Electrode Materials For Lithium-ion Batteries Research Articles

Metal-organic framework cobalt gallate derived high-voltage carbon coated lithium cobalt oxide cathode and porous carbon supported cobalt oxide anode materials for superior lithium-ion storage

Exploring innovative green synthesis strategies for both cathode and anode materials with improved lithium-ion storage capabilities is of great importance in developing advanced lithium-ion batteries. In this work, a metal-organic framework (MOF) typed sample cobalt gallate (Co-GA), prepared by the direct redox coprecipitation reaction using gallic acid (GA) molecules and metallic cobalt (Co) foils in mild hydrothermal condition, is employed as a precursor for engineering electrode materials for lithium-ion batteries with high atomic efficiency and low environmental impact. Taking the advantages of the unique microstructure and chemical composition of MOF materials, the Co-GA precursor can be easily converted to a rod-like porous carbon framework confined cobalt oxide nanoparticle anode material (Co3O4/RPC) and a thin carbon layer coated nanosized lithium cobalt oxide (LiCoO2) cathode material (LCO/C), respectively, by simply changing the solid-state reaction conditions. In half-cells with metallic lithium as counter electrode, the LCO/C cathode delivers a stable reversible capacity of 189.33 mAh·g−1 after 100 cycles at 200 mA·g−1 and 128.61 mAh·g−1 after 800 cycles at 1000 mA·g−1 in the voltage range of 3.0–4.6 V, while the Co3O4/RPC anode shows a high reversible capacity of 1081.33 mAh·g−1 after 100 cycles at 200 mA·g−1 and 901.09 mAh·g−1 after 400 cycles at 1000 mA·g−1. This work provides a new perspective for green engineering of both anodic and cathodic materials with enhanced lithium-ion storage performances derived from MOF-typed precursors.

Improved cycle stability and high-rate capability of LiNbO3-coated Li3VO4 as anode material for lithium-ion battery

Lithium vanadate (Li3VO4) has garnered considerable attention as an alternative negative electrode material for non-aqueous lithium-ion batteries due to its high capacity, energy efficiency, and stable discharge voltage. Nonetheless, the Li3VO4 material displays a low rate capability, attributed mainly to its poor intrinsic electronic conductivity. Here, we report the synthesis of lithium niobate LiNbO3-coated Li3VO4 (LVO@LNO) using a one-pot sol-gel method. The resulting LVO@LNO demonstrates a high reversible capacity of approximately 530 mAh/g, which is more than double that of free Li3VO4. To explore the effect of the LNO coating process on the morphological and structural properties, Raman, XRD, operando XRD, XPS, SEM and HTEM analyses were conducted. To explain the enhancement of electronic conductivity in our modified material after a LiNbO3 coating, we conducted an Ex-Situ electrochemical impedance (EIS) and Density Functional Theory (DFT) computational study. Additionally, we designed a full cell utilizing a 1 wt% LNO-coated LVO anode and NMC-811 cathode. The cell yielded an output voltage of approximately 2.8 V with a high initial specific capacity of 350 mAh/g versus to the anode, at 1C with a capacity retention of 85 % after 100 cycles.

Pompon Mum-like SiO2/C Nanospheres with High Performance as Anodes for Lithium-Ion Batteries

SiO2 has a much higher theoretical specific capacity (1965 mAh g−1) than graphite, making it a promising anode material for lithium-ion batteries, but its low conductivity and volume expansion problems need to be improved urgently. In this work, pompon mum-like SiO2/C nanospheres with the sandwich and porous nanostructure were obtained by using dendritic fibrous nano silica (DFNS) and glucose as matrix and carbon source, respectively, through hydrothermal, carbonization and etching operations. The influence of SiO2 content and porous structure on its electrochemical performance was discussed in detail. The final results showed that the C/DFNS-6 with a SiO2 content of 6 wt% exhibits the best electrochemical performance as a negative electrode material for lithium-ion batteries due to its optimal specific surface area, porosity, and appropriate SiO2 content. C/DFNS-6 displays a high specific reversible capacity of 986 mAh g−1 at 0.2 A g−1 after 200 cycles, and 529 mAh g−1 at a high current density (1.0 A g−1) after 300 cycles. It also has excellent rate capability, with a reversible capacity that rises from 599 mAh g−1 to 1066 mAh g−1 when the current density drops from 4.0 A g−1 to 0.2 A g−1. These SiO2/C specific pompon mum-like nanospheres with excellent electrochemical performance have great research significance in the field of lithium-ion batteries.

