bluuebunny/crossref_metadata_2025 huggingface dataset:
Unravelling Energy Conversion Mechanisms in Photocatalysts and Biohybrids By Operando Functional Imaging
Authors: Mao Xianwen
Published: December 2024

(Photo)electrochemical systems have continued to play critical roles in modern technologies that promise to tackle some of the world’s most pressing challenges associated with climate change, renewable energy and clean water. In this talk, I will describe my efforts in developing operando functional imaging tools to understand materials properties at the single-entity level (e.g., single particles, single cells and single interfaces). I will focus on (photo)electrochemical properties of emerging materials, such as photocatalysts and biohybrids, which are important for a range of energy and environmental applications. I will discuss in detail single-entity-level insights inaccessible from bulk-level, ensemble-averaged measurements. (References: Mao et al., Nature Mater. 2022, 21, 331; Nature Chem. 2023, 15, 1400-1407)
(Invited) In Situ X-Ray Spectroscopy for Clean Energy: Insights into Reactive Intermediates
Authors: Pushkar Yulia
Published: December 2024

Transition from fossil fuels requires increased use of solar energy and electrification of chemical industries. To store the excess green electricity from wind and solar generation, batteries and electrolyzers are needed. Green hydrogen can also be produced via artificial photosynthesis where water is split by energy input of sunlight. Hydrogen can be later used in fuel cells. All these applications require new, electrochemically active materials and catalysts. To boost applications in energy storage and conversion, materials with exotic redox states are often desirable. X-ray spectroscopy is an excellent tool for in situ analysis of such energy storage and conversion systems in situ under working conditions.

In presentation I will discuss characterization of exotic Mn1+ proposed to play a role in the function of sodium-based Prussian blue analogues (PBA) batteries, a highly sought-out technology for industrial energy storage. Here, we report the detailed electronic structure characterization of uncharged and charged sodium-based manganese hexacyanomanganate anodes via Mn K-edge X-ray absorption spectroscopy (XAS), Kβ nonresonant X-ray emission (XES), and resonant inelastic X-ray scattering (RIXS).

For electrochemical and photoelectrochemical water oxidation high oxidation states of IrV, RuV and FeV are needed to activate water and form O-O bond. These species were generated in situ under catalytic conditions and characterized by hard X-ray XAS. Active catalyst such as [Ru(H3-Tpy)(Qc)Cl] was assembled into MIL-142 metal organic framework to produce device prototype for artificial photosynthesis. It delivered high photocurrent in the photo-electrocatalytic water splitting at pH=1 and unassisted photocatalytic H2 evolution under visible light with Pt as the co-catalyst. The high activity of this new system enables hydrogen gas capture from an easy-to-manufacture, scaled-up prototype utilizing MOF deposited on FTO glass as a photoanode.
(Invited) Faradaic Electron Transfer in Inner Helmholtz Plane
Authors: Kim Moonjoo , Chung Taek Dong , Park Sangmee
Published: December 2024

Since the electrical double layer (EDL) is where heterogeneous electron transfer occurs, understanding the effects of the electrode-electrolyte interface structure on electrocatalysis is important. The strong electric field in the EDL offers unique environment for electrochemical reactions by altering the solvation structure and mass transport of redox species. Yet, it is challenging to evaluate the physicochemical properties of the matter within EDL, especially for the inner Helmholtz plane (IHP), where most electrochemical reactions occur. This is largely because of the lack of an appropriate model system for experiments. In this talk, the microscopic environment in the IHP of ionic liquids (ILs) is investigated through the reorganization energy reflecting the solvation structure. Exceptionally fast mass transport of Br2 in N-methyl-N-ethyl-pyrrolidinium polybromide allows to obtain bromine reduction voltammograms in which the current plateau is governed by electron-transfer kinetic and to evaluate the reorganization energy based on the Marcus-Hush-Chidsey model. This enables investigation of the microscopic environment in the IHP of the IL affecting electrocatalytic reactions through reorganization energy. As a demonstration, titanium oxide-modified Pt was employed to show pH-dependent reorganization energy, which suggests the switch of major ions at the IHP as a function of surface charges of electrodes. On the other hand, regulating the potential of zero charge (PZC) of electrodes by surface modification and preparation of alloys with various elemental compositions, the surface charge sensitive-ionic structure in ILs is introduced.

References

Kim, M.; Park, S.; Chung, T. D., Heterogeneous electron transfer reorganization energy at the inner Helmholtz plane in a polybromide redox-active ionic liquid. Chem. Sci.
2022, 13(30), 8821-8828.

Kim, M.; Tetteh, E. B.; Savan, A.; Xiao, B.; Ludwig, A.; Schuhmann, W.; Chung, T. D., Reorganization energy in a polybromide ionic liquid measured by scanning electrochemical cell microscopy. J. Chem. Phys.
2023, 158(13), 134707.

