High Li-ion Storage Research Articles

In situ construction of a continuous ionic conductive coating for a high-performance Li3VO4 anode

An organic interface nanolayer is effectively coated on the LVO nanoparticle surface by an in situ solid–liquid chemical reaction for high Li-ion storage performance.

Atomistic-Scale Simulations Toward the Understanding of the Conversion–Alloying Mechanism in Li-Ion Battery Anodes

The increasing demands for energy storage call for improved capacity and cycling stability of modern Li-ion batteries (LIBs). However, the application of the state-of-the-art LIB anode material – graphite is limited as graphite underperforms as a high-rate/high-storage-capacity anode. Alternatively, materials capable of alloying with Li-ions have attracted attention as a promising pathway to solve high-rate and high-capacity challenges. Furthermore, when alloying reaction in a material is coupled with irreversible conversion reaction, the materials operating under such mechanism exhibit a high Li-ion storage capacity and long-term stability during electrochemical cycling. However, despite the optimistic performance of these materials, a number of parameters need to be optimized and fundamentally understood.Among the unknowns for the conversion/alloying materials are the atomistic details of the reaction mechanism - understanding the atomistic structure during transformations is a pre-requisite for the future rational optimization of the materials. Furthermore, amorphization, which is prevalent in these materials, severely limits the conventional characterization methods essentially impeding further development and understanding the degradation mechanisms. Hence, to investigate the atomistic structure changes, we proposed a computational methodology for these conversion-alloying materials and their reaction mechanism by taking amorphous substoichiometric silicon nitride as a showcase system [1]. The molecular dynamics (MD) simulations utilized the ReaxFF parameter set which was specifically developed for the investigation. Subsequently, the experimental pair distribution functions (PDF) were used to verify the modeling results.While the reactive molecular dynamics was coupled with the PDF simulation to complement the experimental measurements, the effective and practical approach guided us to the atomistic structure evolution understanding for LIBs in a conversion–alloying process, revealing the bond coordinations around the Si atoms in the active material. Consequently, the analysis opened an in-depth understanding of the cycling stability of substoichiometric a-SiNx anode materials by revealing the atomistic features relevant to the changes this material undergoes during lithiation and delithiation processes in a LIB. Furthermore, the proposed approach allows modeling of the changes at the atomistic scale for the amorphous materials and predicting the experimental PDF at different cycling stages, verifying the modeling outcome. The topic also addresses the applications of the approach for other anode materials.

Multifunctional 0D@2D (Mox-Mn)Sy-NPs@MXene hybrid electrode with high rate-capability and ultra-long cycling life for Li-ion battery and all Molybdenum-MXene-based 1.9 (V) asymmetric supercapacitor

0D@2D heterostructures constituted by binary transition metal sulfides@transition metal carbides can illustrate the combined advantages of each material with their improved electrochemical performance for energy storage devices. 2D transition metal carbides (MXene ∼ Ti3C2) have presented themselves as the most appropriate candidates for the construction of lower-dimensional 0D ∼ like electroactive nanoparticles (NPs). Due to the high theoretical capacity values and versatile valence states, the molybdenum incorporated mixed metal sulfides ((Mox-Mn)Sy) nanoparticles decorated over 2D Ti3C2 sheets are reported for Li-ion battery and asymmetric supercapacitor. A uniquely designed (Mox-Mn)Sy-NPs@MXene hybrid material displays a high Li-ion storage capacity of up to 698 mA h g−1 at 50 mA g−1, and a commendable areal capacity performance (∼1.27 mA h cm−2 at 2 mA cm−2) for supercapacitor, along with outstanding capacity retention at higher current density and stable cycling performance. Furthermore, a 0D@2D (Mo-Fe7)Sx-NPs@MXene hybrid material is utilized as anode material to construct a coin cell-like (Mox-Mn)Sy-NPs@MXene//(Mo-Fe7)Sx-NPs@MXene asymmetric supercapacitor (ASC) device. A high-voltage (∼1.90 V) ASC device based on unique 0D@2D heterostructures displays an ultra-high energy density of 78.8 W h Kg−1 at a power density of 634.63 W Kg−1 along with maximum specific capacity retention and cycling stability performance. This study emphasizes the importance of 0D@2D based heterostructure materials for the development of efficient energy storage devices.

