The diversified essential properties of the stage-n graphite alkali-intercalation compounds are thoroughly explored by the first-principles calculations. According to their main features, the lithium and non-lithium materials might be quite different from each other in stacking configurations, the intercalated alkali-atom concentrations, the free conduction electron densities, and the atom-dominated & (carbon, alkali)-co-dominated energy bands. The close relations between the alkali-doped metallic behaviors and the geometric symmetries will be clarified through the interlayer atomic interactions, in which the significant alkali-carbon chemical bondings are fully examined from the atom- and orbital-decomposed van Hove singularities. The blue shift of the Fermi level, the n-type doping, is clearly identified from the low-energy features of the density of states. This study is able to provide the partial information about anode of Li+-based battery. There are certain important differences between AC$_6$/AC$_8$ and Li$_8$Si$_4$O$_{12}$.
Disordered rocksalt (DRX) Li3V2O5 is a promising candidate for anode in rechargeable lithium-ion batteries because of its ideal low voltage, high rate capability, and superior cycling stability. Herein, we presents a comprehensive study of intercalation chemistry of the DRX-Li3V2O5 anode using density functional theory calculations combined with machine learning cluster expansions and interatomic potentials. The predicted voltage profile of the disordered Li3V2O5 anode at room temperature based on Monte Carlo simulations with a fitted cluster expansion model is in excellent agreement with expe…
We report on the origin of the surface structural disordering in graphite anodes induced by lithium intercalation and deintercalation processes. Average Raman spectra of graphitic anodes reveal that cycling at potentials that correspond to low lithium concentrations in LixC (0 \leq x < 0.16) is responsible for most of the structural damage observed at the graphite surface. The extent of surface structural disorder in graphite is significantly reduced for the anodes that were cycled at potentials where stage-1 and stage-2 compounds (x > 0.33) are present. Electrochemical impedance spectra show …
We have investigated the possibility of using aluminum functionalized silicene trilayers (ABC-Si$_4$Al$_2$) as an anode material for alkali metal ion batteries (AMIBs). First, we studied the thermodynamic stability of ABC-Si$_4$Al$_2$ using ab-initio molecular dynamics simulations, showing that this material remains stable up to 600 K. Then, we explored the properties of alkali metal atoms (Li, Na, K) adsorption in ABC-Si$_4$Al$_2$, finding several available sites with high adsorption energies. Moreover, we computed the diffusion properties of those atoms along high-symmetry paths using the nu…
Layered platinum tellurium (PtTe2) was recently synthesized with controllable layer numbers down to a monolayer limit. Using ab initio calculations based on anisotropic Midgal-Eliashberg formalism, we show that by rubidium (Rb) intercalation, weak superconductivity in bilayer PtTe2 can be significantly boosted with superconducting Tc = 8 K in the presence of spin-orbit coupling (SOC). The intercalant on one hand mediates the interlayer coupling and serves as an electron donor, leading to large density of states at Fermi energy. On the other hand, it increases the mass-enhancement parameter wit…
The market quest for fast-charging, safe, long-lasting and performant batteries drives the exploration of new energy storage materials, but also promotes fundamental investigations of materials already widely used. Presently, revamped interest in anode materials is observed -- primarily graphite electrodes for lithium-ion batteries. Here, we focus on the upper limit of lithium intercalation in the morphologically quasi-ideal highly oriented pyrolytic graphite (HOPG), with a LiC$_6$ stoichiometry corresponding to 100\% state of charge (SOC). We prepared a sample by immersion in liquid lithium a…
Existence of van der Waals gaps renders two-dimensional (2D) materials ideal passages of lithium for being used as anode materials. However, the requirement of good conductivity significantly limits the choice of 2D candidates. So far only graphite is satisfying due to its relatively high conductivity. Recently, a new polymorph of layered germanium selenide (Gamma-GeSe) was proven to be semimetal in its bulk phase with a higher conductivity than graphite while its monolayer behaves semiconducting. In this work, by using first-principles calculations, we examined the possibility of using this n…
