bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of Dry-Made NMC 811 Electrodes with Varying Binder and the Conductive Agent Contents
Authors: Uzun Kubra , Alolaywi Haidar , Thapa Santosh , Cheng Yang-Tse 
Published: August 2024

Lithium-ion battery electrode materials consist of active materials (AM), conductive agents, and binders. Although conductive agents and polymeric binders occupy a small portion of the electrode, they play an indispensable role. Conductive agents are needed to improve the electronic conductivity of the electrode, while binders ensure mechanical integrity by providing particle/particle cohesion and electrode-film/substrate adhesion. Optimizing the interactions of active materials, conductive agents, and binders is crucial for achieving the desired electrode performance and durability. Although multiple studies have explored the impact of electrode composition for slurry-based electrodes, it is still unclear how composition affects the electrodes made by dry processes. In this study, we performed a detailed investigation of the effects of the different electrode compositions by changing the ratio of polyvinylidene difluoride (PVDF) binder and carbon black (CB) for dry-made LiNi0.8Mn0.1Co0.1O2 (NMC 811) electrodes. The electrostatic spray deposition method was used as a dry electrode fabrication process due to its many advantages, such as reduced energy consumption and inexpensive processing requirements. We investigated electrodes of four different compositions, 96:3:1, 96:2:2, 90:7.5:2.5, and 90:5:5 (AM:PVDF: CB), corresponding to PVDF/CB mass ratios of 1:1 and 3:1.
We found that electrodes with a high PVDF/CB ratio of 3:1 have larger impedance than electrodes with a low PVDF/CB ratio of 1:1 due to the insulating aggregates of PVDF alone, causing deteriorated electrochemical performance. At the PVDF/CB ratio of 1:1, an even distribution of PVDF/CB on the AM particle surfaces and in the pores between the AM particles was observed. For both PVDF/CB ratios of 1:1 and 3:1, increasing the total amount of PVDF and CB (e.g., decreasing the AM amount) in the composite electrode enhanced both the C-rate and cycling performance. However, electrodes with the PVDF/CB ratio of 1:1 at high AM content (96%) still showed a comparable C-rate performance to that with lower AM content (90%). Thus, dry-made electrodes with high AM content can achieve a good high C-rate performance, especially for high-energy-density applications.
This study provides a better understanding of the effects of CB/PVDF, which is key to finding an optimal structure and composition of the dry-made electrodes.
(Invited) Carbon Sulfonation Using Plasma: Trial to Enlarge Treatment Capacity
Authors: Takeuchi Nozomi , Deng Siqi , Yao Kaixun , Takahashi Katsuyuki , Tachibana Kosuke , Hieda Junko , Li Oi Lun 
Published: August 2024

Heterogeneous catalysis is a promising technology in conversion of biomass to biofuels because of its high reactivity, easy post-separation, and great recyclability compared to homogeneous catalysis. Various functionalized catalytic materials have emerged as promising alternatives to the homogeneous liquid acid catalyst, such as carbon materials, metal–organic frameworks, and metal nanoparticles. Among them, carbon materials such as carbon nanotube, graphene oxide, carbon black, and so on have been investigated as catalysts for cellulose hydrolysis to produce glucose.
Carbon materials show considerable catalytic activity by functionalization with active acidic groups including hydroxyl groups (-OH), carboxyl groups (-COOH), and sulfonic groups (-SO3H). Hydroxyl and carboxyl groups on the carbon catalysts act as connection center to access cellulose, where sulfonic group serves as the active site to cut off the linkage between glucose units in cellulose. So, the surface modification of carbon materials with these functional groups, namely, carbon sulfonation process, becomes the determining step to producing efficient carbon acid catalysts. Conventional methods for the carbon sulfonation are the hydrothermal and reflux method, in which hazardous chemicals are necessary, such as concentrated sulfuric acid (95–98%), chlorosulfonic acid, fuming sulfuric acid, or 4-benzenediazoniumsulfonate under elevated temperature for dozens of hours.
As a green and effective carbon sulfonation process, we have utilized plasma generated in contact with dilute sulfuric acid. Recently, we have investigated the mechanism of carbon sulfonation in GLIP processes. Active species produced near the gas–liquid interface such as •OH, SO3, and HOSO2• probably play important roles in carbon sulfonation. We are currently trying to enlarge the treatment capacity of carbon sulfonation by two methods, namely parallel plasma generation with ballast capacitors and large-area plasma generation by a dielectric barrier discharge. Also, effects of gases used for plasma generation such as air and Ar on the carbon sulfonation are investigated.
This work was partially supported by the Environment Research and Technology Development Fund (JPMEERF20223R01) of the Environmental Restoration and Conservation Agency of Japan.
(Invited) Numerical Simulation of an Atmospheric Pressure Streamer Discharge and Induced Chemical Reactions
Authors: Komuro Atsushi 
Published: August 2024

