Lithium Atoms Research Articles

Application of the Jost Function for Calculation of the Ground State of the Lithium Atom

Application of the Jost Function for Calculation of the Ground State of the Lithium Atom

A Constrained CASSCF(2,2) Approach to Study Electron Transfer between a Molecule and Metal Cluster.

We have implemented a constrained CASSCF(2,2) calculation so as to study thermal electron transfer between a chlorine ion and a cluster of lithium atoms of variable size (from 1 to 17). Our calculations illustrate how the geometry of the ground state-charge transfer state crossing point (as well as the strength of a diabatic coupling) can depend sensitively on the number of metal ions (i.e., the size of the cluster) and the relative positioning of the donor and acceptor. Thus, this set of calculations is an initial step toward understanding the transition from homogeneous to heterogeneous electron transfer. In the future, these constrained calculations should allow us to model still far larger systems, ideally opening up a pathway to study meaningful electrochemical phenomena.

Electrical conduction and optical characteristics of Li2O and Bi2O3 Co-doped zinc-phosphate glassy nanocomposites: A critical observation of mixed ionic electronic effect

In the present report, the combined effects of the co-doping of metal oxide (Bi2O3) and Lithium oxide (Li2O) into the glassy matrix with chemical composition xLi2O-(0.45-x)Bi2O3-(0.15ZnO-0.40P2O5) (x = 0.05, 0.15, 025, and 0.35 mol%) are investigated thoroughly. The FESEM and X-ray diffraction data affirm the crystalline nature of the studied glassy composites. The obtained band gap energy values are declined from (3.68–3.17) eV, while the Urbach energy values are declined from (0.38–0.27) eV. Moreover, the mechanism responsible for AC conductivity has been analyzed using Almond–West formalism and Jonscher's universal power law. The observed rise in both AC and DC conductivity in the glass samples is attributed to the mixed ionic electronic effect. In the ionic diffusion model, an increased defect site concentration improves Li+ ion migration through percolation channels. The reduction in both electrostatic binding energy and strain energy lowers the Anderson-Stuart activation energy, facilitating Li+ ion migration and enhancing conductivity. Additionally, in the small polaron hopping model, an increase in the density of defect states suggests more defect sites that facilitate electronic hopping, creating deep localized states and transitions between localized and extended states. Replacing a Bismuth atom with a Lithium atom increases the number of non-bridging oxygen, enhancing the conduction band tail, reducing the energy needed for hopping conductivity, and increasing conductivity.

Laser-Induced Solid-Phase Strategy to Synthesize Single-Atomic Lithiophilic Sites Enabled Dendrite-Free Lithium Deposition on Graphene Matrix.

The introduction of metal Single-atom (SA) to construct lithium-philic active sites shows the ability to guide uniform lithium deposition and improve the stability of lithium hosts. Nevertheless, the development of facile and expedient methods for synthesizing SA remains a considerable challenge. Herein, The SA metal loaded on graphene (Bi@LrGO) is designed by laser-induced solid-phase strategy. The bismuth salts simultaneously decompose under the high local temperature and in the reductive atmosphere induced by laser to form SA metal. Simultaneously, graphene oxide (GO) nanosheets absorb photon energy to be reduced/graphitized into graphene, which serves as anchoring sites for Bismuth Sing-atom (Bi SA) immobilization. The SA metals, supported on the graphene not only provide sufficient lithiophilic sites but also significantly increase the adsorption energy (-2.11eV) with lithium atoms, promote the uniform nucleation and deposition of lithium, and inhibit the growth of lithium dendrites. Additionally, the layered structure of the graphene film adapts to the volume change during the repeated lithium plating/stripping process. Therefore, the symmetrical battery-based Li deposited on Bi@LrGO (Bi@LrGO@Li) achieves an ultra-long stable cycle life of ≈2400h at 1mAcm-2. In particular, a full cell with LiFePO4 cathode provides a good capacity retention of 81.2% at 4C after 600 cycles.