Boosting high-current alkaline water electrolysis and carbon dioxide reduction with novel CuNiFe-based anodes
University College London（伦敦大学学院）；University of Cambridge（剑桥大学）；Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC（意大利材料研究所（IOM）-国家研究委员会，TASC实验室）；Université Claude Bernard Lyon 1, CNRS, IRCELYON（里昂第一大学，法国国家科学研究中心，IRCELYON）；Iritaly Trading Company S.R.l.（Iritaly贸易公司）
Beyond Lithium-Ion Batteries: Are Effective Electrodes Possible for Alkaline and Other Alkali Elements? Exploring Ion Intercalation in Surface-Modified Few-Layer Graphene and Examining Layer Quantity and Stages
The interaction of metals with carbon materials, specifically with graphene, is of importance for various technological applications. In particular, intercalation of alkali metals is believed to provide a means for tuning the electronic properties of graphene for device applications. While the macroscopic effects of such intercalation events can readily be studied, following the related processes at an atomic scale in detail and under well-defined experimental conditions constitutes a challenge. Here, we investigate in situ the adsorption and nucleation of the alkali metals K, Cs, and Li on fr…
Finding electrode materials with high capacity is a key challenge for developing Lithium-ion batteries (LIBs). Graphene was once expected to be a promising candidate, but it turns out to be too inert to interact with Li. Here, by using the first-principles calculations, we predict that Germanium doped graphene, termed as Germagraphene which has been achieved in recent experiment, is a promising LIB anode material. We find that at the optimal Ge concentration, which corresponds to the chemical formula C17Ge, the specific capacity for Germagraphene can be as high as 1734 mAh/g, over four times l…
The cointercalation of sodium with the solvent organic molecule into graphite can resolve difficulty of forming the stage-I Na-graphite intercalation compound, which is a predominant anode of Na-ion battery. To clarify the mechanism of such cointercalation, we investigate the atomistic structure, energetics, electrochemical properties, ion and electron conductance, and charge transferring upon de/intercalation of the solvated Na-diglyme ion into graphite with {\it ab initio} calculations. It is found that the Na(digl)$_2$C$_n$ compound has the negatively lowest intercalation energy at $n\appro…
Co-intercalation is a potential approach to influence the voltage and mobility with which cations insert in electrodes for energy storage devices. Combining a robust thermodynamic model with first-principles calculations, we present a detailed investigation revealing the important role of H$_2$O during ion intercalation in nano-materials. We examine the scenario of Mg$^{2+}$ and H$_2$O co-intercalation in nano-crystalline Xerogel-V$_2$O$_5$, a potential cathode material to achieve energy density greater than Li-ion batteries. Water co-intercalation in cathode materials could broadly impact an …
Lithium-graphite intercalation compounds (Li-GICs) are the most common anode material for modern Li-ion batteries. However, the dielectric response of this material in the electrostatic limit (and its variation with the state of charge (SOC)) has not been investigated to a satisfactory degree, especially not for the higher SOC range. Nevertheless, said dielectric behaviour is a highly desired property, particularly as an input parameter for charged kinetic Monte Carlo simulations, one of the most promising modeling techniques for energy materials. In this work, we employ our recent DFTB parame…
The work functions (WF) of single-walled carbon nanotubes and bundles are studied using first principles methods. For individual metallic tubes, the WF is independent of the chirality and increase slightly with tube diameter. For semiconducting tubes, the WF (as defined by the HOMO energy) decreases rapidly. The WF of nanotube bundles ($\sim$ 5 eV) shows no clear dependence on the tube size and chirality, slightly higher than individual tubes. Calculations on finite tubes show no substantial difference in the tube end and the side wall. Upon alkali-metal intercalation, the WF decreases dramati…
Mg batteries utilizing a Mg metal anode with a high-voltage intercalation cathode define a potential pathway toward energy storage with high energy density. However, the realization of Mg batteries is plagued by the instability of existing electrolytes against the Mg-metal anode and high-voltage cathode materials. One viable solution to this problem is the identification of protective coating materials that could effectively separate the distinct chemistries of the metal-anode and the cathode materials from the electrolyte. Using first-principles calculations we map the electrochemical stabili…