Kim, M.; Tetteh, E. B.; Krysiak, O. A.; Savan, A.; Xiao, B.; Piotrowiak, T. H.; Andronescu, C.; Ludwig, A.; Chung, T. D.; Schuhmann, W., Acidic Hydrogen Evolution Electrocatalysis at High-Entropy Alloys Correlates with its Composition-Dependent Potential of Zero Charge. Angew. Chem. Int. Ed.
2023, 62(39), e2023100.
In Situ Probing Electrified Interfacial Molecular Anion Structures at Atomically Flat Gold Electrode
Authors: Mohseni Armaki Seyedamirhossein , Ahmadi Majid , Mol Arjan , Taheri Peyman
Published: December 2024

Electrochemical interfaces—buried between electrodes and electrolytes—are notoriously difficult to probe, and enormous efforts, both experimentally and computationally, have been devoted to this endeavour. Although some progress has been made, the microscopic structures of electrochemical interfaces remain elusive and a great challenge in physical sciences.[1]

Answering this question is not only of fundamental interest but also of technological importance in a broad range of research areas in science and technology, to name a few, energy storage in supercapacitors, electrocatalysis of relevance to energy and environmental applications, self-assembly of colloidal particles, ion transport across biological membranes, and mineralization processes in earth science. Despite its significance, molecular-level understanding of Electrified Double Layer (EDL) is largely missing, owing to its complexity and small scale making it difficult to probe. Because of the advent of advanced experimental (e.g., synchrotron-based techniques and Raman spectroscopy) and computational methods [e.g., ab intio molecular dynamics (AIMD)], it is not until recently that the microscopic structures of EDL have started to be unveiled. [2,3]

In this study, we employ in-situ Shell Isolated Nanoparticle Enhance Raman spectroscopy (SHINERS) to investigate the structures of electric double layers at electrochemical interfaces. Specifically, we focus on understanding the arrangement and surface interaction of anions on electrified gold single-crystal electrode surfaces under varying bias potentials. We discuss how these ions orient themselves and interact with the electrode surface, and how these interactions influence local permittivity and ion-surface attraction, ultimately impacting the structure and behavior of the EDL and electrochemical processes.

[1] Le et al., Sci. Adv. 2020; 6

[2] Li et al.,Nature Materials, 2020; 18

[3] Wang et al., ,Nature, 2021;600
High Local CO Concentration Generated By Delicate Control of Au Nanoparticles from Au-Cu2o Tandem Catalyst Boosts Electrochemical CO2 Conversion into Value-Added C2+ Products
Authors: Wang Suneon , Oh Jihun
Published: December 2024

The electrochemical reduction of carbon dioxide (CO2RR) holds promise for carbon capture and utilization (CCU), aiming to produce carbon-neutral fuels and valuable chemical intermediates. Copper (Cu) is recognized as the primary metallic catalyst facilitating C-C coupling reactions to yield multi-carbon compounds.

Many researchers have been developing Cu catalysts, such as oxide-derived Cu (OD-Cu), and tandem catalysts to increase the kinetics of C-C coupling. The investigation of tandem catalysts, especially those derived from oxides of copper (OD-Cu), has been conducted to improve selectivity towards multi-carbon compounds like ethylene and ethanol.

Nonetheless, the effect of the loading structure of the CO-producing catalyst within the tandem catalyst on CO2RR performance has not been fully explored. In this study, we synthesized Au nanoparticles with different sizes and loading densities on Cu2O through the galvanic replacement reaction and examined their influence on CO2RR properties.

Tandem catalysts containing smaller Au nanoparticles demonstrated heightened activity in the electrochemical CO2RR, leading to an anodic shift in potential. Additionally, tandem catalysts with smaller Au nanoparticles exhibited improved Faradaic efficiencies (FEs) and partial current densities (PCDs) for C2+ compounds. The tandem catalysts with larger Au nanoparticles also showed better CO2RR performance than the original OD-Cu; however, it was found that CO2RR results of the tandem catalysts with a small size of Au nanoparticles were superior to those with large size of Au nanoparticles.

Interestingly, the FEs and PCDs of n-propanol, a C3 product, increased as the coverage of Au nanoparticles increased. This behavior contrasts with the case of ethylene and ethanol. The maximum Faradaic efficiencies (FEs) of these C2 products from tandem catalysts did not exceed those from OD-Cu.

The effectiveness of the tandem effect relies on the localized concentration of CO, heightened by the CO-producing catalyst situated on the confined OD-Cu surface. The improvement of the selectivity towards the C3 product may come from the interface between the Au nanoparticles and OD-Cu, where the C1-C2 coupling reaction is favorable.

We utilized a Nickel single-atom catalyst (Ni-SAC) to create a high local concentration of CO within the catalyst layer. Despite this, we did not observe any tandem effect. This suggests that the proximity between CO active sites and C2+ active sites plays a crucial role in triggering the CO spillover effect. Our results shed light on a strategy for constructing efficient tandem structures in CO2RR.
(Keynote) Electrochemical Reduction of CO2 and Related Feedstocks to Long Carbon Chain Products
Authors: Yeo Boon Siang Jason
Published: December 2024

In this presentation, we share our recent works related to the development of catalysts for the electroreduction of CO2, CO, and other related small molecule feedstocks to oxygenates and long-chain hydrocarbons, which can be used as chemicals and fuels. We shall first show how C1-C6 alkanes and alkenes such as n-hexane could be formed. In particular, we reveal how their selectivities, such as branching ratios, could be controlled by tuning the applied electrochemical potentials and oxidation states of the catalysts. The catalysts that were found to work well were unexpectedly based on nickel and cobalt, rather than copper (which is generally known to reduce CO2 to C1-C3 molecules). We shall also show how we can use the flow rate of the CO(2) feed to tune its selective reduction towards products such as acetate and methanol. The mechanisms by which these aforementioned reactions occur are elucidated experimentally and by using DFT calculations.
Electrochemical Impedance Spectroscopy Sensors in the Sugar Bush to Detect Biofilms
Authors: Jackson Ruby , Palen Thomas , Ketteler Haley , Walk Seth , Randal Jesse , Warnat Stephan
Published: December 2024

