SEI) layer during lithium-ion battery cycling [1], the preferential corrosion of stainless steel at sulfite [2] and silicate [3] inclusions, and the dynamic evolution of shape-controlled nanocrystals for CO2 reduction [4-6]. Understanding the structure-function relationship of these materials at the nanoscale facilitates the efficient innovation of new materials that are more functional, cost-efficient, and environmentally friendly.

In this presentation, we will share initial results from the next generation of in situ electrochemistry systems, pushing closer to “real working conditions” through advanced temperature control of the electrode-electrolyte interface. Many applications require increased temperatures, including research on fuel cell catalysts and corrosion. We will discuss the kinetics of well-known redox couples (Figure 1a) and of dendrite formation (Figure 1b) as a function of the temperature at the anode surface, the different spectroscopic techniques available when in situ electrochemistry is coupled with electron microscopy, and the implications of this new technology to research across numerous application fields including fuel cells, ionic liquids, batteries, corrosion, and electrocatalysis.

[1] W. Dachraoui, et al.
ACS Nano
2023
17(20), 20434-20444

[2] D. Kovalov, et al. Corros. Sci.
2022 199, 110184

[3] M. Tian, et al. Corros. Sci.
2022 208, 110659

[4] Y. Yang, et al.
Nature
2023 614, 262-270

[5] Y. Yang, et al.
J. Am. Chem. Soc.
2022
144(34), 15698-15708

[6] A.M. Abdellah, et al.
Nat. Commun.
2024 15, 938

Figure 1
(Invited) Manipulating Water Using Aprotic Solvents for CO2 Electrochemical Reduction
Authors: Amanchukwu Chibueze
Published: December 2024

Carbon dioxide (CO2) electrochemical conversion is vital because it provides a pathway to efficiently valorize CO2 and incentivize CO2 capture. Electrocatalytic CO2 reduction reaction (CO2RR) is of great interest because it is scalable and can be done at ambient temperature and pressure. However, these reactions are typically performed in water which suffers from undesired hydrogen evolution reaction (HER) from water breakdown. Aprotic nonaqueous electrolytes can suppress HER and enable a wider range of catalysts for CO2RR. However, water is still needed as a proton source and to stabilize charged intermediates. Here, we study the influence of aprotic electrolyte solvent on modulating the water microenvironment, solvation, and dynamics for CO2RR. Furthermore, we probe changes to the water chemical environment in different aprotic media and the ability of aprotic electrolytes to enhance CO2RR or suppress HER. Our work pushes the field in the understanding of electrolyte solvent and water effects for electrochemical transformations such as CO2RR and HER.
(Invited) Co-Doping of Tungsten Suboxide for Enhancing the Performance of Flexible Supercapacitors
Authors: Shim Jae-Jin , Thalji Mohammad R , Chong Kwok Feng
Published: December 2024

A crucial hurdle in developing supercapacitors is the creation of metal oxides with nanoscale structures that possess improved chemically active surfaces, ion/charge transport kinetics, and minimized ion-diffusion pathways. A metal-doping strategy to produce oxygen vacancies and increase electrical conductivity has proven effective for designing high-performance materials for energy storage devices. Herein, cobalt-doped tungsten suboxide (Co-doped W18O49) is grown on carbon cloth (CC) using a solvothermal approach and used as an electrode material for supercapacitor applications for the first time. Through this strategy, structurally distorted W18O49 is obtained by detecting a more apparent amorphous area caused by forming more oxygen vacancies with the bending of the lattice fringes. Benefiting from the synergy of more oxygen vacancies, increased lattice spacing, a high specific surface area, and accelerated ion diffusion, the Co-doped W18O49/CC electrode achieves a specific capacity of 475 C g−
1 (792 F g−
1) at a current density of 1.0 A g−
1, which is superior to that of the undoped W18O49/CC (259 C g−
1, 432 F g−
1) and among the highest reported to date. Interestingly, the asymmetric supercapacitor device assembled using Co-doped W18O49/CC//AC/CC can provide a high energy density of 35.0 Wh kg−
1. This strategy proves that the distortion of the W18O49 structure by Co doping improves the ion storage performance and self-discharge behavior. Also, it can enhance the energy storage performance of other electrode materials.