Magnetite nanoparticles embedded on reduced graphene oxide as an anode material for high capacity and long cycle-life Li-ion battery

A facile and cost-effective method was developed for the synthesis of “magnetite/reduced graphene oxide” nanocomposite, as an anode material for lithium-ion batteries. The fabricated composite was characterized by different instrumental analyses including XRD, Raman, XPS, SEM, TEM, and FTIR, as well as various electrochemical (i.e. battery) tests. Such broad examination revealed the structure of the prepared material and its electrochemical behavior. It was found that the fabricated composite has a number of advantages over the currently utilized electrode materials such as cost efficiency, high Li ion storage (2528 mAh/g at 0.05 A/g at 1st discharge), cycle stability of 986 mAh/g over 100 cycles at a current density of 0.1 A/g, and eventually Coulombic efficiency of about 100 %. In comparison, the reduced graphene oxide (rGO) shows inferior performances, such as a constant capacity of 462 mAh/g, and a slower kinetics of the ion storage. Consequently, the synthesized low-cost anode material seems to be an attractive candidate for development of the next-generation energy-storage devices, used in electrical vehicles, and portable electronic instruments.

Molybdenum Atom Engineered Vanadium Disulfide for Boosted High-Capacity Li-Ion Storage.

A drawback with lithium-ion batteries (LIBs) lies in the unstable lithium storage which results in poor electrochemical performance. Therefore, it's of importance to improve the electrochemical functionality and Li-ion transport kinetics of electrode materials for high-performance lithium storage. Here, a subtle atom engineering via injecting molybdenum (Mo) atoms into vanadium disulfide (VS2 ) to boost high capacity Li-ion storage is reported. By combining operando, ex situ monitoring and theoretical simulation, it is confirmed that the 5.0%Mo atoms impart flower-like VS2 with expanded interplanar spacing, lowered Li-ion diffusion energy barrier, and increased Li-ion adsorption property, together with enhanced e- conductivity, to boost Li-ion migration. A "speculatively" optimized 5.0% Mo-VS2 cathode that exhibits a specific capacity of 260.8mA h g-1 at 1.0 A g-1 together with a low decay of 0.009% per cycle over 500 cycles is demonstrated. It is shown that this value is ≈1.5 times compared with that for bare VS2 cathode. This investigation has substantiated the Mo atom doping can effectively guide the Li-ion storage and open new frontiers for exploiting high-performance transition metal dichalcogenides for LIBs.

Li/Na/K-ion reaction pathways in Ga and high-performance amorphous Ga composite anodes for Li-ion batteries

To achieve high-performance Ga anodes for alkali-ion batteries, the electrochemical Li/Na/K-ion reaction pathways in Ga are thoroughly elucidated using ex situ analytical tools. Ga exhibits a high Li-ion storage reaction owing to the formation of Li2Ga (theoretical capacity: 769 mAh g−1). However, it exhibits poor Na- and K-ion storage reactions owing to the formation of NaGa4 (theoretical capacity: 96 mAh g−1) and K3Ga13 (theoretical capacity: 89 mAh g−1), respectively. The high Li-ion storage reaction in Ga demonstrates its potential as an anode for Li-ion batteries (LIBs). Therefore, we fabricate an amorphous Ga composite (Ga/C) comprising amorphous Ga homogeneously distributed in an amorphous carbon using a simple one-pot solid-state mechanical process. Ga/C exhibits high reversible capacity, long-term Li-ion storage stability, and high rate capability. In addition, three-step confinement of amorphous Ga in the composite during continuous cycling is demonstrated and suggested as an enhancement mechanism for high-performance Ga/C anodes for LIBs. The interesting Li-ion storage reaction in Ga and high-performance amorphous Ga composites are expected to be highly applicable to LIB anodes.

