bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Numerical Simulation of Ohmic Impedance
Authors: Orazem Mark E.
Published: September 2023

Impedance spectroscopy measurements are often confounded by high-frequency phenomena associated with frequency-dependent ohmic resistance. Newman introduced the concept of frequency dispersion to account for the effect of the disk electrode geometry on the impedance response [1]. The phenomenon described by Newman in terms of frequency-dependent capacitance and ohmic resistance may be considered as an ohmic impedance, a transfer function associated with the resistance of the electrolyte to passage of current under the influence of geometry-induced (and frequency-dependent) non-uniform current and potential distributions [2].

Two kinds of models are described in the presentation. Finite-element models account for the influence of geometry on the impedance response for a disk electrode. These models demonstrate the ohmic impedance. The second model is an interpretation model used to extract properties from impedance data. For most cases, data are truncated to avoid being confounded by ohmic impedance. On rare instances, the ohmic impedance may be extracted by regression to data.

Gharbi et al. [3] suggested that the ohmic impedance follows the form of the Havriliak-Negami equation. The Havriliak-Negami equation was found to provide a good fit to the ohmic impedance calculated for different electrode geometries, including interdigitated electrodes [4] as well as disk electrodes [3].

The ohmic impedance was obtained by Levenberg-Marquardt regression of a process model that accounted for the ohmic impedance [5]. The experiments were performed using ferri/ferrocyanide redox species (10 mM each) in a 0.5 M KCl solution. The working electrode consisted of a 5-mm-diameter Au disk rotating at 800 rpm. A Pt gauze (4 cm2) was used as the counterelectrode, a saturated Ag/AgCl electrode was used as a reference electrode, and the temperature of double-walled electrochemical cell was held at 25 ±0.1°C.

The process model was expressed in terms of an ohmic impedance and an expression that accounted for the influence of a local constant-phase element on the faradaic reaction and the convective diffusion impedance, expressed in terms of a series expansion following the work of Tribollet and Newman [6]. Regressions were weighted by the experimentally determined error structure of the data, and the resulting parameters characteristic of the ohmic impedance were in excellent agreement with numerical simulations.

References

J. S. Newman, J. Electrochem. Soc., 117 (1970), 198.

V. Huang, V. Vivier, M. E. Orazem, N. Pébère, and B. Tribollet, J. Electrochem. Soc., 154 (2007), C81-C88.

O. Gharbi, A. Dizon, M. E. Orazem, M. T.T. Tran, B. Tribollet, and V. Vivier, Electrochim. Acta, 320 (2019), 134609.

A. Dizon and M. E. Orazem, Electrochim. Acta, 337 (2019), 135000.

W. Watson and M. E. Orazem, EIS: Measurement Model Program, ECSArXiv, 2020, https://ecsarxiv.org/kze9x/.

B. Tribollet and J. S. Newman, J. Electrochem. Soc., 130 (1983), 2016.
Degradation and Multi-Time-Scale State Estimation of Li-Ion Batteries in Satellites
Authors: Bolay Linda , Hosono Eiji , Sone Yoshitsugu , Latz Arnulf , Horstmann Birger
Published: September 2023

In-orbit satellite REIMEI, developed by the Japan Aerospace Exploration Agency (JAXA), has been relying on off-the-shelf Li-ion batteries since its launch in 2005 [1]. The performance and durability of Li-ion batteries is impacted by various degradation mechanisms, one of which is the growth of the solid-electrolyte interphase (SEI). Long-term SEI growth is the greatest contributor to capacity fade in lithium-ion batteries.

In this contribution, we will address several aspects of the modeling and simulation of the batteries of satellite REIMEI. We simulate long-term degradation under the generic LEO satellite cycling conditions in a P2D framework. The simulations are validated with experiments and in-flight data provided by JAXA [1]. Our group has developed models for long-term SEI growth [2,3]. To show the inhomogeneous growth of the SEI in 3D, we perform microstructure-resolved simulations [4].

These studies are the foundation for analyzing the states of the batteries, which cannot be measured in operando. To estimate the state of charge and state of health, we make use of filter techniques and the in-flight data of the satellite batteries. Kalman filters are particularly suitable for the noisy data. Since the states change on different timescales, a multi-time-scale algorithm is applied, where two filters are combined. With this approach, we aim to reliably predict the lifetime of satellite batteries in orbit.

References

[1] M. Uno, et al., J. Power Sources, 196(20) (2011) 8755–8763.

[2] F. Single, et al., ChemSusChem, 11(12) (2018) 1950–1955.

[3] L. von Kolzenberg, et al., ChemSusChem, 13(15) (2020) 3901–3910.

[4] L. Bolay, et al., J. Power Sources Advances, 14 (2022) 100083.
Predicting Oxygen Release and Surface Reconstructions in Li-Ion Battery Cathodes Via Automated Construction of Computational Surface Phase Diagrams and Machine Learning
Authors: Li Xinhao , Lam Wing-Chi Ashley , Yeu In Won , Mishra Abhiroop , Rodriguez Lopez Joaquin , Urban Alexander
Published: September 2023

Although LiNiO2 (LNO) is chemically very similar to LiCoO2 (LCO), LNO and related Co-free Ni-rich cathodes suffer from continuing surface degradation via oxygen gas release during electrochemical cycling that leads to the formation of surface phases with high impedance. While the surface degradation of LNO and related cathode compositions have been characterized experimentally on a phenomenological level, an understanding of the surface reconstructions that form on the atomic scale and the intrinsic surface instability of LNO compared with other related cathode compositions is still lacking.