The demand for maple syrup is increasing, and producers must improve efficiency to maintain high-quality products at a low cost. To meet transparency, density, color, and aroma standards, quality control systems are established throughout boiling processes. However, microbial growth in the harvesting infrastructure throughout the sugaring season has been a significant challenge, as biofilms reduce sap flow rates or cause clogging of sap lines. Microbial growth also degrades the product's quality by changing the syrup's color, taste, and viscosity. Therefore, smart farming is an essential solution that can bridge the gap between microbial growth monitoring and maple syrup quality. Wireless Sensor Networks in maple forests, also known as sugar bushes, are vital for monitoring processes such as sap harvesting using individual sensor nodes that send current biogeochemical information to a field station. A biofilm sensor is needed to indicate biofilm formation in real time.

This presentation introduces a microfabricated electrochemical impedance spectroscopy sensor (EIS) tailored to measure biofilm formation in sap infrastructure during the harvesting season, defined by temperature fluctuations between -10 and 20 ˚C. Impedance spectroscopy sensors were fabricated using standard evaporation, lithography, and wet chemical etching techniques. To increase the sensitivity of biofilm formation, interdigitated electrodes with a 15 µm gap between two electrodes were utilized, and 50 gold electrode pairs were implemented on a borosilicate glass wafer. Diced EIS dies were integrated into an additively manufactured housing that allowed electrochemical measurements in maple sap in the laboratory or sugar bush.

To test the efficacy of the EIS sensor, a Pseudomonas Sp. strain was extracted from maple sap harvested in 2023 at the Michigan State University Upper Peninsula Forestry Innovation Center and grown at room temperature. Sterile sap was filled into the flow cell and inoculated with microorganisms after 4 h. All experiments were performed in triplicates, and abiotic controls followed the same procedure minus the injection of cell culture enrichments.

Impedance data were captured every 30 minutes for 7 days, and impedance changes to the abiotic signal were characterized at defined frequencies. After 1 hour, an impedance change of 15% was observed. The impedance magnitude decreased over 7 days, indicating biofilm maturation. Biofilm growth on the EIS surface was confirmed with confocal microscopy. An impedance increase was observed in some cases, indicating biofilm detachment. Additionally, a model has been developed that relates the impedance response of maple sap to the required outdoor temperature range of -10 and 20 ˚C. Ultimately, this paper shows EIS as a valuable tool to characterize biofilm formation caused by maple sap.
(Invited) Multichannel Surface Plasmon Resonance Chip for Cell Evaluation By Medium Pattern Recognition
Authors: Kurita Ryoji , Sugai Hiroka , Tomita Shunsuke
Published: December 2024

We would like to present a pattern-recognition-based cell evaluation using a multichannel surface plasmon resonance (SPR) chip. The chip consists of five different cysteine derivatives immobilized on thin gold films and is capable of generating five different SPR sensorgrams for cell-secreted molecules in the culture medium. Two parameters were obtained from each SPR sensorgram and multivariate analysis was performed from a total of 10 parameters. Our system provided complex cell information rapidly (10 min) by simply introducing a small amount of cell culture medium (25 µL) to the chip, and the amount of information obtained was comparable to conventional biochemical assays combined.

Five cysteine derivatives (Cys, Ac-Cys, Cys-OEt, Boc-Cys and Pen) were used as cross-reactive probes. These cysteine derivatives were immobilized on five gold films in the SPR chip via gold-thiol binding. As these cysteine derivatives have different functional groups, the analyte interacts differently with each gold surface.

Tamoxifen (TAM), a therapeutic agent for the treatment of tumours, and human liver cancer cells (HepG2) were used as models to investigate changes in cellular activity when exposed to different TAM concentrations and durations. In addition, cell states were classified into four groups based on the results of biochemical assays to verify the correlation with conventional methods. They were classified according to albumin secretion, total protein content, apoptosis incidence, survival based on intracellular dehydrogenase and cell death based on extracellular dehydrogenase as shown in figure (a).

The culture medium was introduced into the SPR chip and the results of 20 samples were used as training data; the discriminant score plot by LDA showed a complex shift from Group A to D, with no overlap of the clusters corresponding to each group shown in figure(b). The main features of our sensor are: 1. rapid results with small amounts of culture medium; 2. no cell damage due to non-invasive analysis; and 3. analysis based on comprehensive information from the culture medium, independent of specific biomarkers.