Post-synthetic Fully π-Conjugated Three-Dimensional Covalent Organic Frameworks for High-Performance Lithium Storage

A fully π-conjugated nitrogen-rich three-dimensional covalent organic framework (PYTRI-COF-2) containing both pyrazine and triazine units was prepared through a post-synthetic strategy. The imine linkages in the pre-prepared PYTRI-COF-1 were converted into heterocyclic quinoline by the Povarov reaction. The obtained PYTRI-COF-2 displayed high Li-ion storage capacity and excellent cycling stability when it was used as the lithium (Li)-ion battery electrode.

Sustainable development of manganese sulfoselenide nanoparticles anchored graphene oxide nanocomposite for high-performance supercapacitor and lithium-ion battery applications

Transition metal chalcogenides have been described as promising electrode materials for supercapacitors due to their low electronegativity, suitable electrical conductivity, comparatively higher specific capacitance, and favorable electrochemical redox regions. However, the poor electrical conductivity and substantial volume fluctuations provide a significant obstacle to industrial use. A new method to develop metal incorporated GO at the time of GO synthesis and subsequent conversion to metal sulfoselenides is proposed and demonstrated here. This novel process incorporates the advantages of both GO and the metal sulfoselenides for electrochemical energy storage applications. The average size of the nanoclusters was 52 nm as identified by Transmission electron microscopy. As pseudocapacitive electrode GO-MnSSe delivered a specific capacitance of 603 F/g at 0.1 A/g in 1 M KCl of aqueous electrolyte, because of their distinct and stable form. The fabricated 2-electrode device showed a specific capacitance of 98.5 mF/cm2 at 80 µA/cm2, showing good retention of 67 % at the end of the 9000 cycles. As Li-ion battery half-cells, at specific currents of 50, 100, 250, and 500 mA/g, GO-MnS delivered a capacity of 587, 378, 273, and 211 mA h/g respectively, reflecting a retention rate of 64 %, while the specific current was increased 10 times. The initial capacity of GO-MnS and GO-MnSSe at 100 mA/g was 494 and 495 mAh/g respectively, and for GO-MnS and GO-MnSSe at 250 mA/g the delivered capacity values were 376 and 363 mA h/g respectively. Coulombic efficiency (CE) for GO, GO-SW (single wash), GO-MnS, and GO-MnSSe were 99.52 %, 99.6 %, 98.7 %, and 99 % respectively at the end of the 100 cycles. Moreover, GO-MnS were cycled at a higher rate of 500 mA/g for 500 cycles which showed a decay initially nevertheless it stabilized after few cycles and showed a retention of 88 % at the end of 500 cycles from 20th cycle. The ex-situ morphological analysis of GO-MnS were conducted as well as the kinetic of the electrode were studied by before and after cycling EIS measurement. As part of this, as an anode for lithium-ion batteries, high Li-ion storage capacity and cyclic stability were observed.

Two Birds with One Stone: Prelithiated Two-Dimensional Nanohybrids as High-Performance Anode Materials for Lithium-Ion Batteries.

As an inexpensive and naturally abundant two-dimensional (2D) material, molybdenum disulfide (MoS2) exhibits a high Li-ion storage capacity along with a low volume expansion upon lithiation, rendering it an alternative anode material for lithium-ion batteries (LIBs). However, the challenge of using MoS2-based anodes is their intrinsically low electrical conductivity and unsatisfied cycle stability. To address the above issues, we have exploited a wet chemical technique and integrated MoS2 with highly conductive titanium carbide (Ti3C2) MXene to form a 2D nanohybrid. The binary hybrids were then subjected to an n-butyllithium (n-Buli) treatment to induce both MoS2 deep phase transition and MXene surface functionality modulation simultaneously. We observed a substantial increase in 1T-phase MoS2 content and a clear suppression of -F-containing functional groups in MXene due to the prelithiation process enabled by the n-Buli treatment. Such an approach not only increases the overall network conductivity but also improves Li-ion diffusion kinetics. As a result, the MoS2/Ti3C2 composite with n-Buli treatment delivered a high Li-ion storage capacity (540 mA h g-1 at 100 mA g-1), outstanding cycle stability (up to 300 cycles), and excellent rate capability. This work provides an effective strategy for the structure-property engineering of 2D materials and sheds light on the rational design of high-performance LIBs using 2D-based anode materials.