To shed light on surface reactivity, we developed a thermodynamic methodology for the prediction of voltage and temperature-dependent surface electrode reconstructions [1] and a computational framework to automate the time-consuming enumeration of surface reconstructions, the construction of symmetric surface-slab models, and the analysis of surface phase diagrams [2]. By applying first-principles atomistic modeling, we determined the self-reduction mechanism of LNO and compared the stable surface reconstructions with those of LCO. To further assess the surface stability of more complicated NMC/NCA cathodes with the help of our own generated LNO and LCO databases, we developed a supervised machine learning (ML) model to train on geometrical and electronic fingerprints from surface and bulk models, respectively. Our results provide insight into the initial stages of surface degradation in Ni-rich cathodes and lay the foundation for the computational design of stable cathode materials against oxygen release.

Li, X.; Wang, Q.; Guo, H.; Artrith, N.; Urban, A. ACS Appl. Energy Mater. 2022, 5 (5), 5730–5741.

Li, X.; Qu, J.; Yeu, I.; Li, Z.; Rodríguez-López, J.; Urban, A., in preparation, 2023
Materials Graph Networks Assisting the Discovery of New Solid-State Electrolyte Materials
Authors: Duangdangchote Salatan , Voznyy Oleksandr
Published: September 2023

Finding novel solid-state electrolyte materials with specific desired properties is one of the main challenges of first principles-based modelling due to its high computational cost. Recently, machine learning (ML) has been used exclusively in the materials discovery field due to its remarkable capabilities to process large amounts of data and extract useful information insights. The implementation of ML into atomic-scale materials modeling can accelerated materials sampling with first principles accuracy, this should provide a short workflow and highly reduce the computational cost.

In this work, we facilitate the ML model that can effectively screen for targeted properties from the entire chemical database possibility, including those materials that have never been examined. Currently, we are developing a materials graph networks framework for representing periodic crystal systems with the capability to learn atomistic chemical insights, especially for the discovery of new solid-state electrolyte materials.

In this talk, we will discuss the basic theory and our recent work towards the development of ML model that can extensively discover and explore materials. We will highlight the computational-guided evolution approaches and screening high-performance Li conductor materials. Finally, we will end on discussing the future of ML-assisted materials discovery to the future of all-solid-state lithium batteries.
(Invited) First-Principles Electrochemistry Beyond Grand-Canonical DFT
Authors: Sundararaman Ravishankar
Published: September 2023

Electrochemistry underpins a significant share of modern energy conversion, energy storage and chemical synthesis technologies. Computational design of electrode, catalyst and electrolyte materials has primarily relied on approximate trends from first-principles density-functional theory calculations: the time and length scales involved in electrochemical processes are extremely challenging to capture in quantum-mechanical calculations. This leads to two key challenges on the path to first-principles electrochemistry: (1) including liquid and electrolyte distribution effects on reaction energetics, and (2) predicting correct charge states of reacting species adsorbed on electrode surfaces. To address these challenges, we incorporate classical statistical models of liquids and electrolytes within quantum simulations of electrochemical interfaces using joint density-functional theory. We have also developed grand-canonical electronic structure methods to realistically simulate electrochemical processes by automatically equilibrating charge states at a fixed electrochemical potential. After showcasing the need for such techniques with representative examples, I will point out open questions in the accuracy of both electronic structure and solvation effects, and introduce the BEAST collaboration targeting Beyond-DFT Electrochemistry with Accelerated and Solvated Techniques.
Understanding the Mechanism of Li-Mediated Nitrogen Reduction Reaction
Authors: Zhou Yuanyuan , Norskov Jens
Published: September 2023

Green ammonia production is a key environmental goal. As a crucial step towards this goal, a direct electrocatalytic N2reduction (eNRR) by protons and electrons emerges as a highly desirable alternative. However, all pragmatic attempts to develop such an electrochemical route have so far been hindered by invariably low selectivities and large overpotentials. The most reliable method presently is the lithium-mediated eNRR (LiNR) in non-aqueous electrolytes.1 Despite significant progress made to achieve high FE and current density2, 3,the mechanism of LiNR is yet not fully understood due to so many intricate processes involved ranging from the atomic scale to the macroscopic scale. Moreover, most Li-NRR studies have the limitations of using a sacrificial solvent as proton donors and difficulties in scaling up production in batch reactors. The talk will, address the long-term stability and high activity of PtAu in the HOR process by suppressing the unwanted THF oxidation and improving the tolerance towards CO-poison. Moreover, we investigate the mechanism of the LiNR from the ab initio atomistic reaction process, mean-field microkinetics, to the mass-transport simulations, explicitly achieving an improved understanding the dynamic change of the solid-electrolyte interphase in different LiNR reaction conditions and the effect on the performance.

