Li Atoms Research Articles

MoSe2 monolayer as a two-dimensional anode material for lithium-ion batteries: A first-principles study

Nowadays, finding applicable electrode materials with high energy density and high cycle stability is highly desired in the field of lithium-ion batteries. MoSe2 monolayer has been experimentally synthesized and shows satisfactory metal anchoring capability, making it a potential candidate for energy storage devices. In this work, first-principles calculations are employed to investigate the potential of MoSe2 monolayers with different phases (1T, 1T′ and 1H) as anode materials. The results show that 1T′-MoSe2 monolayer has excellent thermal, dynamical and mechanical stability. In addition, 1T′-MoSe2 monolayer exhibits metallic property under Li adsorption, ensuring good electrical conductivity for efficient electron transport. The Li atom has a low diffusion barrier of 0.299 eV on 1T′-MoSe2 monolayer, which results in a good charge-discharge rate. 1T′-MoSe2 monolayer has a maximum Li storage capacity of 422 mA h/g and an open-circuit voltage of 0.21 V. Our work reveals the application of 1T′-MoSe2 monolayer as an anode material for lithium-ion batteries and promotes the design of energy storage materials based on two-dimensional transition metal dichalcogenides.

Concise synthetic routes for diphenylacetylene from tetrachloroethylene using Suzuki coupling reaction followed by treatment with n-butyllithium

Abstract We wish to report a new synthetic approach for diphenylacetylene in which tetrachloroethylene was reacted with phenylboronic acid in the presence of Pd catalyst, followed by a workup procedure to provide the crude product, which was then allowed to react with n-butyllithium via the halogen lithium exchange of Cl atom and loss of Li and Cl atoms to afford the desired diphenylacetylene in good yield.

Machine learning accelerates design of bilayer-modified graphene hydrogen storage materials

To accelerate the exploration of modified graphene hydrogen storage materials, this paper proposes a Data-Driven Exploration Framework (DDEF) based on the best-fitting machine learning (ML) algorithms (Random Forest: Recall = 0.83, Accuracy = 0.83, Gradient boosted regression: R2 = 0.90, RMSE = 0.06) and density functional theory (DFT). The hydrogen storage capacity of bilayer double-deficient graphene (BDG[Li]) doped with B atoms and modified with Li and Ti atoms was predicted using ML, which shortens the design cycle of hydrogen storage materials. The interlayer composite hydrogen storage mechanism of the BDG[Li] structure is revealed by electronic property analysis. For the first time, the calculation method of the interlayer electrostatic force energy (Ej) is proposed, and the equation for calculating the interlayer H2 adsorption energy is optimized. The hydrogen storage data of BDG[Li] and the construction of Ej provide new feature data for subsequent ML calculations. Both DDEF and Ej are computationally verified to have high accuracy and generalizability, which is of research significance for accelerating the design of hydrogen storage materials.

Engineering catalytic defects via molecular imprinting for high energy Li-S pouch cells

ABSTRACT Heterogeneous catalysis promises to accelerate sulfur-involved conversion reactions in lithium-sulfur batteries. Solid-state Li2S dissociation remains as the rate-limiting step because of the weakly matched solid-solid electrocatalysis interfaces. We propose an electrochemically molecular-imprinting strategy to have a metal sulfide (MS) catalyst with imprinted defects in positions from which the pre-implanted Li2S has been electrochemically removed. Such tailor-made defects enable the catalyst to bind exclusively to Li atoms in Li2S reactant and elongate the Li–S bond, thus decreasing the reaction energy barrier during charging. The imprinted Ni3S2 catalyst shows the best activity due to the highest defect concentration among the MS catalysts examined. The Li2S oxidation potential is substantially reduced to 2.34 V from 2.96 V for the counterpart free of imprinted vacancies, and an Ah-level pouch cell is realized with excellent cycling performance. With a lean electrolyte/sulfur ratio of 1.80 μL mgS–1, the cell achieves a benchmarkedly high energy density beyond 500 Wh kg–1.

