Ezequiel Pedro Marcos Leiva

Ezequiel Pedro Marcos Leiva
National University of Córdoba | UNC · Department of Mathematics and Physics

About

261
Publications
30,499
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
4,471
Citations
Additional affiliations
January 2000 - December 2012
National University of Córdoba
Position
  • Universidad Nacional de Córdoba (Argentina)
January 1995 - present
Ulm University
January 1988 - present
University of Bonn

Publications

Publications (261)
Article
In this work, we evaluate the reliability of a recently developed model for estimating kinetic parameters for different materials used in lithium-ion batteries. This model considers non-interacting Li-ions being inserted under constant current conditions, assuming finite diffusion inside the particles and charge transfer limitations at the electrod...
Article
Full-text available
Anode-free metal batteries (AFMBs) are a new architecture of battery technology that relies solely on current collectors (CCs) at the anode side, eliminating the need for traditional metal anodes. This...
Article
Silicon anodes hold great promise for next-generation Li-ion batteries. The main obstacle to exploiting their high performance is the challenge of linking experimental observations to atomic structures due to the amorphous nature of Li-Si alloys. We unveil the atomistic-scale structures of amorphous Li-Si using our recently developed density functi...
Article
Full-text available
Capacity retention is a critical property to enhance in electrochemical storage systems applied to renewable energy. In lithium-sulfur (Li-S) batteries, the capacity fade resulting from the shuttle effect of polysulfides is a major obstacle to their practical application. Sepiolite, an eco-friendly earth-abundant clay with suitable surface chemistr...
Preprint
Full-text available
We present a new approach to studying nanoparticle collisions using Density Functional based Tight Binding (DFTB). A novel DFTB parameterisation has been developed to study the collision process of Sn and Si nanoparticles (NPs) using Molecular Dynamics (MD). While bulk structures were used as training sets, we show that our model is able to accurat...
Article
Fast charging is one of the most important features to be accomplished for the improvement of electric vehicles. In the search for optimal use of active materials for this aim, we present a recipe to find the conditions for fast charging, fifteen minutes for 80 % of the State-of-Charge, of lithium-ion battery's single particle electrodes, thus taki...
Preprint
Full-text available
The predictive power of molecular dynamic simulations is mainly restricted by the time scale and model accuracy. Many systems of current relevance are of such complexity that requires addressing both issues simultaneously. This is the case of silicon electrodes in Li-ion batteries, where different Li$_x$Si alloys are formed during charge/discharge...
Article
Full-text available
In this work, we develop a new tool to provide a diagnostic map for alkali‐ion intercalation materials under galvanostatic conditions. These representations, stated in the form of capacity level diagrams, are built from hundreds of numerical simulations representing different experimental conditions, summarized in two dimensionless parameters: a ki...
Article
Full-text available
Shedding light onto the processes that limit the fast charging of alkali-ion battery cells constitutes a hotspot area. In the present work, we study two of the most important ones at the microscopic level: charge transfer at the interface and diffusion of ions inside the electrodes, focusing on how the geometry of particles regulates these kinetic...
Article
Beyond Li-ion batteries, one of the most promising technology is the Lithium-Sulphur (Li-S) not only for its higher theoretical energy density (about 2600 Wh kg⁻¹) but because sulfur is relatively inexpensive and non-toxic. However, the Li-S battery suffers from “shuttle effect” of polysulfides. Thus, restricting shuttling means increasing cell per...
Article
Full-text available
Here, we report on a novel study for battery application regarding the impact of interactions in charge transfer and diffusional features in finite-size systems. An easy way to represent these features is the construction of a map called zone diagram for voltammetry simulations, where different domains are related with a characteristic charge trans...
Article
Full-text available
Since 1994, Kinetic Monte Carlo (kMC) has been applied to the study of Li-ion batteries and has demonstrated to be a remarkable simulation tool to properly describe the physicochemical processes involved, on the atomistic scale and over long time scales. With the growth of computing power and the widespread use of lithium-based storage systems, mor...