A theoretical exploration of monomer activation mechanisms in bis-lithium N[sbnd]heterocyclic carbenes complexes for enhanced understanding of charge distribution in ring-opening polymerization of ε-caprolactone

A comprehensive examination was conducted on the ring-opening polymerization (ROP) mechanism of ε-caprolactone (ε-CL) employing bis-lithium N-heterocyclic carbene complexes (bisLiNHCs) in a theoretical framework. The modeled reactions were carried out utilizing density functional theory at B3LYP level. An activated-monomer mechanism was observed, characterized by occurrence of two distinct transition states. Initiating with activation of ε-CL via two lithium atoms from bisLiNHCs catalysts, the ensuing step involved nucleophilic addition of carbonyl group stemming from the lithium benzoxide (LiBnO) initiator. The ring opening ε-CL was accomplished via classical cleavage of acyl-oxygen bond. The determination of reaction barrier heights for ε-caprolactone with bisLiNHCs catalysts involved the examination of potential energy profiles. The computed energy profiles revealed exothermic characteristics for each ROP reaction, with the identification of a rate-determining step occurring at the second transition state, which entailed cleavage of acyl-oxygen bond from monomer. Furthermore, through comparisons catalytic capabilities of bisLiNHCs derivatives and energy barrier heights, it was observed that the length and flexibility of linker chain as well as steric effects from substituent groups, significantly influenced the geometric configuration. These specific variations induce alterations in both distance and angular orientation, which are pivotal aspects influencing the chelation dynamics between lithium and oxygen atoms.

Nuclear-excited source of coherent and incoherent radiation with direct nuclear pumping

Uranium fission fragments, as well as the products of 3He(n,p)3H and 10B(n,α)7Li nuclear reactions were utilized in the nuclear reactor for gas ionization and excitation. However, the 6Li(n,α)3H nuclear reaction was less examined. The use of lithium-6 as a surface source of excitation of the gas medium, due to the long path length of tritium nuclei in the gas, allows to excite large volumes of gas as opposed to using 235U or 10B.While investigating the luminescence of noble gases in the core of the IVG.1M research reactor, we noted an appearance of alkali metal lines and a sharp increase in the intensity of these lines at temperatures above 570 K. It was determined that the population of levels of lithium atoms has practically no effect on the population of the 2p-levels of atoms of noble gases. The selectivity of p- and s-levels deactivation by lithium atoms implies the possibility of creating inversion of population at 2p-1s transitions of noble gas atoms. Successful experiments to study the luminescence of gases upon excitation by 6Li(n,α)3H nuclear reaction products allow us to proceed to experiments to achieve the laser action threshold and study the lasing characteristics of gas mixtures at the IGR pulsed nuclear reactor with thermal neutron flux density up to 7∙1016 n/cm2s. For this purpose, an experimental device designs were proposed to perform experiments on the IGR reactor. A step-by-step procedure of fabrication of a nuclear-excited source for excitation of gas mixtures is provided. The results of reactor experiments aimed at determining the spectral and temporal characteristics of optical radiation during excitation of gas mixtures by 6Li(n,α)3H nuclear reaction products are presented.

TPDH-Graphene as a New Anodic Material for Lithium Ion Battery: DFT-Based Investigations.

The potential of tetra-penta-deca-hexagonal graphene (TPDH-gr), a recently proposed 2D carbon allotrope as an anodic material in lithium ion batteries (LIBs), was investigated through density functional theory calculations. The results indicate that Li-atom adsorption is moderate (around 0.70 eV), allowing for easy desorption. Moreover, energy barriers (0.08-0.20 eV), diffusion coefficient (>6 × 10-6 cm2/s), and open circuit voltage (0.29 V) calculations show rapid Li atom diffusion on the TPDH-gr surface, stable intercalation of lithium atoms, and good performance during the charge and discharge cycles of the LIB. These findings, combined with the intrinsic metallic nature of TPDH-gr, indicate that this new 2D carbon allotrope is a promising candidate for use as an anodic LIB material.