Reference:

1 J. Choi et al, Nat. Commun.
11, 1–10 (2020)

2 K. Li, et al, Science 374, 1593-1597 (2021)

3 S. Li, et al, Joule, 6, 2083-2101 (2022)
Modeling of the Solid-Electrolyte Interphase: Transport Mechanisms and Mechanics
Authors: Köbbing Lukas , Latz Arnulf , Horstmann Birger
Published: September 2023

The solid-electrolyte interphase (SEI) considerably affects the performance and lifetime of lithium-ion batteries. Although the SEI has been investigated for many years, various central aspects of this thin passivation layer are still ambiguous due to its generic complexity. Therefore, we thoroughly investigate the growth mechanisms and the mechanical behavior of the SEI.

The long-term growth of the SEI is the main reason which determines the shelf-life of state-of-the-art lithium-ion batteries. Nonetheless, the relevant transport mechanism responsible for the continued growth of the SEI is still highly debated in the literature. Thus, we carefully compare the two mostly considered mechanisms, namely electron diffusion and solvent diffusion [1]. We investigate whether the two mechanisms can describe the observed state-of-charge (SOC) dependence and the typical square-root behavior in time for capacity loss during open-circuit battery storage. We demonstrate that the electron diffusion mechanism reproduces both the SOC dependence as well as the time dependence. Contrarily, we show that solvent diffusion can describe either the SOC dependence or the typical behavior in time. We demonstrate that there is no intermediate regime between the reaction-limited and the transport-limited regimes, which reproduces both dependencies at the same time. In addition, we examine the interdependence of the SOC and square-root time behavior of SEI growth. Due to self-discharge, the combination of both aspects leads to deviations from the typical square-root behavior in time. Our simulations of capacity fade account for this effect and reasonably match capacity fade experiments.

Another substantial aspect of lithium-ion battery research is the transition to next-generation anode materials. As a promising candidate with a high theoretical capacity, silicon receives a lot of research interest. Two major drawbacks of this material are the massive volume expansion and the observed open-circuit voltage hysteresis. Similar to graphite, the SEI covers silicon anodes and has to withstand the expansion and shrinkage of the anode during lithiation and delithiation [2]. We check whether the plasticity of the silicon particle will contribute substantially to the voltage hysteresis. Further, we examine the impact of stress and plastic deformations of the SEI on the volume expansion and the voltage hysteresis. We demonstrate that the mechanics of both silicon anode and SEI will determine the observed voltage hysteresis.

Köbbing, L.; Latz, A.; Horstmann, B. Preprint arXiv 2022, DOI: 10.48550/arXiv.2209.10854

Kolzenberg, L.; Latz, A.; Horstmann, B. Batter. Supercaps 2022, 5. DOI: 10.1002/batt.202100216

Figure 1
Investigation of the Co-Alloy Mechanism in the Multivalent Electrolyte on Si Anode by Finite-Element Simulation
Authors: Yang Zicheng , Cora Saida , Briselli Vincent , Sa Niya
Published: September 2023

Improvement of Si stability plays a critical role of development of the next generation anode for lithium-ion battery. It has been reported that the introduction of additional metal salts containing multivalent cations such as Mg2+ is shown to improve the stability of silicon for electrochemical cycling through the modification of the solid electrolyte Interphase (SEI). This work aims to understand the mechanism of the electrolyte role and its electrochemical effects for Si stability. We have built the electrochemical framework that combines the Newman P2D model with consideration of a dynamically altered electric field at the solid material to investigate the co-alloy mechanism of Si, Li and Mg.
In-Situ Raman Spectroscopy of Defined Copper Oxide Surfaces Formed by Electrochemically Controlled High-Temperature Oxidation
Authors: Stadt Michael Georg , Nelhiebel Michael , Larisegger Silvia , Fafilek Guenter
Published: September 2023

The oxidation processes of copper are of great importance since its occurrence leads to various problems, both in further processing and in operation of electronic devices and other technical applications. Extensive research on the thermal oxidation of copper has demonstrated that temperature and oxygen partial pressure affect the formation of oxides, oxidation rates and the chemical composition.

In this work powerful electrochemical methods for controlled oxidation are presented, where the oxygen partial pressure on the metal surface can be varied over a range of 10-25 to 100 bar in a single experiment. A specific arrangement of the setup extends its capabilities to enable in-situ Raman spectroscopy measurements of the produced oxide.

Controllable oxidation states are achieved in a solid-state electrochemical cell by polarizing a copper sample in contact with a single crystal of yttria-stabilized zirconia, which is conductive for oxygen ions at high temperatures. Optical transparency of the single crystal allows the Raman laser to pass through the crystal to measure the copper oxide formed on the copper-electrolyte interface.