Figure 1
(Digital Presentation) A Facile Molasse-Assisted Synthesis of LaFeO3 Lanthanum Iron Oxide Nanoparticles for Simultaneous Electrochemical Determination of Acetaminophen and 4-Aminophenazone
Authors: Paredes Cuaran Angela Maria , Castellanos Bernal Cindy Vanessa , Peñaranda Lopera Isabella , Prado Hernandez Victor Manuel , Morales Jimmy
Published: December 2024

Using a screen-printed carbon electrode modified with lanthanum iron oxide nanoparticles as a sensing device, the heterocyclic chemicals, acetaminophen and 4-aminophenazone, which are developing pollutants, were electrochemically destroyed in PBS buffer media at pH 5.5 in this study. X-ray diffraction was used to analyze lanthanum iron oxide nanoparticles LFO NPs, which were manufactured utilizing a low-cost and straightforward approach. The simultaneous determination of acetaminophen (AC) and 4-aminophenazone (4-AM) has been accomplished through the development and validation of a novel, sensitive electroanalytical approach. The electrochemical behavior of the emergent contaminants in this work was investigated using cyclic voltammetry (CV), and 4-AM and AC were simultaneously determined using differential pulse voltammetry (DPV). The oxidation process was irreversible over the pH rang studied and exhibited a diffusion-controlled behavior. To maximize the experimental conditions for simultaneous determination, the current's dependence on pH, concentration, and scan rate was examined. In some concentration ranges, the calibration graphs for both medications were linear.

References

Vealan, S.B.M.; Chinnathambi, S. Simultaneous determination of environmental endocrine disruptors bisphenol A and 4-nitrophenol bleached from food contacting materials using the spin-ladder compound La2Cu2O5 modified glassy carbon electrode, Chemosphere, 2024, 353, 141559.

Nour, M.M.; Tony, M.A. The Environmental Oxidation of Acetaminophen in Aqueous Media as an Emerging Pharmaceutical Pollutant Using a Chitosan Waste Based Magnetite Nanocomposite. Resources 2024, 13, 47.

Yao, M.; Fang, B.; Yang, J.; Sicen, W.; Fuchao, Ch. Simultaneous determination of 14 analgesics in postoperative analgesic solution by HPLC–DAD and LC–MS/MS. BMC Chemistry 2024, 18, 10.
Regulating and Concentrating Ion-Flux on Anode Materials for Next-Generation Batteries
Authors: Jeong Hyung Mo , Kim Donghyoung , Wang Benzhi , Kang Shin Joon , Kwon Sunhyeong , Song Byunggon
Published: December 2024

To meet the rising demand of energy density and power density for energy storage technology, advanced rechargeable batteries are needed to satisfy the energy issues. From this perspective, active material-free (anodeless or anode-free) design is considered as one of the most promising candidates for anodes due to the low redox potential and high theoretical capacity, leading a high power and energy density of full-cells. However, inevitable dendritic growth and limited electrochemical properties on anode sides are remained as the hindrance of practical application. To overcome this nature of anodes, structure-based self-ion (Li+) concentrating electrode with high reserve capacity and uniform ion-flux is suggested. Recent advanced researches demonstrate structural properties can activate the self-ion concentration and principle of ion control process is stimulated by the structure of electrode. Structural perspectives and electro-kinetic principle in electrode materials are considerable to be important factors impacting device performances by the ion-flux control of Li metal growth on anodes. In terms of electro-kinetic phenomena with porous structured and defect-rich media, Li+ is confined by nano scaled space and regulated by evenly distributed ion-affinitive sites in electrodes with electric field, and electrochemical reaction of this ion can be facilitated. In this presentation, regulating ion distribution on artificial layers consisting ordered ion-affinitive sites and concentrating local ion flux in the space confinement effects in beyond micropores consisting narrow slit will be presented as the major approaches for reaction control in electrodes of anode-free configuration. We hope that the method and applications demonstrated here could offer an opportunity to discuss ideas for designing the materials for high performance batteries.
Anodic Dissolution Behavior of Si Electrode in HF Solution Containing H2O2
Authors: Koketsu Daiki , Kato Shinya , Hoshi Yoshinao
Published: December 2024

Silicon is expected to be as anode materials for lithium-ion batteries because the battery performance can be improved by increasing surface area1). Metal-assisted chemical etching (MACE) 2) is a low-cost method to form the nano-silicon structures on Si electrode, which is called silicon nanowires (SiNWs). Though this method enables the fabrication of SiNWs to increase the surface area on Si electrode, the mechanisms on MACE have not been clarified yet. This study aimed to investigate the anodic dissolution behavior of Si electrode to understand the effect of electrolyte concentrations on MACE by electrochemical methods in the HF solution containing H2O2.

Electrochemical measurements were carried out by a three-electrode system. An electrochemical cell was made of a polypropylene (PP) to use HF as the electrolyte. The counter electrode was a platinum wire, and the reference electrode was a KCl-saturated Ag/AgCl electrode (SSE) fabricated by the polycarbonate that can be used in the HF solution. The Si, Ag, and Si with deposited Ag particles were used as working electrodes. The Si electrode was made from n-type silicon wafers with a (100) surface. The electrode of Si with deposited Ag particles was prepared using an electroless Ag plating. A mixture of HF and H2O2 was used as the electrolyte solution. To investigate MACE behavior, the measurements of the electrode potential, polarization curve, and electrochemical impedance were carried out at each electrode. The electrode potential of Si with deposited Ag particles was measured for arbitrary time in the electrolyte solution. The potentiostatic polarization of Si electrode was performed to investigate anodic dissolution behavior. The electrochemical impedance measurements were carried out with an AC potential amplitude of 10 mV at arbitrary DC potential. The frequency range was 100 kHz to 0.01 Hz at five frequencies per decade.