Cycle life is critically important in applications of rechargeable batteries, but lifetime prediction is mostly based on empirical trends, rather than mathematical models. In practical lithium-ion batteries, capacity fade occurs over thousands of cycles, limited by slow electrochemical processes, such as the formation of a solid-electrolyte interphase (SEI) in the negative electrode, which compete with reversible lithium intercalation. Focusing on SEI growth as the canonical degradation mechanism, we show that a simple single-particle model can accurately explain experimentally observed capaci…
Properties of many layered materials, including copper- and iron-based superconductors, topological insulators, graphite and epitaxial graphene can be manipulated by inclusion of different atomic and molecular species between the layers via a process known as intercalation. For example, intercalation in graphite can lead to superconductivity and is crucial in the working cycle of modern batteries and supercapacitors. Intercalation involves complex diffusion processes along and across the layers, but the microscopic mechanisms and dynamics of these processes are not well understood. Here we rep…
Rational design of novel two-dimensional (2D) electrode materials with high capacity is crucial for the further development of Li-ion and Na-ion batteries. Herein, based on first-principles calculations, we systemically investigate Li and Na storage behaviors in the recently discovered 2D topological nodal-loop metal - the honeycomb borophene oxide (h-B2O). We show that h-B2O is an almost ideal anode material. It has good conductivity before and after Li/Na adsorption, fast ion diffusion with diffusion barrier less than 0.5 eV, low open-circuit voltage (less than 1 V), and small lattice change…
Recently "carbon ene-yne" (CEY), a novel full carbon two-dimensional (2D) material was successfully synthesized by the solvent-phase reaction. Motivated by this experimental effort, we conducted extensive first-principles density functional theory simulations to explore the application prospects of CEY as an anode material for Mg, Na and Li-ion batteries. To simulate the ionic intercalation process in an anode electrode, the adatoms coverage was gradually increased. We then employed Bader charge analysis to evaluate the charge transfer between the adatoms and the CEY nanosheet and finally to r…
Theoretical Studies on Sodium Storage Mechanism in Hard Carbon Anodes of Sodium-Ion Batteries: Molecular Simulations Based on Machine Learning Force Fields
The intercalation of alkali ions into layered materials has played an essential role in battery technology since the development of the first lithium-ion electrodes. Coulomb repulsion between the intercalants leads to ordering of the intercalant sublattice, which hinders ionic diffusion and impacts battery performance. While conventional diffraction can identify the long-range order that can occur at discrete intercalant concentrations during the charging cycle, it cannot determine short-range order at other concentrations that also disrupt ionic mobility. In this article, we show that the use…
Molecular-scale manipulation of electronic/ionic charge accumulation in materials is a preeminent challenge, particularly in electrochemical energy storage. Layered van der Waals (vdW) crystals exemplify a diverse family of materials that permit ions to reversibly associate with a host atomic lattice by intercalation into interlamellar gaps. Motivated principally by the search for high-capacity battery anodes, ion intercalation in composite materials is a subject of intense study. Yet the precise role and ability of heterolayers to modify intercalation reactions remains elusive. Previous studi…
In the present study we investigate the irradiation-defects hybridized graphene scaffold as one potential building material for the anode of Li-ion batteries. Designating the Wigner V22 defect as a representative, we illustrate the interplay of Li atoms with the irradiation-defects in graphene scaffolds. We examine the adsorption energetics and diffusion kinetics of Li in the vicinity of a Wigner V22 defect using density functional theory calculations. The equilibrium Li adsorption sites at the defect are identified and shown to be energetically preferable to the adsorption sites on pristine (…