Theoretical design of graphene/tungsten dichalcogenide (Gr/WX2, X=S, Se) heterostructures used for anode materials of LIBs from DFT calculations

2D van der Waals heterostructures are highly promising for Lithium-ion batteries (LIBs), offering excellent energy capacity and extended lifespan when used as anodes. In this study, we systematically investigate the geometrical structures and electronic properties of graphene/tungsten dichalcogenide (Gr/WX2, X=S, Se) heterostructures, focusing on lithium (Li) atom adsorption and movement in these materials using first-principles calculations through density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. Our results reveal that the Gr/WX2 heterostructures possess excellent structural stability, with mechanical strength validated by their elastic constants. The diffusion barriers of Li atoms in Gr/WS2 and Gr/WSe2 heterostructures are competitive compared with other anode materials. Additionally, the Li diffusion coefficients at 300 K for Gr/WS2 and Gr/WSe2 are also surpassing those observed in pristine Gr. Furthermore, Gr effectively lowers the average open-circuit voltage (OCV) of Gr/WX2 heterostructures to optimal levels, with Gr/WS2 at 0.29V and Gr/WSe2 at 0.25V. The Gr/WS2 and Gr/WSe2 heterostructures after adsorption of Li exhibit remarkable thermal stability at 300K, maintaining their structural integrity throughout the simulation period. Our research provides comprehensive theoretical guidance for the practical development and application of Gr/WX2 heterostructures as anode materials in LIBs.

Fusing together an outline design for sustained fuelling and tritium self-sufficiency.

Ensuring tritium fuel self-sufficiency while maintaining continuous and high-specification fuel flow to the tokamak via a low tritium inventory and controllable fuel cycle is a significant challenge to the STEP plant design. Effective and high-quality fuelling and exhaust design is required to sustain and control a stable plasma, whereas fuel sufficiency is required to prevent depletion of available tritium supply. Concerns regarding the lack of tritium availability preventing continuous tritium import are countered by breeding, where highly energetic neutrons from the core fusion reactions interact with lithium atoms suspended in the surrounding breeder blanket to produce tritium. The compact nature of STEP prohibits the integration of inboard breeder blankets posing a significant challenge for the design team looking to ensure more tritium is bred and made available than consumed within the core plasma. This paper outlines how purposeful technology selection and system architecting has converged on the outline of a conceivable and tritium-capable fuel cycle and breeder blanket design. Before introducing the STEP fuel cycle design outline and summarizing the approach undertaken to address the challenges facing plasma fuelling, key aspects of fuel self-sufficiency are discussed. This includes discussing a proposed helium-cooled liquid lithium breeder blanket and possible technology options for tritium extraction from lithium. Lastly, there is a brief process modelling overview, which emphasizes the central contribution of various employed modelling methods. Reflections on the presented fuel cycle design outline conclude that substantial development work is still required to realize a continuous tritium fuel cycle design and overcome the major challenges posed by tritium and lithium handling. Reflections on the presented breeder blanket design proposal conclude that while many substantial risks and blockers remain to achieve fuel self-sufficiency, high breeding ratios are expected to be achievable with a compact spherical tokamak configuration. Nonetheless, it is recognized that further consideration is required to ensure that the selection of liquid lithium as a breeder medium provides the overall simplest route to a self-sufficient and realizable design.This article is part of the theme issue 'Delivering Fusion Energy - The Spherical Tokamak for Energy Production (STEP)'.