In the electrolyte solution of HF containing H2O2, the electrode potential of the Si with deposited Ag particles shifted to the less noble potential at the initial stage during MACE regardless of the concentrations of electrolyte solution. The cathodic polarization curve of Ag indicated that the cathodic reactions on Ag electrode were affected by the H2O2 concentrations. The anodic polarization curve of Si electrode demonstrated that the dissolution and film formation may occur on Si electrode, which was depended on the HF concentrations. Based on these results, the electrochemical impedance measurement was performed on the Si electrode. The dissolution and oxide film formation as the anodic reactions and the reduction reactions as the cathodic reactions during MACE were discussed to determine the suitable conditions for fabrication of SiNWs on the Si electrode.

References

Haibin Li, Shinya Kato, Yosuke Ishii, Yasuyoshi Kurokawa and Tetsuo Soga, Nano Ex., 3, 045010 (2023).

Ming-Liang Zhang et al, J. Phys. Chem. C, 112, 4444 (2008).
Bromine Enabled Selective Leaching of Li+ from Battery Cathode Active Material for Li-Ion Battery Recycling
Authors: Tuya Nathalie , Wang Zeyu , Stiber Alexandra , May Richard , Canzian Llanes Luana , Steingart Dan
Published: December 2024

To meet the growing demand for lithium ion batteries (LIBs) and to mitigate environmental impact from spent battery waste, efficient recycling processes are needed. Hydrometallurgy, the process by which valuable elements are separated and extracted from waste, offers promise but suffers from long leaching durations and high greenhouse gas emissions due to the production of chemicals used in these processes. One less explored option in the hydrometallurgy process is through selective leaching. Selective leaching, specifically of the Li-ion, would drastically reduce separation steps in the industrially common hydrometallurgical process.In this work, we demonstrate the selective leaching of lithium from NMC811 and LFP by leveraging Br2 as a leaching solution. Over 85% leaching efficiency for lithium is achieved in the Br2 leaching solution in just 30 minutes, while nickel, manganese, and cobalt achieve leaching efficiencies greater than 95% in under 30 minutes when using Br2 as an oxidizing agent alongside H2SO4. We also investigate the HBr/Br2 system as a leaching solution to enable Br2 circularity, finding similar selective leaching behavior with Li, but at lower efficiencies.
Magnetic Separation of Metal Ions Using Wet High-Gradient Magnetic Separation
Authors: Andrei Petru , Igboanugo Anthony , Brungi Pranathi , Carlstedt Nicholas
Published: December 2024

High-gradient magnetic separation (HGMS) traditionally has been used and currently is being employed commercially to separate ferromagnetic, ferrimagnetic and paramagnetic particles with radii over 100 nm. In this presentation we investigate the limits of HGMS for the separation of paramagnetic particles with radii below 100 nm, establish fundamental limits, and discuss possible practical approaches to design the separation system. In addition, we discuss the conditions required to separate metal ions in aqueous solutions. Compared to traditional techniques that use large amounts of chemicals, the magnetic separation of the metal ions is based on the difference between the magnetophoretic forces on ions with different values of the magnetic susceptibilities. The method is environmentally friendly and, depending on the implementation, can be very energy efficient.

In the first part of the presentation, we present the model equations that need to be solved to simulate the magnetic separation of metal ions in aqueous solutions. Then, we use these transport equations to simulate the magnetic separation process and predict and compare the efficiency of magnetic separation on HGMS systems with experimental data. The model considers the aqueous solution and the metal ions as two interpenetrating continua, which we call the solvent continuum and the magnetic particles continuum. The magnetic particles continuum interacts with the external magnetic field and moves through the non-solvent while experiencing a force of resistance similar to the model presented in [1]. The solvent continuum is non-magnetic. Both continua are inert and interact with neighboring elements of the same fluid by means of defined fluid pressure. More details about the mathematical model, underlying assumptions of the model, fundamental limitations, numerical implementation, simulation and experimental results will be presented at the meeting.

References:

[1] P. Andrei, N. Charlstedt, and P. Brungi, “Modeling of Magnetic Separation of Metal Ions in Aqueous Solutions,” to be published IEEE Trans. on Magn., (2024).
First-Principles Study of Photocatalytic Activity of Amorphous TiO2 Surface
Authors: Tamura Sota , Kato Motayasu , Tamura Tomoyuki , Honda Mitsuhiro
Published: December 2024

Photocatalysts are materials that exhibit many functions on their surface when they exposed to light, such as antifouling, air purification, deodorization, antibacterial, and water purification. Titanium oxide (TiO2) is known as a representative photocatalytic material because it is inexpensive and safe. It is expected to be a solution to recent energy and environmental pollution problems. Therefore, studies have been actively conducted to improve the catalytic activity.

Our group experimentally found that the catalytic activity of an amorphous TiO2 surface is approximately 13 times higher than that of a normal anatase crystalline surface. Therefore, it is considered that we can further improve the catalytic activity by controlling the surface structure. TEM-EELS has been widely used in recent years to observe nanoscale atomic arrangements and electronic structures with high spatial resolution. ELNES (electron energy-loss near-edge structures) spectrum obtained by EELS can provide sensitive information on chemical bonding, valence states and coordination. We observed the amorphous surface of TiO2 samples with high catalytic activity using the atomic resolution electron microscope (JEM-ARM200F @Nitech) and found that spectrum for the surface region were significantly different from those for bulk region. In this study, we aim to clarify the factors that increase the catalytic activity to propose materials with higher catalytic activity using first-principles calculations.