K2M2(MoO4)3 (M = Ni, Co, Mn): Potential anode materials with high Li-ion storage properties and good low-temperature performance

Owing to the stable three-dimensional network structure, suitable working potential, multi-electronic reaction and high electrochemical activity, molybdate is considered to be a potential anode material for lithium-ion batteries (LIBs) with high energy density and excellent temperature adaptability, while its electrochemical reaction mechanism and limiting factors at low temperature are unclear. Here, three molybdate materials K2M2(MoO4)3/C (M = Ni, Co, Mn) are synthesized and firstly used as anode materials for LIBs. The K2Mn2(MoO4)3/C composite delivers a discharge specific capacity of 1263 mAh·g−1 at 50 mA·g−1 and maintains a reversible capacity of 586 mAh·g−1 after 100 cycles. Moreover, the capacities of the K2Co2(MoO4)3/C composite are as high as 935, 896 and 673 mAh·g−1 at 0, −10, and −20 °C, respectively. The ex-situ X-ray diffraction (XRD) is carried out to understand the electrochemical reaction mechanism. In addition, the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are also applied to obtain the electrochemical reaction mechanism and limiting factors at low temperature. This work deepens the understanding of the low temperature electrochemical reaction mechanism of molybdate anode materials.

Stable anodes for lithium-ion batteries based on tin-containing silicon oxycarbonitride ceramic nanocomposites

Tin nanoparticles are a promising candidate for Li-ion battery anodes to replace carbon materials due to their high theoretical Li-ion storage capacity (994 mAh/g), which is much higher than that of graphite (372 mAh/g). However, the poor cycling stability of tin emerged from large volume expansion, and contraction remains a challenging issue. To overcome these limitations, we designed Sn-containing silicon oxycarbonitride ceramic nanocomposites (Sn/SiOCN) by the chemical reaction of tin acetate with poly(vinyl)silazane Durazane 1800 in ice bath under argon, followed by the pyrolysis of as-obtained precursors at 1000 °C for 3 h under argon atmosphere. The Sn/SiOCN nanocomposites with different Sn contents are tested as anodes for lithium-ion batteries, delivering a high-discharge capacity of ∼320 mAh/g at a current density of 2220 mA/g and extremely long cycling stability even at high charging rates (approximately 90% of the capacity is maintained after 1000 cycles). The outstanding electrochemical performance of Sn/SiOCN nanocomposites can be attributed to the improved charge transfer process due to the incorporation of metallic Sn nanoparticles into the amorphous SiOCN ceramic matrix, as revealed by electrochemical impedance spectroscopy (EIS) characterization. In situ XRD results confirm the formation of lithium-rich alloy phase Li7Sn2 during the lithiation process.

Controllable synthesis of Li3VO4/N doped C nanofibers toward high-capacity and high-rate Li-ion storage

Li3VO4 (LVO) is a promising anode material with comprehensive advantages of energy density and safety performance. However, it suffers from unsatisfactory performance correlating with intrinsic poor reaction kinetics. Herein, morphology-controlled synthesis of LVO/N doped C nanofibers (LVO/NC NFs) is successfully realized via a concise electrospinning approach using low-cost raw materials. The designed LVO/NC NFs show excellent reaction kinetics which result in high pseudocapacitive Li-ion storage throughout cycling, giving rise to ultra-high capacity and prominent rate performance. It delivers discharge capacity of 750 mAh g−1 after 400 cycles at 0.2 A g−1, and 545 mAh g−1 after 900 cycles at 2.0 A g−1. After 2 period rate performance testing from 0.2 to 4.0 A g−1 over 170 cycles, the discharge capacity still reverts to 717 mAh g−1 when the current decreases back to 0.2 A g−1. Tuning the reaction kinetics of LVO via facile electrospinning provides a feasible strategy for constructing high-performance LVO-based anode material.