Atomistic insights into role of urea additive in lithium nanoparticles formation

Recently, urea additive has been demonstrated to benefit the formation of cathode nanomaterials through spray flame synthesis with improved homogeneity in lithium atoms distribution. Nevertheless, its intrinsic mechanism has not been well understood. In this study, reactive molecular dynamic simulations are performed to gain atomistic insights into the pyrolysis and oxidation mechanisms of a lithium precursor droplet with or without urea additive. A series of comparisons involving the reaction kinetics and pathways of lithium clusters, along with the gas release, energy profiles and morphological characteristics of droplets, is conducted to elucidate the role of urea additive at 1500 K and 0.1 MPa. Urea additive is observed to exert a homogenising impact on the distribution of lithium atoms within the synthesized nanoparticles, as evidenced by the decreased number of large-sized lithium agglomerates and less concentrated lithium element. This can be ascribed to changed reaction pathways of lithium clusters due to urea additive, where the lithium clusters are prone to decompose into fine nanoparticles through initial bonding with urea atoms, followed by bond-breaking to generate gases. The increased amount of gas released from the decomposition of precursor with urea additive leads to a more violent droplet microexplosion, which in turn results in droplet breakup and thus fine droplets. As the ambient temperature is elevated, the presence of urea additive facilitates the formation of fine-sized nanoparticles with enhanced homogeneity of lithium atoms.

Theoretical Study on the Dynamics of Lithium-Ion Transport in PPS-Based Polymer Electrolytes

The development of solid-state lithium-ion batteries (LIBs) is a key advancement in energy storage technology. Solid electrolytes are important in this development because they are safer and more stable than liquid electrolytes, and they have higher energy density. Among the various types of solid electrolytes, Polyphenylene Sulfide (PPS)-based solid-state polymer electrolytes (SPEs) are notable for their ability to conduct ions as well as liquid electrolytes across a wide range of temperatures. This ability is particularly important because other solid polymer electrolytes, like those based on polyethylene oxide (PEO), struggle with ion conduction at different temperatures. PPS-based SPEs are different because their ion transport does not depend on the movement of the polymer chains, which means their ion conduction remains steady from high to low temperatures.The previous study conducted a series of first-principle calculations, revealing that the introduction of neutral molecules, referred to as agent molecules, can significantly enhance the movement of lithium ions within a solid matrix when these are mixed with lithium salts. This is because the intermolecular interactions within a binary system comprising an agent molecule and lithium salt are governed by a strong bond formation between lithium and oxygen atoms. When these agent molecules are introduced, they replace the anionic species around lithium in the salts, leading to a weakened Coulomb force between lithium and oxygen. This reduction is essential for rapid lithium-ion movement through the easy separation of lithium salts and the subsequent generation of ion-hopping sites characterized as lithium-free oxygen cages. According to the previous study, the strategic selection of neutral molecules with functional groups that bolster chemical resonance is imperative. Such molecules have been identified as promising candidates for agent molecules.Our study builds upon previous research by directly incorporating PPS polymers into our computational simulations. We utilized molecular dynamics and quantum mechanics to examine the role of neutral molecules in PPS in facilitating lithium-ion mobility. We parameterized our system with quantum mechanics calculations, which were crucial in informing our molecular dynamics simulations. Using VASP program for interaction assessment and LAMMPS program for energy and structure analysis, we refined our models to understand the interactions between PPS polymers, Li+ ions, TFSI- ions, and Chloranil molecules. Our simulations explored the structural dynamics and the effects of fillers and PPS polymer layers on ion transport.Our work enhances the basic understanding of SPEs and helps in the creation of new lithium-ion batteries that perform better and are safer. We've pinpointed important factors that control how lithium ions move in PPS-based electrolytes, laying the groundwork for future improvements in solid-state electrolytes and leading to lithium-ion batteries that are more effective and safer.Reference:[1] Jiwon Yu, Myungsuk Lee, Yeonseo Kim, Hyung-Kyu Lim, Jonghyun Chae, Gyeong S. Hwang, Sangheon Lee, “Agent molecule modulated low-temperature activation of solid-state lithium-ion transport for polymer electrolytes”, Journal of Power Sources 505, 229917 (2021).