Phosphorus has received recent attention in the context of high-capacity and high-rate anodes for lithium and sodium-ion batteries. Here, we present a first principles structure prediction study combined with NMR calculations which gives us insights into its lithiation/sodiation process. We report a variety of new phases phases found by AIRSS and the atomic species swapping methods. Of particular interest, a stable Na$_5$P$_4$-C2/m structure and locally stable structures found less than 10 meV/f.u. from the convex hull, such as Li$_4$P$_3$-P2$_1$2$_1$2$_1$, NaP$_5$-Pnma and Na$_4$P$_3$-Cmcm. T…
Graphite intercalation compounds (GICs) have a variety of functions due to their rich material variations, and thus,innovative methods for their synthesis are desired for practical applications. We have discovered that Na has a catalytic property that dramatically accelerates the formation of GICs. We demonstrate that LiC6n (n = 1, 2), KC8, KC12n (n = 2, 3, 4), and NaCx are synthesized simply by mixing alkali metals and graphite powder with Na at room temperature (~25 °C), and AEC6 (AE = Ca, Sr, Ba) are synthesized by heating Na-added reagents at 250 °C only for a few hours. The NaCx, formed b…
The prospects of phosphorene as an anode material for high performance Li-ion battery was systematically investigated from the first principle calculations and experimental measurements. The diffusion energy barriers of a Li atom moving along various orientations on phosphorene layer were calculated from the Li adsorption energy landscape. It was found that the diffusion mobility of a Li atom along the zigzag direction in the valley of phosphorene could be about 7 to 11 orders of magnitude faster than that along the other directions, indicating its ultrafast and anisotropic diffusivity. The li…
The abundance of Sodium (Na), its low-cost, and low reduction potential provide a lucrative inexpensive, safe, and environmentally benign alternative to Lithium Ion Batteries (LIBs). The significant challenges in advancing Sodium Ion Battery (NIB) technologies lies in finding the better electrode materials. Experimental investigations revealed the real potency of Germanium (Ge) as suitable anode materials for NIBs. However, a systematic atomistic study is necessary to understand the fundamental aspects of capacity-voltage correlation, microstructural changes of Ge, as well as diffusion kinetic…
Up to now, many guest atoms/molecules/ions have been successfully synthesized into graphite to form the various compounds. For example, alkali-atom graphite intercalation compounds are verified to reveal the stage-n structures, including LiC6n and LiM8n [M=K. Rb and Cs; n=1, 2, 3; 4]. On the other side, AlCl4-ion/molecule ones are examined to show stage-4 and stage-3 cases at room and lower temperatures, respectively. Stage-1 and stage-2 configurations, with the higher intercalant concentrations, are unable to synthesize in experimental laboratories. This might arise from the fact that it is q…
Black phosphorous is a layered material having a high capacity of 2596 mAh/g as a battery electrode, however it suffers from cracking due to high volume expansion during lithiation. These cracks causes loss of electrical contact in the whole material, therefore capacity fades after further cycles of charging and discharging. One needs a support material which would not crack with lithiation of phosphorous in order to keep the electrical contact of the material. Here, we considered phosphorene sandwiched between graphene layers. By using density functional theory, we calculated voltages of lith…
Study of In-plane and Interlayer Interactions During Aluminum Fluoride Intercalation in Graphite: Implications for the Development of Rechargeable Batteries
Using density functional theory calculations, we have investigated the structural, energetic, and electronic properties of ternary graphite intercalation compounds (GICs) containing alkali atoms (AM) and normal alkylamine molecules (nC$x$), denoted as AM-nC$x$-GICs (AM=Li, Na, K, $x$=1, 2, 3, 4). The orthorhombic unit cells have been used to build the models for crystalline stage-I AM-nC$x$-GICs. By performing the variable cell relaxations and the analysis of results, we have found that with the increase in the atomic number of alkali atoms the layer separations decreases in contrast to AM-GIC…