Hierarchical Co2VO4 yolk-shell microspheres confined by N-doped carbon layer as anode for high-rate lithium-ion batteries

The design of high-performance anodes is crucial for the whole for lithium-ion batteries (LIBs). Binary transition metal oxides (bi-TMOs), especially cobalt vanadates featuring high theoretical lithium storage capacity endow them promising anode materials. However, low electric conductivity as well as tremendous volume change occurring during the process of de−/lithiation restrict their commercialization. Herein, the as-devised novel spinel Co2VO4 yolk-shell microspheres coated with nitrogen-doped carbon shell (Co2VO4@NC) were synthesized by the method of a self-templated solvothermal preparation and following in-situ pyrolysis of polydopamine (PDA) film, which demonstrates excellent properties as anode for LIBs by virtue of the unique spinel structural characteristics, mixed lithium storage mechanism, micro/nanolization of the yolk-shell structure and vital amorphous NC component. In detail, the unique Co2VO4@NC electrode displays the high Li ion storage capacity (1255 mAh g−1 at 0.2 A g−1), the superior cycling stability (1227 mAh g−1 at 0.5 A g−1 after 400 cycles) as well as outstanding reversible capability (remaining 862 mAh g−1 when return to 0.1 A g−1 from 5 A g−1, larger than initial 796 mAh g−1).

Novel borophosphene as a high capacity anode material for Li-ion storage

Looking for high energy density anode materials is still a key factor for high-performance rechargeable lithium-ion batteries (LIBs). Based on the first-principles calculation method, here we identify a novel borophosphene (N-BP) monolayer can serve as a compelling anode material for LIBs. N-BP possesses metallic properties before and after lithiation, which could show good electrical conductivity during the battery cycle. Calculations results exhibit a high storage capacity of 1282.9 ​mA ​h/g, which is better than that of many other reported anode materials. Meanwhile, the calculated low diffusion energy barrier (0.19 ​eV), in combination with the low open circuit voltage (0.17–0.99 ​V), further show the favorable terms of the N-BP as the anode materials. Moreover, molecular dynamical simulation (350 ​K) reveals that the saturated adsorption N-BP keeps excellent stability and Li atoms could freely diffuse on the surface. The light weight and hexagonal structure that composed of B–B and P–P dimers arrangement of the N-BP are attributed to be chiefly responsible for the high Li-ion storage and fast diffusivity. All of these calculations render that the N-BP monolayer is an appropriate Li-ion anticathode material.

Unveiling the stability of Sn/Si/graphite composites for Li-ion storage by physical, electrochemical and computational tools.

Complex materials composed of two and three elements with high Li-ion storage capacity are investigated and tested as lithium-ion battery (LiB) negative electrodes. Namely, anodes containing tin, silicon, and graphite show very good performance because of the large gravimetric and volumetric capacity of silicon and structural support provided by tin and graphite. The performance of the composites during the first cycles was studied using ex situ magic angle spinning (MAS) 7Li Nuclear Magnetic Resonance (NMR), density functional theory (DFT) calculations, and electrochemical techniques. The best performance was obtained for Sn/Si/graphite in a 1 : 1 : 1 proportion, due to an emergent effect of the interaction between Sn and Si. The results suggest a stabilization effect of Sn over Si, providing a physical constraint that prevents Si pulverization. This mechanism ensures good cyclability over more than one hundred cycles, low capacity fading and high specific capacity.