Applicability of the Zintl Concept to Understanding the Crystal Chemistry of Lithium-Rich Germanides and Stannides.

With this contribution, we take a new, critical look at the structures of the binary phases Li5Ge2 and Li5Sn2. Both are isostructural (centrosymmetric space group R3̅m, no. 166), and in their structures, all germanium (tin) atoms are dimerized. Application of the valence rules will require the allocation of six additional valence electrons per [Ge2] or [Sn2] unit considering single covalent bonds, akin to those in the dihalogen molecules. Alternatively, four additional valence electrons per [Ge2] or [Sn2] anion will be needed if homoatomic double bonds exist, in an analogy with dioxygen. Therefore, five lithium atoms in one formula unit cannot provide the exact number of electrons, leaving open questions as to what is the nature of the chemical bonding within these moieties. Additionally, by means of single-crystal X-ray diffraction, synchrotron powder X-ray diffraction, and neutron powder diffraction, we established that the Li and Sn atoms in Li5Sn2 are partially disordered, i.e., the actual chemical formula of this compound is Li5-xSn2+x (0 < x < 0.1). The convoluted atomic bonding in the case where tin atoms partially displace lithium atoms results in the formation of larger covalently bonded fragments. Our first-principle calculations suggest that such disorder leads to electron doping. Contrary to that, both experimental and computational findings indicate that in the Li5Ge2 structure, the [Ge2] dimers are slightly oxidized, i.e., hole-doped, as a result of approximately 30% vacancies on a Li site, i.e., the actual chemical formula of this compound is Li5-xGe2 (x ≈ 0.3).

Effect of biaxial tensile-compressive deformation on the optoelectronic properties of monolayers of MoTe2 with adsorbed alkali metals X (X = Li, Na, K, Rb, Cs): a first principles

Based on a first-principles approach, the effects of tensile-compression deformation on the structural stability, electronic structure, and optical properties of monolayers of MoTe2 adsorbed with alkali metal atoms X (X = Li, Na, K, Rb or Cs) were calculated. It was found that the structural stability of the MoTe2 monolayer after adsorption of Li atoms was the most stable, with the smallest adsorption and formation energies and the smallest adsorption height. The movement of the Fermi energy toward the conduction band makes the system an n-type semiconductor. Subsequently, the adsorbed Li-MoTe2 monolayers were selected for tensile-compressive deformation, and with the increase of tensile deformation, the band gap decreased to zero at 10% deformation and exhibited metallic properties. As compressive deformation grows, the band gap shifts from direct to indirect, and metallic characteristics emerge when deformation approaches −10%. The Te-s and Te-p orbital electrons near the Fermi energy level and Mo-d orbitals make the main contribution to the adsorbed alkali metal molybdenum ditelluride system. In terms of optical characteristics, the MoTe2 system after alkali metal adsorption deformation is blue-shifted/ red-shifted at the absorption/reflection peak. These discoveries may help to broaden the possible applications of MoTe2 in low-dimensional electron-emitting devices.

Computational Investigation of a Reversible Energy Storage Medium in g-B5N3 Decorated by Lithium.

Graphene-like materials in two dimensions hold great promise for energy storage and transformation applications owing to their distinctive features, such as lightweight composition, porous geometry, etc. Among these materials, a recently discovered unit known as g-B5N3 has demonstrated high performance in energy storage and transformation. In our efforts to enhance its applicability in adsorbing energy gases, we propose a novel composite structure by decorating Li atoms on the surface of pristine g-B5N3. The electronic properties of this composite have been comprehensively investigated using a first-principles method. Our findings reveal that the added Li atoms can be securely anchored on the g-B5N3 with an adsorption energy of -3.01 eV. Furthermore, the Li atom transfers its partial 2s electrons to the g-B5N3, exhibiting considerable electropositivity. These metallic sites effectively polarize the adsorbed H2 molecules, enhancing the mutual electrostatic interactions. Each primitive cell of Li-doped g-B5N3 can adsorb up to 13 H2 molecules, resulting in a storage capacity up to 6.3 wt %. This capacity significantly surpasses the goal of 4.5 wt % set by the U.S. Department of Energy. Furthermore, the typical adsorption energy of -0.209 eV per molecule of H2 aligns with the energy range suitable for reversible hydrogen storage. This study underscores the potential of Li-doped g-B5N3 for energy gas adsorption, shedding light on further advancements in this field.