Article
Full-text available
Motivated by the abundant experimental work in the area of Li-ion batteries, in the present work we characterize via computer simulations the structure of Si-Li amorphous alloys in a wide range of compositions. Using a reactive force field we propose a novel accelerated exploration of local minima to obtain amorphous structures close to equilibrium...
Article
Full-text available
Lithium-sulfur batteries are considered one of the possible next-generation energy-storage solutions, but to be commercially available many drawbacks have yet to be solved. One solution with great potentiality is the use of lithium sulfide as cathode material since it can be coupled to Li-free anodes, such as graphite, Si or Sn. Nevertheless, Li2S,...
Article
The interaction of polysulfides with oxidized graphene layers containing functional groups (hydroxyl, epoxy and carboxyl groups) is analyzed using first-principles calculations, with the aim of using these structures to prevent polysulfide migration in lithium-sulfur batteries. An estimation of the residence time of the polysulfide on the oxidized...
Article
Complex materials composed of two and three elements with high Li-ion storage capacity are investigated and tested as lithium-ion batteries (LiBs) negative electrodes. Namely, anodes containing tin, silicon, and graphite show a very good performance because of the large gravimetric and volumetric capacity of silicon and structural support provided...
Article
Full-text available
High-power high-density lithium rechargeable batteries are necessary to meet the energy demand of electric vehicles and high-power stationary grids. Here, we present a straightforward method for obtaining carbon nanofibers (CNFs) as a polysulfide barrier in Li-S cells, resulting in a significant increase in cell performance. CNFs were coated both o...
Article
Full-text available
We briefly summarize the most popular theoretical/computational techniques being used to model lithium-ion batteries and suggest some future tasks/challenges in the area.
Article
Full-text available
Nowadays, there is an evident need to improve the current Li‐ion battery systems, in order to make them more reliable, durable and safe. Regarding this objective, the application of composite materials –based mainly on the combination of Si, Sn and carbon– appears as a very promising alternative for future anode materials. However, despite the grea...
Article
In the present work we analyze the hot topic of integer and fractional stages lithium-ion batteries by Monte Carlo simulations. While fractional stages have been proposed through several experimental, simulations and theoretical measurements, in other experimental techniques, such as electrochemical ones, there is no evidence for them. In previous...
Article
The voltammetric behavior of Li+ intercalation/deintercalation in/from LiMn2O4 thin films and single particles is simulated, supporting very recent experimental results. Experiments and calculations both show that particle size and geometry are crucial for the electrochemical response. A remarkable outcome of this research is that higher potential...
Article
We perform ab initio calculations, within the density functional theory framework, of different lithium titanate compounds. In particular, Li4Ti5O12 (whose lithiated form is Li7Ti5O12) can be used as an anode in Li-ion batteries. Because of the complexity of the structures of these compounds, the related compounds LiTi2O4 and Li2Ti2O4 are analyzed...
Article
Lithium (Li) metal has been considered as an important anode candidate to reach more powerful energy storage devices with higher gravimetric and volumetric capacities. Nevertheless, the growth of high surface area lithium (HSAL) and dendrites during the stripping / deposition of Li causes safety concern and low cycle life of Li metal batteries. Her...
Article
Full-text available
The effect of temperature on the kinetics of electrochemical insertion/removal of lithium in graphite is analyzed by kinetic Monte Carlo methods. Different electrochemical techniques are simulated at different temperatures and responses are compared with experimental results. Simulated voltammograms show, similarly to experiment, how the behavior o...
Article
Full-text available
The effect of temperature on the kinetics of electrochemical insertion/removal of lithium in graphite is analyzed by kinetic Monte Carlo methods. Different electrochemical techniques are simulated at different temperatures and responses are compared with experimental results. Simulated voltammograms show, similarly to experiment, how the behavior o...