Core-Shell Sn@Sioc Nanocomposite Synthesized Via Spray Pyrolysis for LIBs

Lithium-ion batteries (LIBs) have become promising energy storage devices for the consumer electronics and electric vehicles due to their high energy and power density. Anode materials such as Si, Sn and Ge which are alloying with Li+ ions have been attracted as alternatives to conventional graphite due to their very high theoretical capacities. Among the possible candidates, Sn has been thought to be a great anode material that shows high theoretical Li ion storage capacity of 994mAh g-1 and high electrical conductivity. However, the major drawback of tin based anode is their poor cycling stability because of large volme changes (260% for Li22Sn5) during lithiation resulting in pulverization and loss of electrical contact within the electrode. Especially, the repetitive formation and rupture of solid electrolyte interface (SEI) layer continuously deplete the electrolyte. Nanocrystallization can effectively decrease the absolute volume change of every single particle and mitigated the strain improving the cycling stability of Sn anodes. However, preparation methods of nano-Sn have some negative factors, such as the high cost, complex process and reaggregation after cycling. In order to take full advantage of nano-Sn, many studies introduce suitable matrix. These matrix acts as a buffer agents and avoids side reactions by preventing the direct contact of Sn and electrolyte. The common one is carbon matrix works as a conducting medium and enhances the rate performance of electrode. Another one is active metals including Ge-Sn, Sb-Sn and Ag-Sn that can contribute to the overall capacity of the electrodes and long cycling life. Yet these comes with loss of charge storage capacity or large volume expansion. The quest for suitable matrix with high Li ion storage, low volume expansion and sufficient electronic conductivity is important. In this study, silicon oxycarbide (SiOC) was adapted for Sn based anodes. The SiOC consists of silica tetrahedral SiO2, SiOC glass phase and free carbon. This matrix features a high charge storage capacity (~800mAh g-1), low voulme expansion (~7%) and sufficient mechanical strength contributed by SiO2 domains to accommodate the high volume expansion without capacity fading of Sn anode. In particular, the SiOC can suppress the aggreation of metallic Sn at high temperature remaining nano size. First, we obtained the Sn@SiOC nanocomposite with uniformly coated SiOC layer containing metallic Sn nanoparticle by spray pyrolysis and a subsequent carbonization process. The spray pyrolysis is scalable and facile method to synthesize various nanostructure functional materials via one-pot process. Also it can be easily scaled up for mass production. During the spray pyrolysis process, the tin(II) acetate and diphenylsilanediol (DPSD), the starting materials of Sn and SiOC, can be easily vaporized due to its low boiling point. The tin acetate nucleates first due to lower boiling point than DPSD and formates many clusters. Subsequently, DPSD vapors can be deposited onto the Sn clusters via aerosol assisted chemical vapor depsition (AACVD) mechanism. The deposited DPSD vapors lead to formation of coating layer by nucleation, growth and coagulation. Then, the spray pyrolyzed Sn@SiOC nanocomposite thermally treated at the inert atmosphere for growth of carbon network. This approach yields unifomly coated SiOC matrix with Sn nanoparticles of sizes on the order of 40-50nm. Anodes of the Sn@SiOC nanocomposite demonstrate high capacities and better stability against volume change during lithiation and delithiation cycling.

Synthesis of layered silicon-graphene hetero-structures by wet jet milling for high capacity anodes in Li-ion batteries

While silicon-based negative electrode materials have been extensively studied, to develop high capacity lithium-ion batteries (LIBs), implementing a large-scale production method that can be easily transferred to industry, has been a crucial challenge. Here, a scalable wet-jet milling method was developed to prepare a silicon-graphene hybrid material to be used as negative electrode in LIBs. This synthesized composite, when used as an anode in lithium cells, demonstrated high Li ion storage capacity, long cycling stability and high-rate capability. In particular, the electrode exhibited a reversible discharge capacity exceeding 1763 mAh g−1 after 450 cycles with a capacity retention of 98% and a coulombic efficiency of 99.85% (with a current density of 358 mA g−1). This significantly supersedes the performance of a Si-dominant electrode structures. The capacity fade rate after 450 cycles was only 0.005% per cycle in the 0.05–1 V range. This superior electrochemical performance is ascribed to the highly layered, silicon-graphene porous structure, as investigated via focused ion beam in conjunction with scanning electron microscopy tomography. The hybrid electrode could retain 89% of its porosity (under a current density of 358 mA g−1) after 200 cycles compared with only 35% in a Si-dominant electrode. Moreover, this morphology can not only accommodate the large volume strains from active silicon particles, but also maintains robust electrical connectivity. This confers faster transportation of electrons and ions with significant permeation of electrolyte within the electrode. Physicochemical characterisations were performed to further correlate the electrochemical performance with the microstructural dynamics. The excellent performance of the hybrid material along with the scalability of the synthesizing process is a step forward to realize high capacity/energy density LIBs for multiple device applications.