Streamer discharges are a type of non-thermal plasma produced by high-voltage electrical discharges, and have great potential as highly reactive chemical reaction fields. This is mainly due to the generation of high energy electrons that produce chemically active species. The applications of non-thermal plasma have attracted considerable interest in a wide range of industries. However, each radical has a different role in the plasma application and their reaction mechanism is also different. It's therefore important to understand exactly when, where and how much of these reactive species are produced in order to improve the treatment efficiency of atmospheric pressure plasma applications. Against this background, the aim of this study is to develop a simulation model capable of accurately predicting the chemical reactions of radicals. With a sufficiently validated simulation model, it would be possible to use such a model to design chemical reaction fields.
The model consists of the first-order electrohydrodynamic model for electrons and positive and negative ions within the drift-diffusion approximation. Axis-symmetric coordinates were used to simulate the streamer discharge in air at atmospheric pressure. The electron transport and source parameters were calculated using two-term bltzmann equation and published electron impact cross-sections. The chemical reaction model used in this study includes electron impact collisions (excitation, ionisation, dissociation, recombination, attachment and detachment), ion recombination and the reactions of neutrals. In order to demonstrate the validity of the simulation, the light emission of the discharge is first compared between experiment and simulation. Then the spatial and temporal variations of each radical are simulated and compared with the simulation. In this talk, I will present the process of validation and verification (V&V) of the streamer discharge simulation and then the mechanism of radical production revealed by the simulation.
Enabling Fast Charging of High Loading Batteries Via Operando Microscopy Diagnosis of Lithium Plating Limits
Authors: Gopal Rajeev , Sittisomwong Poom , Bai Peng 
Published: August 2024

While lithium-ion batteries have undergone substantial development, enabling their widespread adoption in consumer electronics, a critical need persists—achieving faster charging even at lower temperatures. This realization is hindered by lithium plating, which reduces capacity and cycle life.
A possible strategy involves engineering the electrolyte to improve the ionic transport across/into the graphitic anode. Based on recent studies and simulation results, the traditional carbonate-based electrolyte was replaced with a more promising ether-based electrolyte and tested in our specially designed operando capillary full cells. Here the axial lithiation of graphite could be monitored in real-time and lithium plating precisely correlated to the voltage response. Lithium-ion transport at the face of the electrode was further evaluated with our in-plane imaging setup. The demonstrated performance improvements were then investigated in larger high loading cells at different temperatures and cycling conditions.
Our results reveal significantly better charging characteristics for the ether-based electrolyte, not only showing better particle activation but also increasing the capacity (as much as 40%) before the onset of lithium plating. This prompts a compelling inquiry into the roles played by ether driven solid electrolyte interface (SEI) formation and possible co-intercalation processes. How might these mechanisms contribute to the observed enhancements, and what implications could they have for the broader landscape for fast charging batteries.