Article
To delve deeper into the kinetics involved in the staging phenomena of lithium insertion into graphite, it is necessary to develop theoretical models that emulate the physical phenomenon involved. In the present work kinetic Monte Carlo simulations are used to carry out a thorough analysis of the Li-ion graphite system, with the twofold aim of prov...
Article
Understanding the role of the phase transitions during lithiation and delithiation of graphite remains a problem of fundamental importance, but also practical relevance owing to its widespread use as the anode material in most commercial lithium-ion cells. Previously performed density functional theory (DFT) calculations show a rapid change in the...
Article
Full-text available
This study presents a simple and scalable synthesis of pyrite (FeS2) starting from S and Fe powders, which involves high-energy ball milling of precursor powders followed by a thermal treatment. The formation of the desired product was confirmed by X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, and X-ray photoelectron spectrosco...
Article
Many efforts in the area of renewable energies are focused in the development of batteries of electrochemical cells to store energy fulfilling the requirements of high energy and power density. Electrochemical cells based on Li-ions are able to satisfy the requirements of high energy and power density. In general, cell electrode materials based on...
Article
The interaction of polysulfides with graphene layers substitutionally modified with heteroatoms is analyzed using first-principles calculations, with the aim of using these structures to prevent polysulfide migration in lithium-sulfur batteries. The heteroatoms considered were B, N, O, F, Al, Si, P, S and Cl. An estimation of the residence time of...
Article
Full-text available
The electrochemical performance of SiO–SnCoC composite anode for high-energy lithium-ion batteries was evaluated with particular emphasis on the impact of Alginate as a polymeric binder, as well as fluoroethylene carbonate (FEC) as electrolyte additive. It was found that the presence of FEC and the use of alginate pH 3 as binder help to improve the...
Article
The growth of the corrosion layer occurring when a sodium surface is exposed to air under room conditions was studied considering the ratio between O − Kα and Na − Kα characteristic peak intensities from the X-ray emission spectrum collected in a scanning electron microscope for different exposure times of metallic sodium to air. Comparison between...
Article
Full-text available
Abstract An analytical model is proposed to investigate properties of composite electrodes that utilize more than one active material. We demonstrate how the equations can be applied to aid in the design of electrodes by comparing silicon-graphite and tin-graphite composite negative electrodes as examples with practical relevance. Based on simple a...
Article
Kinetic Monte Carlo simulations are applied to simulate the insertion of lithium ions into graphite. The present results show how the kinetics of lithium ion intercalation in graphite rules the global process, leading to metastable phases. The relatively slow rate of the events of insertion (deinsertion) of lithium ions into (from) graphite is foun...
Article
Full-text available
A computational model is proposed to study lithium-graphite intercalation compounds in the framework of Monte Carlo simulations in the Gran Canonical Ensemble. The results suggest the existence of fractional stages between stages II and I, which are rarely found in most experimental electrochemical measurements. These fractional stages seem to be p...
Article
Full-text available
The nucleation of Sn nanoparticles by chemical reduction was studied using three different carbonaceous substrates, to obtain Sn/C composites. When used as active materials in anodes for lithium-ion batteries, these composites displayed higher capacities than commercially used graphite, and showed a good cyclability. The differences in morphology,...
Article
New generations of materials are necessary to provide practical and economical solutions for electrode fabrication in lithium ion batteries. To this end, in the present work we propose a negative electrode based on a SiO2/C interconnected composite able to charge/discharge at high current regimes while maintaining a very good capacity. In order to...
Article
Full-text available
We have investigated the scenario for the hydrogen evolution reaction at stepped silver surfaces in acid solutions at high overpotentials using a simple kinetic model. Two independent types of sites, at the steps and at the terraces, were considered. The rate constants for the Volmer and Heyrovsky reactions were estimated. Both reactions occur with...