Cyclic voltammograms contain kinetic and thermodynamic information about the oxidation processes. Thus, the various oxidation reactions are controlled by the potential that corresponds to the oxygen partial pressure, while the current measures the rate of layer growth as well as the thickness of the oxide layer. In situ Raman measurements allow more detailed analyses of the oxides. The combined data will be used to build a model for oxide layer growth, with particular attention to the defect chemistry of the copper oxide.
Potential Dependent Evolution of Electric Double Layer at Electrode/Water Interface
Authors: Zhao Fujia , Zhang Yingjie
Published: September 2023

Water structure at electrode interface can affect electrochemical reactions in multiple ways, as it plays important role in processes including mass transport, surface adsorption, and charge transfer. Thus, in-situ characterization of electrode/water interface is in high demand for a deeper understanding and better utilization of electrochemical systems. Here, we introduce our study on the evolution of interfacial water structure with changing electric potential. Configurational and structural understanding were obtained by in-situ Raman spectroscopy and atomic force microscopy (AFM) measurements respectively, with special efforts to enhance interfacial sensitivity for both techniques. Our study demonstrated electric potential dependent changes in the hydrogen bonding network and hydration layer structure, which provides new insight into how interfacial hydration structure can be correlated with the electrochemical reaction performance.
Relating Selective Electrochemical Nitrate Reduction to Electronic Structure by AP-XPS
Authors: Stoerzinger Kelsey A , Carvalho Quinn Quinn , Crumlin Ethan J.
Published: September 2023

Ammonia produced by the Haber-Bosch process fixes nitrogen by sourcing hydrogen from methane steam reforming—today’s most carbon intensive industrial process. Alternatively, ammonia can be produced electrochemically from industrial waste nitrogen sources (e.g. nitric oxides, and nitrate), sourcing protons from water and electrons as reducing agents. However, reduction of such oxidized nitrogen species involves complex reaction mechanisms where the stability of critical reaction intermediates (e.g. nitric oxide) dictates selectivity towards ammonia as a final product. Inspired by Hammer and Nørskov’s d-band theory, we utilize synchrotron-based ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) to explore the adsorption affinity, and ability of a surface to dissociate, nitric oxide for a series of transition metals (Fe, Co, Ni, Cu). Nitric oxide adsorption affinity and dissociation are then linked to transition metal electronic structure and contextualized further with ex-situ electrochemical selectivity measurements and density functional theory (DFT) calculations.
Probing Lattice Oxygen Oxidation in Perovskite Electrocatalysts By Resonant Inelastic X-Ray Scattering
Authors: Bosse Jan , Akbashev Andrew
Published: September 2023

During water electrolysis, the hydrogen evolution reaction that generates hydrogen gas is unavoidably accompanied by the anodic reaction that generates oxygen via the oxygen evolution reaction (OER). However, under OER conditions, many electrocatalysts undergo structural degradation and can become amorphous. Lattice oxygen oxidation was proposed as one of the possible causes for amorphization of perovskite oxides. However, because lattice oxygen oxidation is notoriously challenging to probe in experiments, its unambiguous detection in oxide electrocatalysts has been elusive so far.

Here, I will show how oxygen oxidation can be detected in single-crystalline (model) oxide electrocatalysts using high-resolution resonant inelastic X-ray scattering (RIXS). Specifically, I will present our case study of perovskite materials where the emergence of oxidized oxygen depends on the transition metal and the applied potential. An insight into the chemical environment of the oxidized oxygen and how it can be accommodated in the perovskite lattice will be provided based on the results of DFT and molecular dynamics. Finally, I will discuss how lattice oxygen oxidation is related to the degradation of oxide electrocatalysts during OER.
Topology Optimization of Prelithiated Sio for Improving Dimensional Stability
Authors: Kim Ji Young , Youn Donghan , Jeong Won Joon , Kim Soohwan , Ma Donghyeok , Lee Tae Rim , Kim Seung Tae , Kim Hansu
Published: September 2023

As the demand for high energy density materials of lithium ion batteries increases, silicon monoxide is considered one of the promising anode materials that can replace the conventional anode materials. However, the low initial Coulombic efficiency(ICE) and the poor cycle stability bottlenecks the commercialization of SiO material. Although numerous efforts have been made, these two chronic issues of SiO have not been solved simultaneously. Here, we demonstrated a prelithiation method to improve the ICE as well as cycle ability by optimizing the topology of prelithiated SiO. Calorimetric method and LA-APT analysis revealed that four exothermic reactions are related with the topology and microstructure of prelithiated SiO. At the optimum heat treatment temperature of 650 ℃, the prelithiated SiO showed a capacity of 1164 mAh g-1 with an ICE of 89.6 % and a remarkable capacity retention of 73.4 % at 300 cycles. We also found that the optimized electrode expanded less compared to non-optimized prelithiated SiO materials. The outstanding electrochemical properties were attributed to the modulated topological arrangement of the active Si phase and Li2SiO3 inactive buffer phase. Further description of the topological optimization will be discussed in the presentation.
Ultrathin, Smooth Li-Metal Anode Via Electrodeposition for Stable Cycling of Li-Betal Batteries Under Practical Conditions
Authors: Seo Jiyeon , Lim Minhong , Lee Hongkyung
Published: September 2023

Lithium (Li) metal anodes (LMAs) with high specific capacity (3860 mAh g–1) and lowest redox voltage (–3.04 V vs SHE) are considered superlative candidates for high energy batteries. Ultra-thin, large-area LMA is crucial for building Li-metal batteries (LMBs) that can deliver high volumetric and gravimetric energy density in practice. As the charging and discharging continue, the growth of Li dendrite is regarded as one of the significant challenges. The surface nature of LMAs is the main aspect of Li dendrite formation and interface reaction. However, most studies overlooked the initial condition of LMA surface. Native passivation layer (NPL) of commercial Li foils is inherently uneven composed of Li2CO3, LiOH, and Li2O, and its chemical nature is mostly determined under manufacturing conditions. Incomplete passivation at an initial stage can trigger sporadic Li dendrite growth and chemical/structural deterioration of LMAs, adversely affecting the cycling stability of LMBs.