First-principles calculations of the electronic structure and vibrational modes, in a system of graphene bilayers and trilayers intercalated with alkaline earth atoms, are resented. It is found that, in similarity to the case of superconducting graphite intercalation compounds, the Fermi level is crossed by an s-band derived from the intercalant states, as well as graphitic pi-bands. The electron-phonon coupling parameter is found to be 0.60 and 0.80, respectively, in calcium intercalated graphene bilayers and trilayers. In superconducting CaC6 graphite intercalation compound, the calculated v…
A crucial ingredient in lithium (Li) and sodium (Na)-ion batteries (LIBs and NIBs) is the electrolytes. The use of Li-metal (Na-metal) as anode in liquid electrolyte LIBs (NIBs) is constrained by several issues including thermal runway and flammability, electrolyte leakage, and limited chemical stability. Considerable effort has been devoted toward the development of solid electrolytes (SEs) and all-solid-state batteries, which are presumed to mitigate some of the issues of Li-metal(Na-metal) in contact with flammable liquid electrolytes. However, most SEs, such as Li$_3$PS$_4$, Li$_6$PS$_5$Cl…
Iron and cobalt distannides \ce{MSn2} (M = Fe, Co) are regarded as a promising conversion-type anode material for lithium- and sodium-ion batteries, but their properties are not well understood. In this work, we report a first-principles study of alkali metal (A = Li, Na) substitutional effect on the structural, mechanical, lattice vibrational, electronic and defect properties of these distannides. Special attention is paid to systematic comparison between \ce{FeSn2} and \ce{CoSn2}. Our calculations reveal that M/A substitution induces a lattice expansion and decrease of elastic constants, whi…
MXenes' tunable properties make them excellent candidates for many applications in future nanoelectronics. In this work, we explore the suitability of Sc$_2$CX (X=N$_2$, ON, O$_2$) MXenes to act as the active anode materials in Na-ion based batteries (NIBs) by means of \textsl{ab initio} simulations. After analyzing the structural and elastic properties of all the possible models to evaluate the energetically favorable N and O functionalization sites, our calculations show that both Sc$_2$CON and Sc$_2$CN$_2$ present a clear metallic character, making them potential candidates as anode materia…
Rate-Dependent Reversibility and Lithium Losses in Hybrid Anode-Collector Metal Electrodes
Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid（马德里自治大学凝聚态物理系）；Instituto Universitario de Ciencia de Materiales Nicolás Cabrera (INC), Universidad Autónoma de Madrid（马德里自治大学尼古拉斯·卡布雷拉材料科学大学研究所）；Centro de Micro-Análisis de Materiales (CMAM), Universidad Autónoma de Madrid（马德里自治大学材料微分析中心）；Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid（马德里自治大学凝聚态物理中心）
Nanoscale imaging reveals critical plating and stripping mechanisms in anode-free lithium and sodium solid-state batteries
Autonomous University of Madrid (UAM)（马德里自治大学）；Nicolás Cabrera University Institute of Materials Science (INC), UAM（尼古拉斯·卡布雷拉大学材料科学研究院（INC））；ALBA Synchrotron Light Facility（阿尔巴同步辐射光源设施）；Norwegian University of Science and Technology (NTNU)（挪威科技大学）；Fraunhofer Institute for Ceramic Technologies and Systems (IKTS)（弗劳恩霍夫陶瓷技术和系统研究所）；Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas (CSIC)（马德里材料科学研究所，西班牙国家研究委员会）；National Institute of Advanced Industrial Science and Technology (AIST), Research Institute for Energy Efficient Technologies（国立先进工业科学技术研究院，能源效率技术研究所）；Condensed Matter Physics Center (IFIMAC), UAM（凝聚态物理中心（IFIMAC））
We present a comparative ab initio study of Li, Na, and Mg storage in tin, including phononic effects and phase competition between alpha and beta Sn. Mg doping at low concentration is found to stabilize the beta phase. On the contrary, Li and Na doping is shown to reverse the stability of the phases at room temperature: Li/Na-doped alpha-Sn is more stable than Li/Na-doped beta-Sn up to a temperature of around 380/400 K. This may rationalize the formation of alpha-Sn upon lithiation and delithiation of beta-Sn anodes reported in experimental studies. The changes in phase stability with Li/Na/M…
Reductive hydrogenation was applied to two types of single-walled carbon nanotubes with different diameter range. Alkali metal intercalation, followed by reaction with methanol, led to hydrogenated products. Both yield and selectivity of this reaction showed strong dependence on diameter, contrary to expectation based on simple curvature effects. The observed yield, as detected by thermogravimetry-mass spectroscopy and 1H-NMR, is drastically reduced in small-diameter tubes where the alkali dopant does not reach the inside of the bundles. Wide range optical transmission measurements were employ…