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Figure 1
(General Student Poster Award Winner, 3rd Place) Toward High Performance All-solid-state Lithium Batteries with Low Volume Change V-based High-capacity Positive Electrode Materials
Authors: Ono Teppei , Konuma Itsuki , Ugata Yosuke , Yabuuchi Naoaki
Published: December 2024

Toward a sustainable society through the maximum use of electric vehicles and renewable energy, the development of high energy lithium-ion batteries is urgently required. Recently, Li8/7Ti2/7V4/7O2 (LTVO), a member of the binary system of x Li2TiO3−(1−x)LiVO2, has been reported to offer a high reversible capacity of 300 mA h g–1 with a near dimensionally invariable character during charge and discharge and has been applied for the positive electrode material of all-solid-state batteries.1 However, the synthesis of LTVO requires high-temperature calcination (at 900 °C) and high-energy ball milling (at 600 rpm for 36 h) for nanosizing, and the synthesized sample is a Li deficiency phase associated with partial oxidation of V ions. In this study, the optimized synthesis process for LTVO is explored to improve the efficiency of material synthesis and suppress the loss of initial Li content in LTVO. LTVO was synthesized by calcination at various temperatures for 12 h, and a single-phase sample was obtained at ≥700 °C. In addition, efficient synthesis is achieved by shorting the heating duration to 3 h. To reduce the particle size, the sample calcined at 700 °C for 3 h was mechanically milled with different rotation speeds for 6 h. Compared with the as-prepared sample, the mechanical milled samples deliver a larger reversible capacity because the ball-milling treatment significantly reduces the particle size and shorten the migration length of Li ions in active materials. The sample milled at 450 rpm delivers a larger capacity than the sample milled at 280 rpm, but further increase in the rotation speed from 450 to 600 rpm does not affect the reversible capacity. In addition, the initial Coulombic efficiency is lower than 100% for each sample, suggesting the suppression of the formation of Li deficient phases through mechanical milling.From these results, the mechanical milling at 450 rpm for 6 h is considered to be the best condition to synthesize nanosized LTVO. The impact of synthesis conditions on electrochemical properties of LTVO and the application of optimized LTVO to all-solid-state batteries will be discussed in detail.

Acknowledgment
: This work has been partly supported by the projects (SOLiD-Next, JPNP23005)”, commissioned by the New Energy and Industrial Technology Development Organization (NEDO).

References:

1. Konuma et al., and N. Yabuuchi, Nat. Mater., 22, 225 (2023).
Promoting the Radical-Mediated Pathway and Li₂S Conversion By N-Doped Carbon-Embedded Cobalt-Doped Titanium Nitride Electrocatalyst with High Donor-Number Solvent for Lean Electrolyte Lithium-Sulfur Batteries
Authors: Park Gwan Hyeon , KIM Minho , Kang Song Kyu , Ji Junhyuk , Kim Won Bae
Published: December 2024

Lithium-sulfur (Li-S) batteries are recognized as some of the most promising candidates for next-generation batteries, owing to their high specific capacity, cost-effectiveness, and lightweight properties. Despite these advantages, the dissolution of the sulfur leads to the shuttling effect of long-chain lithium polysulfides (Li2Sx, 4≤x≤8). Moreover, the lean electrolyte system experiences a reduction in ionic transport due to the formation of ion-pairing and clusters of polysulfides. Therefore, the development of electrolytes that can stabilize the solvation structure of lithium-polysulfide and the introduction of electrocatalysts to suppress the shuttling effect are required for lean electrolyte lithium-sulfur batteries.

High donor-number solvents can stabilize the Li+-solvated structure by effectively shielding the Li+ ion’s effective nuclear charge. This Li+-solvated structure, in coordination with high donor-number solvents, can effectively interact with tri-sulfur radicals and long-chain polysulfides, which possess relatively delocalized negative charges. As a result, a high donicity electrolyte can enhance sulfur utilization by increasing the solubility of polysulfides. However, the poor compatibility of high donor-number solvents with Li metal presents a challenge, making their excessive use impractical. Therefore, optimizing the amount of high donor-number solvent is essential. Through careful optimization, it is possible to achieve high donicity electrolyte conditions that are compatible with Li metal. The 1 vol% N,N-Dimethylacetamide (DMA) in 1,2-dimethoxyethane (DME)/1,3-dioxolane (DOL) co-solvent (DMA:DME:DOL=1:49.5:49.5 vol%) electrolyte achieved a higher discharge capacity after 20 cycles compared to both a low donicity (DME/DOL, 1:1 vol%) and a high donicity (DMA/DOL, 1:1 vol%) electrolyte.