Article
Silica based materials are important candidates as anodes for lithium ion batteries due to their high specific capacity, low production and material cost and abundance in the earth crust. Silica lithiation leads to reversible and irreversible reactions to produce silicon, lithium oxide and lithium silicates. The final composition of these products...
Article
Underpotential deposition (upd) is a highly important topic within electrochemistry. Its discovery and early development are tightly connected with the rise of radiochemistry at the beginning of the last century and the nuclear weapon and atomic energy programs during and after World War II. Only later it reached fundamental electrochemistry in civ...
Article
In this work, a Monte Carlo study within the canonical assembly has been applied to elucidate the ion-lithium phase transition order of the Lithium-Graphite Intercalation Compound stage II (LiC12), around the critical point. The results reveal a weakly first order phase transition at 354.6±0.5 K with measures that follows power laws with effective...
Article
The coalescence process of two nanoparticles to yield a core-shell structure is analyzed by a Well-Tempered Metadynamics procedure. This methodology shows to be useful to understand the present phenomenon in terms of two collective variables: the distance between the center of mass of the coalescing particles and the gyration radius of the resultin...
Article
Li and C 1s core-electron excitation spectra of electrochemically prepared stage-II and stage-I lithiated graphite were investigated by means of inelastic X-ray scatteringspectroscopy. The near-edge structure is discussed, and the spectral features are interpreted using ab initio calculations. Our results confirm the invariance of the excitation th...
Article
An improved model to analyze the partial molar entropy step between stage II and stage I for lithium intercalation in graphite, based in statistical mechanics, is presented. At difference with our previous formulation, which assumed a priori heterogeneities, the present model considers the more realistic case of induced heterogeneities. The present...
Article
The relationship between the structure and crystallinity of lithium titanate Li4Ti5O12, at different synthesis post-treatment conditions on the electric energy storage capacity is discussed. Li4Ti5O12 was synthesized by solid-state reaction at a high temperature and time (950 °C, 24 h) and the resulting material was post-treated with a ball milling...
Article
Since their early times, by the 1950s, computational software and hardware have been growing in importance, to become today one of the key tools for the development and generation of knowledge. Increased computing power has radically transformed the way we make nowadays research. Today, it is possible to perform complex computational experiments wi...
Article
The deposition of particles in nanoholes is analyzed, taking into account the curvature of their inner walls. Different lattice-gas models of the nanoholes are considered. The heterogeneous surface are shaped from a (100)-surface where a nanohollow are incorporated with parallelepiped or polyhedral geometry. Several deposition stages are identified...
Chapter
In the following sections we will discuss on some tendencies and prospects concerning underpotential deposition (upd) research, related to both theoretical and experimental works.
Chapter
The underpotential deposition (upd) of metals may modify the catalytic activity of substrates in several ways. For the sake of simplicity, we divide the types of impacts that upd metals can produce in four types, although they all can in principle be acting on a given reaction at the same time.
Article
Full-text available
In order to examine the controversial hypothesis put forward to explain the entropy step experimentally observed for the stage II to stage I transition for lithium intercalation in graphite, a transparent statistical mechanical model is developed. The results obtained show that the entropy increase can be explained by the change of configurational...
Chapter
In this chapter, we give an overview of selected experimental and computer simulation literature research on thermodynamic modeling applied to the understanding of metal electrodeposition on metallic nanostructures. A brief survey on underpotential deposition, galvanic replacement, and dendrimer-encapsulated nanoparticles is given first. Focus is m...
Article
The addition of the reducing agent tris(2-carboxyethyl) phosphine (TCEP) during the formation of α,ω-alkanedithiols monolayers on Au(111) using the immersion method produces the assembly of monolayers with bicoordinated molecules (both S-terminal groups bound to the surface) that have a reductive desorption potential that is more positive than for...