MoS2 mediated nitrogen enriched composite material for high and fast Li-ion storage

The growth of lithium-ion battery technology is hindered due to its limited ionic conductivity, slow kinetics, and volume expansion. To address these issues, we have developed a composite MoS2@C3N4 by using the nitrogen-rich carbon nitride (C3N4) with a mediator molybdenum disulfide (MoS2). The MoS2@C3N4 composite delivers a reversible capacity of 2283 mAh g−1 at 0.1 C-rate over 500 cycles and exhibits superior rate capability and cycling stability than the C3N4. The enhanced performance is attributed to the utilization of a mediator MoS2 which alters its physicochemical properties, heterojunction formation and the enhanced electrochemical active porous site, consisting of channels for easy penetration of Li-ion.

ZnN and ZnP as novel graphene-like materials with high Li-ion storage capacities

In this work, we employed first-principles density functional theory (DFT) calculations to investigate the dynamical and thermal stability of graphene-like ZnX (X = N, P, As) nanosheets. We moreover analyzed the electronic, mechanical and optical properties of these novel two-dimensional (2D) systems. Acquired phonon dispersion relations reveal the absence of imaginary frequencies and thus confirming the dynamical stability of predicted monolayers. According to ab-initio molecular dynamics results however only ZnN and ZnP exhibit the required thermally stability. The elastic modulus of ZnN, ZnP and ZnAs are estimated to be 31, 21 and 17 N/m, respectively, and the corresponding tensile strengths values are 6.0, 4.9 and 4.0 N/m, respectively. Electronic band structure analysis confirms the metallic electronic character for the predicted monolayers. Results for the optical characteristics also indicate a reflectivity of 100% at extremely low energy levels, which is desirable for photonic and optoelectronic applications. According to our results, graphene-like ZnN and ZnP nanosheets can yield high capacities of 675 and 556 mAh/g for Li-ion storage, respectively. Acquired results confirm the stability and acceptable strength of ZnN and ZnP nanosheets and highlight their attractive application prospects in optical and energy storage systems.

Colloidal Antimony Sulfide Nanoparticles as a High-Performance Anode Material for Li-ion and Na-ion Batteries

To maximize the anodic charge storage capacity of Li-ion and Na-ion batteries (LIBs and SIBs, respectively), the conversion–alloying-type Sb2S3 anode has attracted considerable interest because of its merits of a high theoretical capacity of 946 mAh g−1 and a suitable anodic lithiation/delithiation voltage window of 0.1–2 V vs. Li+/Li. Recent advances in nanostructuring of the Sb2S3 anode provide an effective way of mitigating the challenges of structure conversion and volume expansion upon lithiation/sodiation that severely hinder the Sb2S3 cycling stability. In this context, we report uniformly sized colloidal Sb2S3 nanoparticles (NPs) as a model Sb2S3 anode material for LIBs and SIBs to investigate the effect of the primary particle size on the electrochemical performance of the Sb2S3 anode. We found that compared with microcrystalline Sb2S3, smaller ca. 20–25 nm and ca. 180–200 nm Sb2S3 NPs exhibit enhanced cycling stability as anode materials in both rechargeable LIBs and SIBs. Importantly, for the ca. 20–25 nm Sb2S3 NPs, a high initial Li-ion storage capacity of 742 mAh g−1 was achieved at a current density of 2.4 A g−1. At least 55% of this capacity was retained after 1200 cycles, which is among the most stable performance Sb2S3 anodes for LIBs.