Scalable and Non-Destructive Analysis of Battery Degradation and Performance

Electrochemical processes occurring during battery operation are highly complex. Thermodynamic, kinetic and transport-based phenomena all play a significant role in the dynamic evolution of the time-based electrochemical response of any battery system. Researchers have long sought to quantify these various interconnected phenomena, but to-date elucidating the role these mechanisms play in the performance of battery systems has been challenging or impossible. To aid researchers in uncovering the mechanistic behavior of their systems, we have developed a novel testing protocol and corresponding data analysis method that is scalable and non-destructive (SAND). This protocol and analysis can be applied to any battery system, in any form factor, at any point in the battery life cycle; including R&D, manufacturing, and second life battery screening to name a few.The testing protocol is based on a series of galvanostatic current pulses at a variety of currents and/or times. By utilizing the natural differences in time-constant of the various electrochemical phenomena inside a battery, this technique can probe each mechanism to glean novel insight using standard battery cycling equipment. Specifically, the insights this technique can provide include: the electrochemical potential of each phase during lithiation and delithiation quantification of electrode kinetics at various states-of-charge (including exchange current density estimation from the Butler-Volmer model)quantitative estimation of transport-based polarization losses from both the electrodes and the electrolyte. This analysis provides an un-parallelled level of mechanistic insight into the inner workings of any battery, at any point, spanning small-scale R&D cells to large format cells in mass production.To demonstrate the capabilities of this technique this presentation will focus on the analysis of multiple cells (same model) from a Tier 1 supplier containing a lithium transition metal oxide cathode material cycled at various temperatures. These results have led to an extensive set of conclusions. For brevity a few of these conclusions are: The initial exchange current density of these cells is calculated to be 25.5 A/m2. The H2→H3 phase transition during charging is the least efficient phase, exhibiting the largest power loss during chargingThe inefficiencies in the H2→H3 phase transition are dominated by solid-state lithium atom diffusion within the electrodes. At low current densities the overpotential associated with transport is the dominant source of losses, while at higher currents kinetic overpotentials become the dominant source. In summary, we have developed a novel characterization technique requiring only standard battery cycling equipment that can be easily and quickly performed by researchers around the world. Whether on small-scale coin cells or large-format pouch cells, the analysis from this technique will give the battery community insight into the thermodynamic, kinetic, and transport properties of their system. Moreover, this technique can be applied in a variety of contexts related to battery development, including understanding degradation mechanisms, performing root-cause analysis of manufacturing defects, or providing more accurate parameters for computational modeling.

Ab Initio Tomography Analysis of Lithium Incorporation and Diffusion in Multidomain Silicon Suboxide Anode Materials

Silicon is considered a promising anode material to supplant conventional graphite materials in lithium-ion batteries due to its higher theoretical energy-storage capacity compared to graphite. However, the widespread application of Si anodes has been hindered because the capacity of Si anodes decreases rapidly as the charge/discharge cycle proceeds. The controlled incorporation of oxygen into Si is often considered as a feasible approach for employing Si as an anode material in the form of silicon suboxide. Silicon suboxide exhibits a lower energy capacity compared to pure Si, but offers enhanced stability against volume expansion. Consequently, silicon suboxide materials have been commercialized by blending them with graphite. However, the blending ratio of silicon suboxide with graphite is limited to low levels due to its poor first-cycle efficiency, so-called initial Coulombic efficiency. In-depth understanding of the lithium interaction characteristics within multidomain silicon suboxide is indispensable for optimizing the electrochemical performance of silicon suboxide anode materials for lithium-ion batteries. In this study, we investigate the domain-dependent thermodynamic and kinetic properties of lithium atoms within systematically designed multidomain silicon suboxide models composed of Si, SiO2, and Si/SiO2 interface by performing a series of computational simulations combined with a unique tomography-like sampling scheme. We find that the Si/SiO2 interfacial region exhibits preferential thermodynamics and kinetics for lithiation and can serve as a critical lithium transport channel during charge-discharge cycles, while the SiO2 domain is likely to be excluded from lithiation due to its high resistance to lithium diffusion. Consequently, a significant fraction of lithium is expected to be trapped at the Si/SiO2 interface during the discharge process, which ultimately contributes to a low initial Coulombic efficiency. This theoretical understanding suggests that the formation of continuously connected lithium-transportable Si/SiO2 interfacial channels surrounding the Si domains, along with a well-structured shallow SiO2 framework through the use of appropriate synthesis methods, is essential for maximizing the electrochemical performance of silicon suboxide anode materials. Our theoretical approach offers new insights into the atomistic characteristics of silicon suboxide during lithiation/delithiation processes, ultimately enabling the identification of the origin of low ICE and strategies for addressing it.References(1) Chae, S.; Lim, H.-K.; Lee, S. Energy Landscapes for Lithium Incorporation and Diffusion in Multidomain Silicon Suboxide Anode Materials. ACS Applied Materials & Interfaces 2023, 15 (49), 57059-57069. DOI: 10.1021/acsami.3c12846. Figure 1