Investigation of cathode properties of two-dimensional NbS2Cl2 for Li and Na-ion batteries using density functional theory

Exploring novel two-dimensional materials (2D) for electrode and electrochemical storage applications stands as a pivotal pursuit in advancing renewable energy technologies. While recent research has predominantly focused on anode materials, cathode materials have received comparatively lesser attention. This study delves into the potential cathode applications of the novel two-dimensional material NbS2Cl2 using density functional theory. Fundamental properties, encompassing electronic and thermodynamic attributes, were scrutinized to comprehend the material’s characteristics. Our investigation extended to examining the adsorption and diffusion properties of these electrode materials. Comprehensive calculations of mechanical and thermodynamic properties reaffirmed the stability of this system. Upon adsorption of Li/Na atoms, the conducting nature emerged, evident through charge density difference and projected density of states. Our findings notably reveal minimal diffusion barriers of 1.5 eV and 0.35 eV for Li and Na atoms. Moreover, the observed open circuit voltages for adsorbed Li and Na ions were 4.69 V and 2.62 V, respectively. The calculated theoretical capacity for adsorbed Li-ion on 2D-NbS2Cl2 is 400 mAh g−1, while for Na-ion adsorption, it is 353 mAh g−1, awaiting validation through future experimental verifications.

New Diabatic Potential Energy Surfaces for the Li + H2 Reaction and Time-Dependent Quantum Wave Packet Studies.

New global diabatic potential energy surfaces (DPESs) for the ground (12A') and first excited (22A') states for the Li + H2 system were developed, with more than 30,000 energy points at the IC-MRCI+Q level of theory, utilizing the aug-cc-pV5Z basis set for the H atoms and the cc-pCV5Z basis set for the Li atom, fitted by a single neural network (NN) with symmetry. Product state-resolved quantum dynamics calculations of the nonadiabatic reaction Li (2P) + H2 (X 1 ∑g+, v0 = 0, j0 = 0) → LiH (X 1∑+) + H(2S) were carried out using these new DPESs and also the previous HYLC-DPESs. The numerical results suggested that our newly constructed DPESs provided an accurate description of the LiH2 system.

Construction and catalysis role of a kinetic promoter based on lithium-insertion technology and proton exchange strategy for lithium-sulfur batteries

The high theoretical energy density and specific capacity of lithium-sulfur (Li-S) batteries have garnered considerable attention in the prospective market. However, ongoing research on Li-S batteries appears to have encountered a bottleneck, with unresolved key technical challenges such as the significant shuttle effect and sluggish reaction kinetics. This investigation explores the catalytic efficacy of three catalysts for Li-S batteries and elucidates the correlation between their structure and catalytic impacts. The results suggest that the combined utilization of lithium-insertion technology and a proton exchange approach for δ-MnO2 can optimize its electronic structure, resulting in an optimal catalyst (H/Li inserted δ-MnO2, denoted as HLM) for the sulfur reduction reaction. The replacement of Mn sites in δ-MnO2 with Li atoms can enhance the structural stability of the catalyst, while the introduction of H atoms between transition metal layers contributes to the satisfactory catalytic performance of HLM. Theoretical calculations demonstrate that the bond length of Li2S4 adsorbed by the HLM molecule is elongated, thereby facilitating the dissociation process of Li2S4 and enhancing the reaction kinetics in Li-S batteries. Consequently, the Li-S battery utilizing HLM as a catalyst achieves a high areal specific capacity of 4.2 mAh cm−2 with a sulfur loading of 4.1 mg cm−2 and a low electrolyte/sulfur (E/S) ratio of 8 μL mg−1. This study introduces a methodology for designing effective catalysts that could significantly advance practical developments in Li-S battery technology.