Amorphous surface models were generated by performing high-temperature melting, rapid cooling, and structural relaxation using first-principles MD (molecular dynamics) simulations with SIESTA code [1]. During the MD processes, the coordination number of Ti with oxygen in the amorphous surface region decreased, from 6 to 4 coordination. First-principles Ti L-edge ELNES calculations for the bulk crystalline region and the surface amorphous region were performed with QMAS code [2]. They reproduced the difference between experimental ELNES spectrum for bulk region and surface region well. Therefore, we indicate that the amorphous region of real materials is composed of 4-coordinated Ti. Furthermore, we investigate the reactivity of water molecules which is essential for photocatalytic reactions on the TiO2 surface and the influence of oxygen defects inside TiO2. We indicate unique characteristics of the amorphous surface to clarify the origin of highly active catalytic reactions.

References: [1] J. Solar et al., J. Phys. Cond. Matt. 14, 2745 (2000). [2] T. Tamura et al., Phys. Rev. B 85, 205210 (2012).

Figure 1
Lithium Metal Anode Using Polyacrylonitrile Supported Metal Nitrates As an Additive in Carbonate-Based Electrolyte
Authors: Kang Hyeonmuk , Moon Jung Hyeon , Cho Yeonbeom , Kang Heechan , Cho EunAe
Published: December 2024

As the demand for energy storage continues to rise, there is a growing need for research focused on developing high-energy-density and stable batteries. Among various anode materials for lithium batteries, lithium metal stands out as an ideal candidate due to its low redox potential and high specific capacity. Consequently, in the pursuit of post-lithium ion batteries with enhanced energy density, the utilization of lithium metal as an anode is inevitable. However, the stability and safety of lithium metal anodes are compromised by issues such as dendritic growth. When lithium metal comes into contact with organic electrolytes, it reacts to form a solid electrolyte interface (SEI). While the SEI prevents further electrolyte consumption, an unstable SEI layer can lead to uneven diffusion of lithium ions through the SEI and promote the growth of lithium dendrites. Therefore, achieving uniform lithium deposition and establishing a stable SEI is crucial for the safe operation of lithium metal batteries.

Lithium nitrate (LiNO3) is one of the promising electrolyte additives for Li metal anodes as reduction of LiNO3 forms a highly Li+ conductive lithium nitride (Li3N)-rich SEI. However, the application of nitrate additives in carbonate electrolyte has been limited due to poor solubility. Herein, metal nitrate (MNO3 = LiNO3, AgNO3, RbNO3) containing PAN interlayers are synthesized using electrospinning method and are adopted in cells using carbonate-based electrolyte. MNO3 containing polymer interlayer can release additive constantly enabling nitrate act as an electrolyte additive. Despite the expected role of Ag+ and Rb+ cations in enhancing Li deposition morphology, LiNO3 had the best cell performance. In the symmetric test, LiNO3/PAN had the longest cycle life of over 150 cycles whereas AgNO3/PAN and RbNO3/PAN lasted approximately 120 cycles. Furthermore, in full cell using NCM811 cathode, the cell with LiNO3/PAN show 90% retention after 100 cycles. Interestingly, in AgNO3/PAN cell, lithium nucleation overpotential disappeared and interfacial resistance alleviated only in earlier cycles but SEI composition was quite different from other samples probably due to Ag deposited on the Li anode. On the other hand, RbNO3/PAN cell show similar SEI composition and sufficient signs of NO3
- reduction, but non-reacting Rb+ is accumulated in the electrolyte and limit release of RbNO3 from the interlayer.
Role of Li Electrode Redox Potential and Solid Electrolyte Interphase (SEI) Species on the Coulombic Efficiency of LiFSI-DME and LiFSI-FEC Electrolytes
Authors: Wang Daniel , Plaza Rivera Christian Orlando , Iriawan Haldrian , Ceribelli Nicole , Giordano Livia , Shao-Horn Yang
Published: December 2024

Lithium metal is the ideal candidate to replace conventional carbonaceous anodes due to its high theoretical specific capacity of 3860 mAh/g and low negative thermodynamic potential of -3.040 V vs. SHE [1]. Most organic electrolytes are unstable in the presence of Li metal and are reduced to form a solid-electrolyte interphase (SEI). One strategy to mitigate electrolyte decomposition is by upshifting the Li electrode redox potential. Ko et al. report positive shifts of up to 0.6 V in the Li electrode potential can influence coulombic efficiency [2]. In recent years, LiFSI-DME and LiFSI-FEC electrolytes with different concentrations have demonstrated highly reversible Li metal plating and stripping coulombic efficiencies of up to 99.1% [3] and 99.64% [4], respectively. While Qian et al. and Suo et al. briefly commented on the increased amount of inorganic content in the SEI, LiFSI concentration’s role on Li metal redox potential and SEI composition remains unclear. Organic species at the Li anode/electrolyte interphase are measured using a recently developed in-situ FTIR method. Cell level performance is evaluated by measuring coulombic efficiency. Complimentary techniques such as NMR and Raman are used to learn about the solvation structure as well as inorganic and soluble electrolyte decomposition products [5]. Novel insight into the relationship between SEI species, Li redox potential, and coulombic efficiency are presented.