Adsorption and diffusion behavior of lithium atom on boron-doped armchair graphene nanoribbon- A dispersion-corrected DFT study

In this paper, we study the relevance of considering dispersion interactions in DFT calculations to determine the adsorption behavior of lithium atom(s) on boron-doped armchair graphene nanoribbons. Our findings suggest that substitutional doping with boron atoms makes the AGNR electron-deficient which results in charge transfer from Li to the AGNR. Li atom binds more strongly to B-doped AGNR than pristine AGNR. A stronger Li-C interaction prevents the clustering of Li atoms, thus, inhibiting dendrite growth. The maximum storage capacity of B-doped AGNR reaches to 1261 mAh/g. B-doped AGNR offers a lower diffusion barrier of 0.19 eV to Li atom as compared to pristine AGNR. From the analysis of density of states, it is observed that the semiconducting nature of both pristine and B-doped AGNRs turns into metallic after the adsorption of lithium atom. Our results show that B-doped AGNR can be used as a potential anode material of lithium-ion batteries.

Asymmetrical TiSSe Monolayers as Catalytic Materials for Lithium-Sulfur Batteries: A DFT Study

Asymmetrical Janus TiSSe monolayers as cathode materials for lithium-sulfur batteries were studied by first-principles calculations, encompassing adsorption, catalytic, and conductive properties. The polarization effect, arising from the asymmetric arrangement of constituent elements, results in variability in adsorption energy and bonding processes across S/Se surfaces. The moderate adsorption energy of Lithium Polysulfides (LiPSs) on the TiSSe monolayer effectively mitigates the shuttle effect. The bond formation process investigated by charge transfer, physical/chemical adsorption, and projected crystal orbital Hamiltonian population (pCOHP), revealed its emergence in the early lithiation stage. The Gibbs free energies for the reduction reaction of sulfur on the S/Se surface demonstrate a significant enhancement in the transformation kinetics. The low decomposition and diffusion energy barriers for lithium atoms on the S/Se surface of the TiSSe monolayer indicate its catalytic potential in facilitating sulfur redox transformation. The TiSSe monolayer exhibits metallic properties before and after polysulfide absorption, thereby enhancing electron transport capacity in Li-S batteries. Therefore, the Janus TiSSe monolayer presents a new perspective for the selection of battery adsorption materials in lithium-sulfur batteries.

Measurement of the three-body-recombination coefficient of ultracold lithium and strontium atoms

Measurement of the three-body-recombination coefficient of ultracold lithium and strontium atoms

Synthesis and Characterization of Alkali Metal Hypersilyl Borates

AbstractThis study focuses on the synthesis of H‐ and MeO‐ functionalized alkali metal hypersilyl borates. Consequently, two distinct silanides were used as polysilane frameworks for our chemical manipulations. Tris(silyl)silanide (1) and tris(trimethoxysilyl)silanide (2) react in the same manner with the BH3 ⋅ SMe2 complex to obtain two new alkali metal hypersilyl borates [(R3Si)3SiBH3M (M=alkali metal; R=H, (3), R=MeO, (4 a–c))] in good to excellent yields. NMR spectroscopy for all compounds and single‐crystal X‐ray crystallography for 3 and 4 a, b enabled a clear structural characterization. Single crystal X‐ray analysis of 3 showed a dimeric structure, where two THF‐molecules and three hydrides from the BH3‐group contribute to the coordination sphere of the lithium atom. Interestingly, crystals suitable for X‐ray analysis of 4 a and 4 b showed a solvent‐free cluster formation, due to the coordination of the MeO groups. Both species form coordination polymers with different coordination modes depending on the nature of the alkali metal. Attempted hydride abstraction reactions of 3 and 4 with various reagents under the formation of the free boranes proceeded unselectively.