Investigation of N C and B C bilayers as anode materials for Li-ion batteries by first-principles calculations.

The best choice today for a realistic method of increasing the energy density of a metal-ion battery is to find novel, effective electrode materials. In this paper, we present a theoretical investigation of the properties of hitherto unreported two-dimensional B C and N C bilayer systems as potential anode materials for lithium-ion batteries. The simulation results show that N C bilayer is not suitable for anode material due to its thermal instability. On the other hand B C is stable, has good electrical conductivity, and is intrinsically metallic before and after lithium intercalation. The low diffusion barrier (0.27 eV) of Li atoms shows a good charge and discharge rate for B C bilayer. Moreover, the high theoretical specific capacity (579.57 mAh/g) connected with moderate volume expansion effect during charge/discharge processes indicates that B C is a promising anode material for Li-ion batteries.

Li-decorated C48B12 and Li12C48B12-impregnated MOF-5 for hydrogen storage: A multi-scale simulation study

In this study, we employed density functional theory (DFT) to investigate the adsorption sites and quantities of Li atoms on the C48B12 surface. Additionally, we examined the hydrogen adsorption properties of the formed Li12C48B12 through ab initio molecular dynamics (AIMD) simulations. Our AIMD simulations confirmed the stability of adsorbed Li atoms on the C48B12 surface, computed adsorbed H2 quantities, and predicted gravimetric densities of H2 adsorption on Li12C48B12 at 77 K and 298 K. Grand Canonical Monte Carlo simulations explored the H2 gravimetric densities of pure MOF-5, C48B12-impregnated MOF-5, and Li12C48B12-impregnated MOF-5 at 77 K and 298 K within 100 bar. Li doping on the C48B12 surface did not significantly enhance the gravimetric densities of H2 in MOF-5 but enhanced the stability of H2 adsorption in MOF-5.

Point Defects in Hexagonal SiP Monolayer: A Systematic Investigation on the Electronic and Magnetic Properties

AbstractIn this work, point defects are proposed to modify the electronic and magnetic properties of SiP monolayer. Pristine monolayer is a non‐magnetic semiconductor 2D material with energy gap of 1.52(2.21) eV as predicted by PBE(HSE06) functional. Single Si vacancy (), Si+P divacancy (), and substituting one P atom by one Si atom () magnetize significantly SiP monolayer. Herein, total magnetic moments between 1.00 and 2.00 are obtained . In contrast, no magnetism is induced by single P vacancy (), substituting one Si atom by one P atom (), and exchanging pair Si‐P positions (). Moreover, significant magnetization of SiP monolayer is also achieved by doping with single Li and Cu atoms ( and ), as well as pair of Li and Cu atoms ( and ). Total magnetic moments between 0.84 and 1.42 are obtained. Interestingly, the half‐metallicity is observed in and systems. When substituting P atom, F, Cl, and Br impurities reduce significantly the SiP monolayer bandgap, preserving its non‐magnetic nature. In contrast, a total magnetic moment of 1.26 is obtained by doping with I atom. Results presented herein may introduce the defected and doped SiP systems as prospective 2D candidates for spintronic and optoelectronic applications.

Enhanced Piezocatalytic Performance of Li-doped BaTiO3 Through a Facile Sonication-Assisted Precipitation Approach.