This work presents the electrochemical pre-passivation to build an electrolyte-derived native layer (electro-native layer, E-NPL) through Li electrodeposition method. Electrodeposited LMA (ed-LMA) was prepared by pre-deposition at the Cu foil using localized high-concentration electrolyte (LHCE) and post calendaring for smooth LMA surface. As-prepared ed-LMA has 4.13 mAh cm-2 of areal capacity with ~22 µm, and reduced roughness, which is much lower than that of manufactured LMA (m-LMA). Particularly, the E-NPL derived by LHCE can tailor the LMA surface by enriching the inorganic SEI compounds such as LiF, and N-SOx. In addition, decreased amount of passivated components such as Li2CO3, LiOH, and hydroxide were found in XPS analysis of the anodes. Compared to manufactured LMA (m-LMA), the ed-LMA exhibited lower overpotential for Li plating/stripping cycles and enhanced capacity retention. Benefiting from better compatibility with newly plated Li, it showed higher plating density without electric isolation from beneath Li surface, mitigating the anode swelling during subsequent cycling. We successfully demonstrated battery cycling stability of Li||NMC622 cells exploiting ed-LMA (195 cycle at 80% retention), superior to m-LMA (110 cycle at 80% retention) under stringent conditions.
Voltammetric Detection of Explosive Nitroaromatic Compounds Using Boron-Doped Carbon Nanowall Electrodes
Authors: Dettlaff Anna , Kaczmarzyk Iwona , Sobaszek Michal , Prasuła Piotr
Published: September 2023

Nitroaromatic highly energetic explosive compounds were widely used during the I and II World Wars. Some of them, like 2,4,6-trinitrotoluene (TNT), are still used in military munitions or in industrial applications i.e., underwater blasting, mining, deep well or dye production. The worldwide use of nitroaromatic compounds led to widespread pollution of the environment causing a danger to living organisms due to their high toxicity and possible carcinogenicity. The most commonly used techniques for the detection of explosive nitroaromatics are high-performance liquid chromatography or high-resolution gas chromatography coupled with different detectors like mass spectrometers. Both methods require: expensive instrumentation, complex sample preparation which is crucial to analysis, and well-trained staff to perform the experiments. Therefore it is difficult to implement chromatography in the field. Electrochemical sensing is emerging as a fast, sensitive and relatively simple technique for detecting explosive materials. To date, various materials have been used as working electrodes for this purpose, however, carbon materials are particularly promising [1-2]. Among carbonaceous materials, boron-doped carbon nanowall (B:CNW) electrodes are particularly attractive for the sensitive and rapid detection of nitro-based compounds [3] due to the high content of sp2 phase, wide electrochemical working potential window (from -1.6 V to 1.2 V in 0.5 M KCl) and high values of heterogeneous electron transfer rate constant.

In this work, we present electrochemical detection of chosen nitroaromatic explosive compounds like TNT on boron-doped carbon nanowall electrodes in aqueous solutions using voltammetric electrochemical techniques (differential pulse voltammetry, square-wave voltammetry, cyclic voltammetry). B:CNW electrodes were obtained using microwave plasma-assisted chemical vapour deposition in a one-step growth process. B:CNW electrode show enhanced electrocatalytic activity towards nitro moieties attached to aromatic rings, resulting in improved sensitivity toward detecting these groups. Hence, it is an attractive nanocarbon surface for nitroaromatic compound determination.

References

[1] M. Goh et al., Anal Bioanal Chem 2011, 399, 127–131. Doi: 10.1007/s00216-010-4338-8

[2] A. Dettlaff et. al, Microchimica Acta, 2022, 189:270. Doi: 10.1007/s00604-022-05371-w

[3] A. Dettlaff et al., J. Hazard. Mater. 2020, 387, 121672. Doi: 10.1016/j.jhazmat.2019.121672

Acknowledgements

The research leading to these results has received funding from the Norway Grants 2014-2021 via the National Centre for Research and Development within research grant no. NOR/SGS/NITROsens/0011/2020-00
Detection of H2O2 using Carbon Nanotubes Covalently Attached to Nanostructured Au Electrode
Authors: Huseinov Artur , Nawarathne Chaminda P , Alvarez Noe T
Published: September 2023

Detection of hydrogen peroxide (H2O2) has practical significance in various fields, including pharmaceutical, clinical and food industries. The enzyme based H2O2 biosensors allow for the detection at lower potentials, thus avoiding possible interference from reducing agents. However, this type of sensors is inherently less stable, difficult to fabricate and more expensive. Due to high electroactive surface area and electrocatalytic properties, gold nanoparticles and their combination with carbon nanotubes (CNTs) are commonly used in H2O2 sensor design.