Article
_Ab-initio_ DFT calculations are presented for the adsorption of phenacyl-1,2,3-benzotriazole on scheelite AMoO4 (A = Ca, Sr and Ba) surfaces. Strong adsorption energy of the organic ligand on the scheelite surface is found. The formation of a bond with covalent character is due to the interaction between the high electronic density of nitrogen and...
Article
Full-text available
In the present work, we study the adsorption of different monomolecular species on nanoparticles with different sizes and geometries using a grand canonical Monte Carlo method. These species are characterized by repulsive lateral interactions between themselves, as takes place in the case of the adsorption of partially charged atoms or molecules. N...
Book
With this volume, Ezequiel P. M. Leiva and co-authors fill a gap in the available literature, by providing a much-needed, comprehensive review of the relevant literature for electrochemists, materials scientists and energy researchers. For the first time, they present applications of underpotential deposition (UPD) on the nanoscale, such as nanopar...
Chapter
As can be found from the other chapters of this book, underpotential deposition shows a wide variety of behaviors, which involve the occurrence of several surface phases, formation of submonolayers, monolayers (ML) and eventually the formation of bilayers. Adsorption may be commensurate or incommensurate, where the ML may undergo compression, and m...
Chapter
The electrochemical deposition of metals on foreign substrates is a complex process which includes a number of phase formation phenomena. The very initial electrodeposition stages of a metal, M, on a foreign substrate, S, involve adsorption reactions as well as two- and/or three-dimensional nucleation and growth processes. The most important factor...
Chapter
As discussed in Chaps. 2 and 3, a wide variety of experimental techniques have allowed to obtain a wealth of information of upd systems. This information concerns:
Chapter
Macroscopic materials composed by transition metals such as Ag, Au, Cu, Pd, and Pt are ductile, malleable, display excellent electrical and heat conductivity and high optical reflectivity. These properties have allowed these materials to be widely used in several areas, such as electrical contacts and conductors and the catalysis of chemical reacti...
Book
With this volume, Ezequiel P. M. Leiva and co-authors fill a gap in the available literature, by providing a much-needed, comprehensive review of the relevant literature for electrochemists, materials scientists and energy researchers. For the first time, they present applications of underpotential deposition (UPD) on the nanoscale, such as nanopar...
Article
Nanowires of different metals undergoing elongation were studied by means of canonical Monte Carlo simulations and the embedded atom method representing the interatomic potentials. The presence of a surfactant medium was emulated by the introduction of an additional stabilization energy, represented by a parameter Q. Several values of the parameter...
Article
Full-text available
In this work the thermodynamics of the electrodeposition on nanoholes is analyzed. Different lattice-gas models of nanoholes, from parallelepiped geometry to the empty bulk of a nanoparticle, were considered. The models include curvature on the inner walls. Several stages of deposition are identified. Monte Carlo technique in the Grand Canonical En...
Article
Full-text available
Anions whose specific adsorption involves a proton-coupled electron transfer (PCET) include adsorbed OH (OHad), which plays an enormously relevant role in many fuel-cell reactions. OHad formation has often been found to happen in alkaline solutions at potentials more negative than expected from a Nerstian shift, and this has been proposed as the re...
Article
Full-text available
The main objective of this article is to analyze the feasibility of producing ammonia as main component for the synthesis of nitrogen fertilizers in the state of Ceará – Brazil. The potential for the ammonia production, via the Haber–Bosch process with electrolytic wind and solar photovoltaic hydrogen, is described with maps showing it per unit are...
Article
The wind map of the province of Córdoba, Argentina is improved starting from new wind measurements of ten meteorological stations installed in the province, whose equipment meets international standards for wind measurements. This correction is made on the basis of GIS Ordinary Cokriging interpolation method along with other wind global data basis....
Article
Using a combination of density functional theory and non-equilibrium Green function calculations, the effect of mechanically stretching a biphenyl-based molecular switch bonded to Au electrodes is studied. Thermodynamic and transport properties of the high and low conducting species are analyzed. A disulfide functionality bridging the aromatic ring...