Piezocatalysis-induced dye degradation has garnered significant attention as an effective method for addressing wastewater treatment challenges. In our study, we employed a room-temperature sonochemical method to synthesize piezoelectric barium titanate nanoparticles (BaTiO3: BTO) with varying levels of Li doping. This approach not only streamlined the sample preparation process but also significantly reduced the overall time required for synthesis, making it a highly efficient and practical method. One of the key findings was the exceptional performance of the Li-doped BTO nanoparticles. With 20 mg of Li additive, we achieved 90 % removal of Rhodamine B (RhB) dye within a relatively short timeframe of 150 minutes, all while subjecting the sample to ultrasonic vibration. This rapid and efficient dye degradation was further evidenced by the calculated kinetic rate constant, which indicated seven times faster degradation rate compared to pure BTO. The enhanced piezoelectric performance observed in the Li-doped BTO nanoparticles can be attributed to the strategic substitution of Li atoms, which facilitated a more efficient transfer of charge charges at the interface. Overall, our study underscores the potential of piezocatalysis coupled with advanced materials like Li-doped BTO nanoparticles as a viable and promising solution for wastewater treatment, offering both efficiency and environmental sustainability.

Enhanced hydrogen storage of single-layer blue phosphorus by synergistic effect between doped lightweight elements and grafted lithium atoms

Single-layer blue phosphorus (SLBP) has displayed charming photoelectric performances, but its property in hydrogen storage is not outstanding due to the weak interactions. To expand the application of SLBP in hydrogen storage, we attempt to screen SLBP-based materials with stable structures and strong polarity using density functional theory by doping lightweight elements and grafting alkali metal atoms. The simulation results indicate that the lightweight elements (B, C, N, O and F) doped SLBP systems have more stable structures due to the strong orbital interaction than pure SLBP, and exhibit electron deficient characteristics. Compared to the pure SLBP, the H2 adsorption energies of the doped systems improve and range from 0.05 to 0.09 eV, but it still cannot meet the requirements of ideal hydrogen storage. Therefore, the lightweight element doped SLBP systems are further grafted by Li atom. Under the synergistic effect of doping lightweight elements and grafting Li atoms, H2 molecules are strongly polarized, and the corresponding adsorption energies of H2 reach to 0.16, 0.26, 0.28, 0.30, and 0.10 eV, respectively. It is worth emphasizing in the C-doped SLBP system that the hydrogen storage capacity of reaches 5.53 wt% for each Li atom adsorbs one hydrogen molecule and the corresponding adsorption energy is 0.23 eV/H2 when the ratio of C to P atoms increases to 6:26. For each Li atom adsorbs two hydrogen molecules in the same hydrogen storage system, the hydrogen storage capacity reaches 10.48 wt% with 0.18 eV/H2 adsorption energy. We hope these results can provide theoretical basis and scientific guidance for searching for SLBP-based materials with excellent hydrogen storage performances at ambient temperature.

Mitigated reaction kinetics between lithium metal anodes and electrolytes by alloying lithium metal with low-content magnesium

Lithium (Li) metal is regarded as a promising anode candidate for high-energy-density rechargeable batteries. Nevertheless, Li metal is highly reactive against electrolytes, leading to rapid decay of active Li metal reservoir. Here, alloying Li metal with low-content magnesium (Mg) is proposed to mitigate the reaction kinetics between Li metal anodes and electrolytes. Mg atoms enter the lattice of Li atoms, forming solid solution due to the low amount (5 wt%) of Mg. Mg atoms mainly concentrate near the surface of Mg-alloyed Li metal anodes. The reactivity of Mg-alloyed Li metal is mitigated kinetically, which results from the electron transfer from Li to Mg atoms due to the electronegativity difference. Based on quantitative experimental analysis, the consumption rate of active Li and electrolytes is decreased by using Mg-alloyed Li metal anodes, which increases the cycle life of Li metal batteries under demanding conditions. Further, a pouch cell (1.25 Ah) with Mg-alloyed Li metal anodes delivers an energy density of 340 Wh kg−1 and a cycle life of 100 cycles. This work inspires the strategy of modifying Li metal anodes to kinetically mitigate the side reactions with electrolytes.

Layered Hydride LiH4 with a Pressure-Insensitive Superconductivity.