Figure 1
Molecular Understanding of Li Metal Anode
Authors: Yu Weilai , Cui Yi , Bao Zhenan 
Published: August 2024

Developing new liquid electrolyte is a promising approach to enable the next-generation high-energy Li metal battery for wide-ranging application such as electric vehicles (EV). However, the high reactivity of Li metal interface renders it crucial to form favorable solid-electrolyte interphase (SEI), via active electrolyte decomposition, for highly reversible operation of Li-metal anode (LMA). Therefore, deeply understanding how the molecular structures of electrolyte species precisely control both the interfacial reactivity and the operational reversibility of LMA, can further guide and inspire new electrolyte systems with progressively improved battery performance.
Herein, we systematically investigated the impact of Li salts with different imide anions dissolved in ether-based solvent, on the resulting Coulombic efficiencies (CE) of LMA, whereas beneficial and detrimental molecular motifs were first identified. By leveraging the non-washing XPS protocol newly developed at Stanford, we managed to uncover the distinct molecular reactivity leading to reductive bond cleavage as well as new bond formation at Li-metal potential. Such nanoscale reactivity of SEI-forming reactions was discovered to profoundly govern the macroscopic performance of LMA, which simultaneously emphasized the significance of electric double layer (EDL). Importantly, aided by gas-titration experiments to quantify the by-products in SEI, we revealed the critical molecular origins of irreversible capacity loss of LMA during continuous Li-metal plating and stripping. These new insights allow us to formulate rational strategies of molecular engineering to design LMA interface with high reversibility and minimal side reactivity.
The Effect of Shape in Porous Electrodes on Cell Resistance and Chemo-Mechanical Stresses
Authors: Lin Tiras Y , Roy Thomas , Worsley Marcus Andre , Bucci Giovanna 
Published: August 2024

In contrast to conventional planar electrodes, the use of electrodes with a three-dimensional (3D) shape has been shown to be an effective way to increase both the power and energy densities of a Li-ion battery. These 3D shapes allow batteries to overcome some of the capacity and rate performance trade-offs. For instance, they enable higher active-material loading, while keeping the transport pathways fixed and allowing for better material utilization. There are a variety of ways electrodes can be shaped: each electrode can be individually shaped and separated by a planar separator, or they can be completely intertwined with one another. In this talk, we consider both cases: a half cell with an electrode shape described by a sine wave and a full cell following an interdigitated design, where alternating planar fins protruding from the cathode and anode sandwich the electrolyte. First, we seek to understand how the electrode shape affects the electrical resistance of the cell based on a simple electrostatics model with a linearized Tafel expression. We identify the regimes of electronic to ionic conductivity ratios, Wagner numbers, and porosities that benefit most from electrode shaping, with a particular focus on low temperature electrolytes with reduced conductivity. Next, battery cycling is known to cause volumetric expansion and contraction of the electrodes. Therefore, we explore the chemo-mechanical stresses that arise in the same shaped electrodes with a solid electrolyte. To do so, we solve for the mechanical equilibrium for stress and deformation in the presence of an applied isotropic strain. By examining the stress concentrations at the electrode/electrolyte interface, we elucidate the likely failure mechanisms – interface delamination, crack propagation – of shaped electrodes in comparison to planar electrodes. Overall, we aim to provide design guidelines for how electrode shapes can be chosen to provide both low cell resistance and acceptable mechanical resilience.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL release number: LLNL-ABS-857536.
Understanding Organic Components of Solid Electrolyte Interphase on the Lithium Metal Anode
Authors: Lopez Jeffrey 
Published: August 2024

Lithium ion batteries have become the dominant form of energy storage used in consumer electronics and, recently, electric vehicles. However, high costs have prevented widespread deployment of lithium ion batteries for applications other than portable electronics, and the safety issues associated with liquid organic electrolytes remain to be addressed. In order to enable the greater utilization of electric vehicles, allow for grid scale energy storage, and meet the demands of new electronic applications, new materials for high energy density batteries must be developed. High capacity electrode materials like lithium metal have the potential to facilitate these technologies, but lithium metal electrodes are presently limited by significant side reactions, poor quality deposition, and the potential to form hazardous dendrites. Therefore, it is important to develop a clear understanding of the surface reactivity and growth behavior of the lithium metal at the interface with the electrolyte in order to enable stable long-term cycling.
The products that form as a result of electrolyte decomposition reactions at the electrode interface are known to be extremely important in determining the final cell performance, yet characterizing the organic components of the solid electrolyte interphase (SEI) proves to be challenging with typical techniques. In this presentation we will discuss a combination of in operando and ex situ techniques developed in efforts to more comprehensively characterize the reaction intermediates and organic SEI products of electrolyte reduction reactions. Specifically, we employ electron paramagnetic resonance (EPR) spectroscopy to identify radical intermediates and clarify electrolyte reduction mechanisms. Furthermore, SEI product formation with respect to electrochemical potential and time will be described using data obtained from in operando ATR-FTIR. ATR-FTIR is a powerful method for characterizing organic species, but typical materials such as Ge, Si, and ZnSe react with lithium metal during deposition. In this talk, the development of a diamond based operando cell and its application to the characterization of organosulfur and fluorinated electrolytes will be discussed. With the understanding developed from these two techniques we provide new insights into the formation and chemical nature of SEI components that promote stable cycling of lithium metal electrodes.
Cracks in Polycrystalline Li(NiMnCo)O2 Particles Enable Rapid Discharging of Li-Ion Batteries
Authors: Min Jinhong , Li Yiyang 
Published: August 2024