References

Cheng, Xin-Bing, et al. "Toward safe lithium metal anode in rechargeable batteries: a review." Chemical reviews 117.15 (2017): 10403-10473.

Ko, Seongjae, et al. "Electrode potential influences the reversibility of lithium-metal anodes." Nature Energy 7.12 (2022): 1217-1224.

Qian, Jiangfeng, et al. "High rate and stable cycling of lithium metal anode." Nature communications 6.1 (2015): 6362.

Suo, Liumin, et al. "Fluorine-donating electrolytes enable highly reversible 5-V-class Li metal batteries." Proceedings of the National Academy of Sciences 115.6 (2018): 1156-1161.

Hestenes, Julia C., et al. "Transition metal dissolution mechanisms and impacts on electronic conductivity in composite LiNi0. 5Mn1. 5O4 cathode films." ACS Materials Au 3.2 (2022): 88-101.
Designing a High-Energy Dry-Processed Electrode for Li-Ion Batteries By Layering Single-Walled Carbon Nanotubes Onto the Ni-Rich Cathode Material
Authors: Koo Jinkyo , Ha Chaeyeon , Seo Jae kwon , Kim Young Jun
Published: December 2024

With the growing need for lithium-ion batteries (LIBs) in the context of carbon-neutral policies, the requirements for high safety and high energy density in LIBs have gained importance. High-nickel-content (Ni≥90%) cathodes offer a means of increasing both volumetric and gravimetric energy densities, but they also increase the risk of structural instability, which jeopardizes the battery system's overall safety. Thus, it makes more sense to maximize electrode packing density while using stable cathode materials. To mitigate these issues, we apply a coating material of single walled carbon nanotubes (SWCNTs) on the surface of the LiNi0.85Mn0.07Co0.05Al0.03O2 cathode, thereby significantly increasing its electronic conductivity. Furthermore, to increase ionic conductivity of the SWCNT-coated NCMA cathode, we also adopted a solvent-free electrode fabrication procedure. Our SWCNT-dry electrode showed sustained electrochemical characteristics in addition to a notably high cathode material weight ratio (99. x (x=0.5, 0.7, 0.9) wt.%) and increased electrode density (4.0 g cm−3). Their superior volumetric capacity of 860 mAh cm−3 allowed them to surpass traditional wet-processed electrodes (The first group consists of NCMA, CB, and PVDF, mixed in a ratio of 96:2:2, achieving an electrode density ≈ 3.4 g cm−3 and second group consists of NCMA, CB, and PVDF, mixed in a ratio of 98:1:1 achieving an electrode density ≈ 3.6 g cm−3). SWCNT coating combined with a solvent-free electrode is a novel technique that could lead to significant improvements in LIBs' high energy density, industrial scalability, and cell safety.
Next Generation Electrolytes for High-Capacity Electrodes at Low Temperatures
Authors: Mennel Jason , Chidambaram Dev
Published: December 2024

Many electrodes used today in a range of different lithium-ion chemistries have reached the limit of their theoretical capacities. As energy storage demands are constantly increasing among a wide variety of applications, next generation electrodes are in dire need of commercialization. Although each with their own drawbacks, lithium metal and silicon are the most widely considered for use in next generation lithium-ion batteries as they both have over ten times the theoretical capacity as electrodes commonly used today. Lithium metal suffers from dendrite formation which short circuits the cell, and silicon suffers from excessive volume expansion which rapidly degrades the overall 3D structure. One area of unique specialization is lithium-ion batteries for Martian rovers, satellites, or even electric vehicles in colder climates. The added challenge of maintaining high capacity at low temperatures requires an understanding of the migration of lithium ions during discharge and the resistive processes at play. The liquid electrolyte is the most facile to manipulate and can decrease resistive processes along with enhance the migration of ions between lithium metal and the silicon electrode. This work combines the optimization of a copper modified silicon electrode, and lithium metal with an organic electrolyte that significantly improves the low temperature capacities of these next generation electrodes for long cycle life. With the combination of these electrodes and electrolyte, over five times the usual capacity of traditional electrodes has been demonstrated at -20°C for 250 cycles at reasonable discharge rates.
Segregating Primary Nanoparticles from Secondary Microparticles with Surface Coating-Networking Architecture for High-Voltage Cathode Life at High Rate
Authors: Palanisamy Manikandan , Mench Matthew M
Published: December 2024

Primary nanoparticles are segregated from secondary microparticles and surface modified with a polymer layer and conducting network for a durable high-voltage cathode at high rate. Secondary microparticles are synthesized using a Mn1.5Ni0.5(OH)2CO3 precursor, which undergoes thermal decomposition and calcination, releasing gaseous species of CO2 and H2O. In-situ high-temperature phase elucidation confirms the least degree of disordered phase spinel LiMn1.5Ni0.5O4 cathode without rock-salt impurity phase. Microscopic analyses reveal secondary microparticles and segregated primary nanoparticles with surface coating and conducting network architecture. Cyclic voltammograms of primary nanoparticles show well-resolved two redox peaks at 4.7 V compared to secondary microparticles. At 20 C discharge, primary nanoparticles exhibit a discharge flat voltage profile at 4.3 V and deliver a high reversible capacity of 100 mAh g–1 for the 12th cycle and 86 mAh g–1 for the 1000th cycle, while secondary microparticles deliver 70 mAh g–1 for 12th cycle and declined its cycle operation at 250th cycle with the capacity of < 5 mAh g–1. Production of LiMn1.5Ni0.5O4 cathode in this manner will limit instability in cycling while realizing the advantages of high energy density and operating voltage of LiMn1.5Ni0.5O4. Applications include EVs, e-VTOL aircraft, grid energy storage, and other high-voltage lithium-ion battery applications.