To avoid fabrication inconveniences and improve stability of a H2O2 sensor, we designed a new hybrid material in which CNTs are covalently attached to a gold surface. First, a highly homogeneous nanostructured gold surface was formed on top of the SiO2 substrate with an intermediate layer of Ti, using E-beam evaporation technique. The average height of the gold nanostructures was 3.9 nm. The gold surface was then electrochemically grafted with aminophenyl groups. Further, plasma-functionalized densified CNT film made from CNT array was attached to the gold surface via amide formation reaction. An introduction of CNTs led to a 40-fold increase in current response. Formation of nanostructured gold surface without actual attachment of nanoparticles to the substrate, as well as covalent bonding of CNTs to the surface, provide a very high stability of the fabricated material, which, in turn, improves the repeatability of measurements.

A designed electrode was used for non-enzymatic H2O2 detection. Under optimized parameters of square wave voltammetry and optimum pH, analysis of H2O2 can be performed using 5 independent oxidation peaks. The presence of multiple peaks is due to oxidation of gold, CNTs and H2O2 itself. All peaks increase when H2O2 is added in solution, because of chemical reduction of CNT and gold surfaces, and their consecutive electrochemical oxidation. Using the peak at -0.6 V allows for the H2O2 detection at very low potential, that can minimize interference from various reducing agents. For the -0.6 V peak, the limit of detection was 1.4 mM. Using the peak at -0.05 V allows for much higher sensitivity with the limit of detection of 500 nM.

Almost no signal deterioration was observed after 200 measurements, proving high stability of the fabricated electrodes.
Lead Scale from a Lead Pipe Detected Using Electrochemical Methods
Authors: Dangel Gabrielle R. , Dominique Emily G , Nawarathne Chaminda P , Hoque Md Abdul , Huseinov Artur , Alvarez Noe T
Published: September 2023

Electrochemical methods, such as square wave voltammetry, can detect lead in drinking water. However, these methods can only detect lead ions. Lead contamination in drinking water can be from both Pb2+ and particulate lead. Particulate lead comes from the inner walls of lead pipes and is often called lead scale. Lead scales forms from years of water with varying parameters such as pH, alkalinity, and disinfectants flowing through the pipes. The lead scale used in this work was collected from a lead pipe used in Cincinnati, Ohio. Characterization using x-ray powder diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDS) showed lead carbonate and lead oxides within the scale. These lead compounds are insoluble in drinking water which can have a pH between 7 and 9; however, if the pH is lowered to below pH 2, these lead compounds have an increased solubility. This work uses membrane electrolysis (ME) to acidify a tap water solution containing lead scale. The standard addition method is then used to collect a standard addition curve, then the unknown lead concentration from the lead scale can be calculated. Inductively coupled plasma mass spectroscopy (ICP-MS) was used as a standard method to compare the SWV results to the actual amount of lead within the unknown sample.
Nanoelectrochemistry of Metal Dissolution and Deposition Reactions
Authors: Ren Hang , Wang Yufei , Lee Heekwon
Published: September 2023

Electrochemical metal dissolution and depositions reactions are reversible processes involving phase transition, which are fundamentally important in battery and corrosion. The electrode kinetics of these reactions are highly sensitive to the surface structures. In this talk, I will present the study on the initiation of metal dissolution reactions on Ag and Ni, representing model systems for oxide-free and oxide-covered metals, respectively. The local dissolution kinetics is voltammetrically mapped via scanning electrochemical cell microscopy (SECCM). Co-localized characterization of crystal orientation reveals slower dissolution on {111} close-packed planes. Direct measurement of local dissolution kinetics on grain boundaries shows a faster dissolution rate on some but not all grain boundaries. We demonstrate that correlative electrochemical and structural imaging are powerful tools for studying heterogeneity at complex electrochemical interfaces, which can also be used to study metal deposition reactions at the nanoscale.
Light Addressable Electroanalysis with Semiconductor/Metal Junctions
Authors: O'Neil Glen D
Published: September 2023

Light addressable electrochemical sensing (LAES) is a photoelectrochemical sensing technique that uses light to activate a faradaic electrochemical reaction at the surface of a semiconducting photoelectrode. Using LAES we can confine an electrochemical reaction to a microscopic portion of a macroelectrode using focused illumination, enabling photoelectrochemical imaging of biological processes. LAE sensors use semiconductors as the light-absorbing electrode material, and as a result understanding and controlling the electrochemical response of these sensors is considerably more challenging than with metallic electrodes. These challenges are due to the nature of the band structure of the semiconductor, the interfaces between the semiconductor/electrolyte, and the nature of charge transfer across these interfaces. Moreover, when silicon is used as the electrode material, steps must be taken to protect the sensor from corrosion in aqueous electrolytes.