Modeling of the Electronic Properties of M-Doped Supercells (М = Zr, Nb) with a Monoclinic Structure For Lithium-Ion Batteries

The T–x phase diagram of the quasi-binary system Li2O–TiO2 was refined and the isothermal cross section of the ternary Li–Ti–O system at 298 K was constructed. The equilibrium phase regions of Li–Ti–O in the solid state are determined with the participation of boundary binary oxides and four intermediate ternary compounds , , and . Using the density functional theory (DFT LSDA) method, the formation energies of the indicated ternary compounds of the Li2O–TiO2 system were calculated and the dependence of on the composition was plotted. Ab initio modeling of supercells based on M-doped anode material based on the (LTO) compound with a monoclinic structure () was carried out. It has been shown that partial substitution of cations and oxygen in the m-LTO–M structure increases the efficiency of a lithium-ion battery (LIB) both by stabilizing the structure and by increasing the diffusion rate of . Due to the contribution of d-orbitals (Zr4+-4d, Nb3+-4d orbitals) to the exchange energy, partial polarization of electronic states occurs and the electronic conductivity of m-LTO–M increases. The formation of oxygen vacancies in the m-LTO–M crystal lattice, as in binary oxides, can create donor levels and improve the transport of and electrons. M-doping of the m-LTO structure by replacing cations, in particular lithium, with Zr or Nb atoms noticeably reduces the band gap (Eg) of m-LTO–M supercells. In this case, in the m-LTO–M band structure, the Fermi level shifts to the conduction band and the band gap narrows. Decreasing the Eg value increases the electronic and lithium-ion conductivity of m-LTO–M supercells.

Coherent control of multiphoton ionization of lithium atoms by a bichromatic laser field

We demonstrate a left-right asymmetry control of the photoelectron angular distribution in multiphoton ionization of Li atoms by a bichromatic laser field. By delaying the fundamental (780 nm) and its second harmonic relative to each other in steps of 130 attoseconds, we can vary the relative phase between the two laser fields with subwavelength accuracy and thereby steer the ejected electrons. Good agreement is found between the measurements and calculations at the appropriate intensities of the two harmonics. Published by the American Physical Society 2024

Enhancement of electrochemical stability by molecular cation vacancies of the electrode material CH3NH3NiCl3 for lithium-ion batteries

At present, efforts are being made to find new low-cost materials for photovoltaic, optoelectronic and energy storage applications. In this regard, compounds of the halide perovskite type have been increasingly studied over the past few years. The incorporation of small cations in these compounds and their possible use in rechargeable batteries can be achieved by the electrochemical reversibility technique, where perovskites with large cations are used to obtain a new isostructural compound with smaller cations and large interstitial space or free vacancies for ionic transport. The present work studied the electrochemical reversibility of lithium-ion into CH3NH3NiCl3 (MANiCl3) active material, after the formation of MA+ vacancies or interstitial spaces, taking both experimental and theoretical approaches. The material displayed an anodic behavior and an initial capacity of discharge of ca. 170 mAhg−1 at 0.2C (0.1 mA), a full capacity retention up to the first 25 cycles of charge–discharge, and even reached a retention of up to 80 % of initial capacity at the 80th cycle. First-principles density functional theory calculations show that the shape of the crystal lattice and volume changes of all the different phases involved in the electrochemical process are tiny, at about 3 Å3 per cell. In addition, there are no appreciable elastic contributions to the energy variation during the de-lithiation/lithiation process, indicating that memory effects are not an issue. The calculated formation energies of the lithiated structures and the open circuit voltages are −2.91 eV and 1.33 V for LinMA1-nNiCl3 and −1.41 eV and 2.91 V for Li2nMA1-nNiCl3, respectively. These findings suggest that incorporating one or, at most, to two lithium atoms is favorable for the overall stability and electrochemical performance.