The degradation of capacity in Li-ion batteries during charging and discharging cycles has been a persistent challenge in advancing battery lifetime. Among the commonly accepted causes of capacity degradation is the formation of cracking along the grain boundaries of polycrystalline NMC particles. These cracks are known to occur from the anisotropic expansion and contraction of the crystal lattice induced by the (de)intercalation of lithium.
To address this issue, single crystalline NMC particles were introduced, lacking grain boundaries and seemingly less prone to developing cracks. batteries utilizing single crystalline particles exhibited improved capacity retention. However, in terms of rapid charging and discharging, these single particle batteries experienced a sudden increase in overpotential compared to polycrystalline particle batteries. Yet, a clear explanation for this abrupt rise in overpotential during rapid charging and discharging in single crystalline particle batteries has remained elusive.
In this study, we investigated the rate-capability of individual single and polycrystalline NMC particles using an innovative high-throughput single-particle electrochemistry platform. Based on our rate-capability findings, we argue that the cracks, previously identified as a factor contributing to capacity degradation, are actually a crucial element enabling rapid charging and discharging in polycrystalline particles.
Electrochemical Quartz Crystal Microbalance Study on the Electrodeposition of Fe, Co and Fe-Co Alloys
Authors: Ispas Adriana , Bund Andreas 
Published: August 2024

Cobalt-iron alloys are interesting soft magnetic materials which are used for example in magnetic sensors and transducers. They can be obtained by different techniques such as PVD, magnetron sputtering, or casting. One easy and not very expensive way to produce these alloys is the electrochemical deposition technique, which was also chosen in this study.
This contribution will describe the electrodeposition of Co, Fe and Fe-Co alloys (Fe70Co30) from an aqueous sulphate-based electrolyte containing boric acid as a buffer and sodium citrate and citric acid besides the metal sulphates. Potentiostatic step experiments and cyclic voltammetry were performed in parallel to electrochemical quartz crystal microbalance. Thus, we could identify the potential at which the deposition of the metals sets in, the mass of the deposited species as well as the current efficiency. We could also extract the partial current due to hydrogen evolution reaction and the partial current due to individual metal or their alloys from the total current density. The morphology and structure of the deposited films were investigated by means of SEM and XRD, respectively. The grain size of the deposits was calculated from the XRD data using Scherrer equation. Addition of citric acid to the electrolyte results in the smaller grain size of the deposited Fe-Co films.
Preparation of Oriented Nanoporous Magnetite Films by a Template-Free Solution Process from Iron Oxyhydroxide Films
Authors: Shinagawa Tsutomu , Kanemoto Yuya , Ohtaka Atsushi 
Published: August 2024