For hydride superconductors, each significant advance is built upon the discovery of novel H-based structural units, which in turn push the understanding of the superconducting mechanism to new heights. Based on first-principles calculations, we propose a metastable LiH4 with a wavy H layer composed of the edge-sharing pea-like H18 rings at high pressures. Unexpectedly, it exhibits pressure-insensitive superconductivity manifested by an extremely small pressure coefficient (dTc/dP) of 0.04 K/GPa. This feature is attributed to the slightly weakened electron-phonon coupling with pressure, caused by the reduced charge transfer from Li atoms to wavy H layers, significantly suppressing the substantial increase in the contribution of phonons to Tc. Its superconductivity originates from the strong coupling between the H 1s electrons and the high-frequency phonons associated with the H layer. Our study extends the list of H-based structural units and enhances the in-depth understanding of pressure-related superconductivity.

PHOTH-graphene: a new 2D carbon allotrope with low barriers for Li-ion mobility

The continued interest in 2D carbon allotropes stems from their unique structural and electronic characteristics, which are crucial for diverse applications. This work theoretically introduces PHOTH-Graphene (PHOTH-G), a novel 2D planar carbon allotrope formed by 4-5-6-7-8 carbon rings. PHOTH-G emerges as a narrow band gap semiconducting material with low formation energy, demonstrating good stability under thermal and mechanical conditions. This material has slight mechanical anisotropy with Young modulus and Poisson ratios varying between 7.08-167.8 GPa and 0.21-0.96. PHOTH-G presents optical activity restricted to the visible range. Li atoms adsorbed on its surface have a migration barrier averaging 0.38 eV.

Theoretical study of hydrogen storage in Li-decorated Al12N12 clusters

The hydrogen storage capacity of Li-decorated Al12N12 clusters is investigated using density functional theory computations. The present results indicate that Li atoms are strongly attached on tops of N atoms of the Al12N12 nanocage, forming Al12N12Lim (m = 1, 2, 4, 8, 12) complexes. The binding energies of the Li atoms on the Al12N12 are in the range of 1.60–1.95 eV, which are larger than that among Li atoms. The clustering of Li atoms can be effectively prevented on the surface of the host. The charge transfer from Li atoms to the Al12N12 makes Li atoms positively charged. Each Li atom in the Li-decorated Al12N12 complexes can adsorb a maximum of 3 H2 molecules with the average adsorption energy of 0.09–0.12 eV/H2. The polarization interaction is responsible for the adsorption of H2 molecules to Li-decorated Al12N12 complexes. The fully coated Al12N12Li12 complex can hold up to 36 H2 molecules, and the corresponding gravimetric density of hydrogen is 11.2 wt%, far exceeding the ultimate target of 6.5 wt% of U. S. DOE.

Metallic Be[formula omitted]M (M = Al, Ga) monolayers as potential universal anodes for Li and post-Li ion batteries

Developing excellent comprehensive performance anode materials is of vital importance for rechargeable metal ion batteries in the domain of energy conversion and storage. By first-principles calculations, we have appreciated that the highly conductive planar hexacoordinate Be2Al and Be2Ga monolayers can be served as universal anodes for alkali/alkaline metal ion batteries. Due to favorable adsorption energy landscape, the diffusion barriers of Li, Na, K, and Ca atoms on the Be2Al and Be2Ga surfaces are as low as 0.116, 0.075, 0.046, 0.270 eV and 0.044, 0.025, 0.014, 0.217 eV, respectively, indicative of fast rate capabilities. At the same time, the Be2Al and Be2Ga monolayers exhibit the desirable mean open-circuit voltages of 0.049 and 0.104 V for Li+, 0.234 and 0.278 V for Na+, 0.249 and 0.227 V for K+, as well as 0.120 and 0.124 V for Ca2＋, respectively, conducive to achieve high operating voltage at the full-cell level. Arising from stable double-sided multilayer adsorption, the Be2Al (Be2Ga) monolayer can deliver ultrahigh reversible specific capacities up to 2382 (1222), 4764 (1833), 2382 (1222), and 7146 (3665) mA h g−1 for Li, Na, K, and Ca atoms, respectively. All of these advantages along with reliable cycling stability demonstrate that these two 2D materials enjoy great potential as promising anodes for Li, Na, K, and Ca ions batteries.