Electrolyte modification alone cannot completely suppress the shuttling effect, as the radical-mediated pathway activated by high donor-number solvent leads to the presence of tri-sulfur radicals. Recent research has investigated the ferromagnetic catalysts to enhance the adsorption of polysulfides through the Lorentz force and facilitate the conversion of Li2S with spin polarization in lithium-sulfur batteries. Introducing ferromagnetism through cobalt-doping into N-doped carbon embedded titanium nitride nanowires electrocatalysts could improve the adsorption of polysulfides and tri-sulfur radicals, as well as their conversion to Li2S and promote radical-mediated pathways with high donor-number solvents in lean electrolyte lithium-sulfur batteries. Consequently, N-doped carbon-embedded cobalt-doped titanium nitride nanowires on separator within the 1 vol% DMA electrolyte achieves a high discharge capacity of 454.8 mA h g−1 after 120 cycles with sulfur loading of 3.6 mg cm−2 and E/S ratio of 10 μL mg−1.
Analysis of the Initiation of Pitting Corrosion in Al Alloys Using Model Specimens Prepared by Spark Plasma Sintering
Authors: Katsuyama Tomoki , Nishimoto Masashi , Muto Izumi
Published: December 2024

In Al alloys, intermetallic particles (IMPs) play an important role in the initiation of pitting corrosion though the process of growing pit is unclear. IMPs in commercial Al alloys are fine and it is difficult to elucidate the mechanism of pitting corrosion by using the alloys. Therefore, in this study, model specimens were fabricated in which coarse IMPs were dispersed, and analysis of pitting corrosion was conducted by using these specimens.

Pure Al powders were mixed with Pure Fe or Cu powders and then they were sintered. After sintering, they were hot forged, and heat treated. To analyze the corrosion behavior, open circuit potential was measured in 0.1 M NaCl solution adjusted to pH 6.0.

These specimens contained dispersed phases of different colors from the Al matrix phase. In the Cu powders added specimens, the phases were Al2Cu and in the Fe powders added specimens, the phases were Al3Fe. After open circuit potential measurement, in specimens containing Al2Cu, the IMPs turned from grey to black and trench formed around the IMPs. In specimens containing Al3Fe, crystallographic pits occurred.
Perpendicularly Stacked Array of PTFE Nanofibers As a Reinforcement for Highly Durable Composite Membrane in Proton Exchange Membrane Fuel Cells
Authors: Lee Kyung Ah , Lee Ji Hyun , Hwang Chang-Kyu , Yoon Ki Ro , Sung Yung-Eun
Published: December 2024

The configuration of reinforced composite membrane (RCM), composed of porous polytetrafluoroethylene (PTFE) as a mechanical reinforcement and perfluorosulfonic acid (PFSA) as a proton conductive polymer has gained a large interest due to its promisingly high performance for polymer electrolyte membrane (PEM) fuel cells. However, the inaccessible polymeric nanocomposites in preparing RCMs are still faced with critical challenges associated with immiscible interactions between hydrophilic sulfonate groups in PFSA and the hydrophobic nanoporous PTFE matrix. Herein, we report a well-refined and facile fabrication strategy for producing a cross-aligned PTFE (CA-PTFE) framework. The electric-field guided electrospinning enables the creation of unique micron-scale, grid-type PTFE matrix, which is synthesized by annealing of electrospun conjugated polymers resulting in the removal of carrier polymer and the formation of continuous fibrious structure via fusion of PTFE particles. The CA-PTFE RCM embodying uniformly impregnated PFSA in a grid-type PTFE matrix, facilitates hydration of the membranes, with minimal swelling and efficient diffusion of protons through concentrated sulfonate groups. The CA-PTFE RCM adopted cell showed outstanding fuel cell currents during both low and high humidity operation, with a current density of 1.38 A cm−2 at 0.6 V and maximum power density of 0.85 W cm−2 under RH 100% condition. Furthermore, the CA-PTFE RCM was able to achieve a long-lasting single-cell operation with a significantly low hydrogen crossover (less than 5 mA cm−2 at 0.4 V) even after 21,000 wet/dry cycles, which surpasses the standard of membrane durability for transportation application. The rational design of fibrous PTFE reinforcements opens up new engineering opportunities for the future development of high-stability PEM fuel cells.