Here we present recent results from our group showcasing semiconductor/metal junctions as LAE sensors. We show that Schottky junctions formed between nSi and Au, Pt, or Ni nanoparticles are excellent candidates for LAE sensors. These junctions can be prepared with a simple benchtop electrodeposition procedure and demonstrate excellent electrochemical properties with near-reversible cyclic voltammetry observed with a number of outer-sphere redox couples. We apply these sensors to the detection of sub-µM concentrations of neurotransmitters and other biologically relevant species (e.g., H2O2). We will also show how alternative voltammetric waveforms can be used to provide richer electrochemical information about the interface and increase sensitivity of the sensors.
Influence of Frictional Heat on Hydrogen Permeation Measurements
Authors: Reinbold Jasmin , Boiadjieva-Scherzer Tzvetanka , Stache Heiko , Vengudusamy Balasubramaniam , Fafilek Guenter
Published: September 2023

Hydrogen transport properties in metals are often investigated in electrochemical Devanathan-Stachurski double cells (DS) or modifications thereof. A DS setup consists of input and output cells which are divided by a metal membrane. The hydrogen oxidation current measured in the output cell is proportional to the permeation rate of hydrogen through the metal membrane. In certain applications of lubricated tribocontacts, steel is susceptible to damages by uptake of hydrogen. For investigation of the friction-generated hydrogen uptake a lubricated sliding contact in the input cell of the DS setup is realized.

Related low hydrogen permeation current signals are significantly affected by the steel membrane temperature. As an example, frictional heating of the steel membrane leads to additional release of residual hydrogen from the steel. To investigate the temperature effect, tests with an oil containing a hydrogen promotor, a PFPE oil and without lubrication were conducted. The results indicate that the permeation signal is strongly influenced by frictional heating. Such measured currents must not be misinterpreted as hydrogen generated by lubricants. A thermodynamic and kinetic model of the hydrogen diffusion and trapping reveals the correlation between current signal and temperature change.
Demystifying the Asymmetry in Lithiation/Delithiation Behaviors of Silicon Anodes for Lithium-Ion Batteries
Authors: Lu Peilin , Fritz Nathan Joseph , Sun Shijie , Park Jaehong , Braun Paul V.
Published: September 2023

One critical factor that impedes the wide adoption of electric vehicles is the charging time, which is considerably longer when compared to the refuel time of internal combustion vehicles. To shorten the charging time to less than 6 minutes, extremely fast charging (XFC) of more than 10C is required. In recent years, silicon was regarded as a promising candidate for fast charging because it has a high energy density and is less prone to lithium dendrite growth. However, existing Silicon technologies have not surpassed the 6-minute charging goal. Here, we discuss the possibility for XFC of a three-dimensionally engineered electrically conductive porous Ni/Si composite anode. This anode structure can effectively alleviate the huge volume change upon cycling and provide a pathway for fast electron and ion conduction. Although it shows excellent delithiation (discharging) rate capabilities when coupled with an optimized electrolyte, the lithiation capacity is severely limited at higher C-rates. To study the asymmetry in lithiation/delithiation and the mechanism of relatively sluggish lithiation, we performed rate performance test, Galvanostatic Intermittent Titration Technique (GITT) and Direct Current Electrochemical Impedance Spectroscopy (DCEIS). Based on our findings, we propose the potential rate limiting step for lithiation, which is believed to improve the charging rates substantially when overcome.
Strategies on Enabling High Areal Sulfur Loading in Lithium Sulfur Batteries
Authors: Motevalian Saeme , Nazir Aqsa , Claus Ana , Jahan Georgina , Hamal Dambar , Awadallah Osama , El-Zahab Bilal
Published: September 2023

Needs for energy storage devices in modern-day applications such as electric vehicles and other high energy consuming portable electronics make the Lithium sulfur batteries (LSBs) to be one of the most attractive types since they offer a high theoretical energy density (2600 Wh kg-1), which is about an order of magnitude higher than the theoretical specific capacity of the lithium ion batteries. In addition, Sulfur is one of the most abundant materials in nature and moreover, a non-toxic element which makes the lithium sulfur battery a suitable candidate for commercialization. However, obstacles to overcome include the loss of active sulfur due to various phenomena mainly represented by polysulfide diffusion and reactivity on the lithium anode. Another serious issue observed in so many ways is the low electronic conductivity of Sulfur and its products such as Li2S as a result of cycling. These problems are often exacerbated at higher sulfur loading and lower electrolyte to sulfur ratios (E/S). One way to increase the sulfur loading is to increase the thickness of the cathode which in return increases the risk of low utilization of active material because of the high thickness and low wettability by electrolyte. Another way is to increases the ratio of the sulfur in respect to conductive host material without increasing the thickness of the cathode. By doing so, sulfur is going to fill all the pores existing in the host material and therefore, this structure cannot provide enough volume expansion during discharge process and as a result, the cathode structure may collapse and the whole cell fail. Therefore, to come up with a high performance and stable battery during cycling, there is no doubt that we have to focus on the structure of the cathode and the host material to effectively confine the sulfur and produced polysulfide and at the same time, alleviate the way of the electron transfer through the conductive network.