Nanoporous oxide films composed of nanocrystal assemblies with an aligned crystallographic orientation are key nanostructures for efficient interfacial reactions. However, a simple, template-free method for their formation remains a challenge. Layered metal hydroxide (LMH) films are a promising precursor for spontaneous formation of nanoporous oxide films.[1-4] LMHs have a layered structure comprising 2D sheets of edge-shared octahedral hydroxide, i.e., brucite structure, with or without interlayer anions and water molecules. Calcination of LMH results in dehydration, anion elimination, and volume shrinkage, leading to the spontaneous formation of nanoporous oxides.
In this study, we have prepared nanoporous and ferrimagnetic magnetite (Fe3O4) films by using layered iron hydroxides, namely, green rust (GR), as a precursor. Generally, GR has a brucite-type structure containing Fe2+ and Fe3+ ions, and is highly susceptible to oxidation by oxygen in water and air, leading to the formation of iron oxyhydroxides (FeOOH). Here, GR films were electrochemically deposited on FTO substrates in an aqueous solution containing Fe2+ and NO3
− ions at room temperature. Drying the GR films in air resulted in the formation of two-type FeOOH films, depending on the electrodeposition condition. Characterization using X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and FT-IR spectroscopy revealed that one is [010]-oriented γ-FeOOH films, and the other is [001]-oriented δ-FeOOH films. The obtained FeOOH films had a mille-feuille like morphology with 500–700 nm thickness. Heat treatment of these two-type FeOOH films under vacuum at 500 °C resulted in the formation of [110]- and [111]-oriented nanoporous Fe3O4 films. The obtained Fe3O4 films showed a ferrimagnetic behavior in VSM measurements and had a nanoporous structure comprising nanoparticles with 50–100 nm diameter.
Finally, a possilble interpretation for the observed orientation relationships between the FeOOH and Fe3O4 was also discussed on the basis of pyrolysis intermediates of FeOOH and similarity in their atomic arrangements.

References

T. Shinagawa, M. Watanabe, T. Mori, J.-i. Tani, M. Chigane and M. Izaki, Inorg. Chem., 57, 13137 (2018).

T. Shinagawa, M. Chigane and M. Izaki, ACS Omega, 6, 2312 (2021).

T. Shinagawa, M. Chigane and M. Takahashi, Cryst. Growth Des., 22, 4122 (2022).

T. Shinagawa, N. Kotobuki and A. Ohtaka, Nanoscale Adv., 5, 96 (2023).

Figure 1
Molecular Dynamics Study of Adhesion-Related Structural Properties for PVDF-HFP Polymer Binders
Authors: Jeong Seung Weon , Lee Sangheon , Lim Hyung-kyu 
Published: August 2024

The current lithium-ion battery (LIB) market is expanding rapidly. Binders are essential to maintaining the high capacity and longevity of batteries. These binders can be classified into organic binders used for cathodes and aqueous binders used for anodes. Among them, Poly(vinylidene fluoride) (PVDF) binder is a representative organic binder that offers excellent electrochemical stability. To solve low adhesive force and weak mechanical strength of conventional PVDF binders, hexafluoropropylene (HFP) is added to improve these properties. However, the present poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) binders still show lower adhesive force than other polymeric binders, and therefore further research works are necessary.
In this study, we employ classical molecular dynamics (MD) simulations to investigate the structural properties of the PVDF-HFP copolymers. To create realistic disordered PVDF-HFP polymers, we develop a computational scheme that can randomly arrange the angles and sequences of the constituent polymer chains. By varying the ratio of randomly arranged PVDF-HFP copolymers to 0/100, 5/95, 10/90, 15/85, and 20/80, we build a solution model that mimics the HFP concentration of PVDF-HFP (0–20%, Sigma Aldrich) used in the actual experiments. N-methyl-2-pyrrolidone (NMP) used as solvents. To create a large-scale model, we utilize the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) and set parameters by using OPLS force field. This allows us to build a simulation model containing approximately 40,000 atoms consisting of 10 PVDF-HFP polymers and 1500 NMP monomers.
After creating the simulation model, approximately eight steps of molecular dynamics simulation are performed by referring to the process of making the actual polymer film. In this process, NMP molecules are evaporated to produce a polymer film consisting only of PVDF-HFP polymers. Then we perform the adhesion analysis by applying forces to five polymer film models with different composition ratios in various conditions. Throughout these processes, we find the characteristic changes depending on the composition ratio. Finally, we will present the possible routes that can lead to the enhanced adhesive properties of PVDF-HFP, which is a key requirement to the development of high performance binders.