Figure 1
Development of Localized High-Concentration Electrolytes Containing DME Solvent for Long-Life and High-Power Lithium-Ion Batteries
Authors: Nakagawa Hirotaka , Aoyama Keigo
Published: December 2024

1.Introduction

We are promoting electrification towards carbon neutrality, since the evolution of batteries is indispensable, we are developing high energy, high power and long-life lithium-ion batteries.

While Ni-rich layered cathodes such as NCM811 have high capacity, the cycle life using NCM811 at high temperatures decrease. To overcome poor cycle performance, reported localized high concentration electrolytes (LHCE) which contains DMC solvent [1] was adapted to our chemical system and evaluated. Although better cycle performance at high temperature was observed, the resistance of cells using the LHCE should be lowered toward practical application.

In this study, the types and concentrations of solvents were investigated for long-life and high-power battery.

2.Experimental

The LiFSI salt concentration was set to 1.7 mol/L, and mixtures was prepared using 1,2-Dimethoxyethane (DME) and Ethylene carbonate (EC) as solvents, and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) as a diluent as shown in Figure 1 by weight ratio of solvents.

350mAh-class laminate cells were fabricated with NCM811 as the positive electrode active material and a mixture of silicon oxide and graphite as the negative electrode active material. The electrolyte amount was set to 11g/Ah. Resistance measurements were performed at 25°C with a SOC of 50%, applying a 10-second pulse from 0.2 to 2.5C for six points. Cycle tests were carried out at 60°C, charging at 0.3 C rate discharging at 0.8 C rate with cut-off voltage of 3.0-4.15 V.

３. Results and Discussion

The area specific DCR (ASD) and the absolute value of the slope of the capacity retention against the cumulative discharge energy were illustrated on the ternary diagram shown in Figure 2. The weight of EC to 15-20wt.% reduced ASD, and favorable cycle performances were obtained with a weight of TTE at 55wt.% or higher. By optimizing the electrolyte composition using DME, high-temperature cycle performance was improved by 3% and ASD resistance was reduced by 15% compared with reported LHCE using DMC which was shown as “ref” in Figure 2.

The effects of electrolyte compositions and the mechanisms for improving performance will be discussed based on data such as initial charging curves, energy levels of Li-FSI state by DFT calculation, coordination number of Li-FSI by molecular dynamics simulation.

*Since there was the potential risk of the corrosion on an aluminum current collector with our LHCE, investigations were conducted, and results were reported by our colleague.

References: [1] Xia Cao et al., J. Electrochem. Soc., 168, 010522 (2021)

Figure 1
Improvement of Sodium-Ion Conductivity in Sulfide Electrolytes for All-Solid-State Batteries
Authors: Hayashi Akitoshi , Motohashi Kota , Sakuda Atsushi
Published: December 2024

An important material for realizing all-solid-state batteries is a solid electrolyte with high ionic conductivity and excellent compatibility with positive and negative electrodes. Compared to lithium-ion conductors, sodium-ion conducting sulfides are expected to have the advantages of high conductivity and favorable ductility due to the weaker Lewis acidity of sodium ions [1].

Sulfide electrolytes with sodium-ion conductivity have been developed during the last decade. To achieve high ionic conductivity, it is effective to prepare glass electrolytes with high sodium content by the rapid-quenching or mechanochemical methods. Crystallization of glass electrolytes can enhance their conductivity by stabilizing a metastable crystalline phase in glass matrix. The conductivity of the Na3PS4 glass increased to 10−4 S cm−1 by crystallization [2]. We reported that the doping of sodium-ion vacancies in Na3SbS4 by partial substitution of W for Sb is effective in enhancing conductivity to the level of 10−1 S cm−1 [3,4]. Based on the high-temperature stability of sodium polysulfide melt, Na2.88Sb0.88W0.12S4 was synthesized directly from a stoichiometric mixture of Na2S, S, Sb and W by heating at ambient pressure followed by cooling [4].

Glassy Na3BS3 was also prepared by the same synthetic procedure under ambient pressure without the use of a vacuum-tight container [4]. The Na3BS3 glass showed better Na plating/stripping performance than Na3PS4 and is suitable for contact with negative electrodes [5]. Therefore, an all-solid-state cell was fabricated by using two types of solid electrolytes, Na3BS3 on the Na15Sn4 negative electrode and Na2.88Sb0.88W0.12S4 on the TiS2 positive electrode. The cell operated as a rechargeable battery at room temperature and maintained the coulombic efficiency of almost 100% from the 2nd to 300th cycles [4].

References

[1] A. Hayashi et al., Frontiers Energy Res., 4 (2016) 25.

[2] A. Hayashi et al., Nat.Commun., 3 (2012) 856.

[3] A. Hayashi et al, Nat.Commun., 10 (2019) 5266.

[4] A. Nasu et al., Energy Stor. Mater., 67 (2024) 103307.

[5] A. Nasu et al., ACS Appl. Mater. Interfaces, 14 (2022) 24480.