In this research, we investigate some of the most influential parameters mainly associated with the morphology of the cathode to improve capacity retention. Optimizing the sulfur loading, E/S content, pore structure and pore volume, and the thickness of the cathode lead to an overarching understanding of the physical transitions that occur during the discharge and charge operation of the battery. In addition, various electrochemical testing to evaluation the loss of activity of the cathode surface is also carried it to correlate to the proposed physical model.
Electrochemical Response of Alkaline Batteries Subject to Quasi-Static and Dynamic Loading
Authors: Gober Megan , Barnes Baxter , O'Donoghue William , Mayeur Jason , Hazeli Kavan , Nelson George J.
Published: September 2023

Electrochemical changes were successfully monitored through the coupling of external loading, electrochemical impedance spectroscopy (EIS), and distribution of relaxation times (DRT) analysis. The development of the testing methods allows for detailed observation of changes due to mechanical loading and distinguishes responses between different cell geometries. Comparison of the force versus displacement, voltage versus displacement, and distribution of relaxation times plots to the different cell geometries display failure modes specific to geometry as well as the impact of different loading profiles. Numerical modeling confirmed the movement within individual cells and predicted locations with the most deformation based on the external loading condition applied. The results gathered from combining mechanical loading, electrochemical response, and numerical modeling, yield a viable approach to establishing an improved understanding of the effects of mechanical loading on the electrochemical response of multiple battery geometries and the methods herein may be extensible to additional battery chemistries.
Nanoscale Lithium Distribution within a Secondary Cathode Particle for Li-Ion Battery Using Identical Location (S)TEM-EELS
Authors: Birnbach Martin , Karan Naba , Jankovic Jasna
Published: September 2023

Energy density of LIBs are primarily limited by cathodes and further development of cathode materials requires in-depth understanding of the structural and compositional changes spanning across various length scales involved during electrochemical delithiation/lithiaton. Cathode materials are usually synthesized as secondary particles (∼10 µm) that are sintered agglomerates of smaller primary particles (∼100s µm). Lithium distribution may not necessarily be uniform across the entirety of these particles in typical state-of-the-art layered cathodes during electrochemical cycling. A detailed knowledge of lithium distribution within secondary particles is crucially important for obtaining a comprehensive understanding of the energy storage system. To truly understand the structural changes taking place at the nano and atomic scales, high spatial resolution techniques are of paramount importance for understanding the lithium distribution and optimizing/developing future LIB cathodes. STEM-EELS is ideally suited for obtaining such information at the desired (atomic) spatial resolution. In the present work, nanoscale lithium-ion distribution was investigated among various primary particles within a secondary particle of state-of-the-art Ni-rich layered LIB cathode using identical location scanning transmission electron microscopy with electron energy loss spectroscopy (IL-STEM-EELS) by making use of a specially designed electrochemical cell employing TEM grids. Identical location allows for the imaging of the same location before and after electrochemical testing to evaluate localized changes. Nanoscale lithium-ion distribution along with the electron beam dose effects on the nanoscale/atomic structure of layered NMC532 cathodes at various charge stages will be presented.
Physics Based Temperature Dependent EIS Simulation on 18650 NMC/Graphite Cell
Authors: Civan Fazlı Eren , Katırcı Gökberk , Ülgüt Burak
Published: September 2023

Electrochemical Impedance Spectroscopy (EIS) is a non-destructive method that provides crucial insights regarding the battery processes. EIS is mainly done by applying a small amplitude AC with a 10 mHz to 1 MHz frequency range. One can determine the electrolyte's ohmic resistance, the Solid Electrolyte Interface (SEI) capacitance, electron transfer rate and the diffusion mechanisms at separate frequency regions from each other.

One disadvantage of EIS is the ambiguity of the analyses of the data. The equivalent circuit models used are not unique, and the correspondence between the various elements in the equivalent circuits to electrochemical phenomena are suspect. A new approach on EIS analysis is sought after in order to improve the interpretation. For example, distribution of relaxation times (DRT) was proposed by Zhang et al. in 2015 .

Using physics-based models in order to model EIS has been published by Murbach and Schwartz in 2018. In their work, they created a physics-based simulation which uses a pseudo two-dimensional battery model. Their main aim was to present a new approach to EIS data analysis by using a physics-based model rather than equivalent circuit models. They created a data set with 38.800 separate spectra and match the experimental data by using least squares matching approach with the previously computed data. Though this work improved the understanding, multiple calculated data sets matched the experiments with similar errors.

Ultimately, in order to achieve an EIS analysis method that is directly related to the fundamental parameters regarding the electrochemistry, degeneracies have to be removed via temperature dependence and the non-linearities as extra dependent variables. This way, the ambiguities and the suspicious parameter assigning can be fixed.

We will be reporting on T-dependent linear and nonlinear simulations on 18650 NMC/Graphite battery. All the simulations were done on Python by using a physics-based model PyBaMM (Sulzer, Valentin, et al. "Python battery mathematical modelling (PyBaMM)." Journal of Open Research Software 9.1 (2021).). Impedance data was obtained via simulating voltage as a function of current within 100 µHz to 10 kHz frequency range. Temperature range was set to -25°C to 65°C with 10°C increments. The linear and non-linear impedance is analyzed as a function of temperature. Our results will be compared with experimental temperature dependent linear/nonlinear spectra in order to obtain proper fundamental parameters