Hierarchical Ni3V2O8@N-Doped Carbon Hollow Double-Shell Microspheres for High-Performance Lithium-Ion Storage.

Transition metal oxides (TMOs) are highly dense in energy and considered as promising anode materials for a new generation of alkaline ion batteries. However, their electrode structure is disrupted due to significant volume changes during charging and discharging, resulting in the short cycle life of batteries. In this paper, the hierarchical Ni3V2O8@N-doped carbon (Ni3V2O8@NC) hollow double-shell microspheres were prepared and used as electrode materials for lithium-ion batteries (LIBs). The utilization efficiency and ion transfer rate of Ni3V2O8 were improved by the hollow microsphere structure formed through nanoparticle self-assembly. Furthermore, the uniform N-doped carbon layer not only enhanced the structural stability of Ni3V2O8, but also improved the overall electrical conductivity of the composite. The Ni3V2O8@NC electrode has an initial discharge capacity of up to 1167.3 mAh g-1 at a current density of 0.3 A g-1, a reversible capacity of up to 726.5 mAh g-1 after 200 cycles, and still has a capacity of 567.6 mAh g-1 after 500 cycles at a current density of 1 A g-1, indicating that the material has good cycle stability and high-rate capability. This work presents new findings on the design and fabrication of complex porous double-shell nanostructures.

Metal-organic frameworks based on ternary transition metal ions for high-performance lithium ion batteries

Metal-organic frameworks (MOFs) materials have been widely researched in energy conversion systems because of porosity and active sites. However, applying MOF as an electrode material remains challenging because of its structural instability. In this work, two novel materials are designed to promote the research of MOFs-based electrode materials for lithium-ion batteries (LIBs). Two ternary metallic ions (Mn2+, Co2+, Ni2+) constituent MOFs with two- and three-dimensional (3D) structures are synthesized by combining with benzene-1,2,3,4,5,6-hexacarboxylate (BHC) ligand via a simple hydrothermal method. The structures of MCN-1 and MCN-2 belong to monoclinic symmetry, C2/c space group. The 3D structure of MCN-2 can enhance the interfacial contact between electrode materials and electrolytes and provide more active sites for the storage of Li+. Electrochemical experiments show that the 3D structure ternary MOF delivers an ultra-high capacity of 807.3 mAh g−1 after 100 cycles at 100 mA g−1, even though a phase transition occurs during the electrochemical process. This superior performance is rationally owing to the synergetic mechanism of intercalation/deintercalation combined with capacitance behavior, which has broad application prospects as anode material.

Comparative Study on the Electrochemical Behaviors of Positive Electrode Materials of Lithium-ion Batteries during Overdischarge

Abstract As lithium-ion battery (LIB) use rises, recycling becomes imperative. Efficiently overdischarging LIBs for residual energy extraction is crucial for safe recycling. Our study analyzes the electrochemical behavior during overdischarge for positive electrode materials, including LiNi0.6Co0.2Mn0.2O2 (NCM622), LiNi0.8Co0.1Mn0.1O2 (NCM811), LiFePO4 (LFP), LiCoO2 (LCO), and LiMn2O4 (LMO). Electrochemical evaluations involve half cells and full cells subjected to constant current overdischarge beyond normal operating ranges. In positive electrode half-cells, a material-dependent conversion reaction was observed, while full cells exhibited similar behaviors during overdischarge to 0 V due to increasing voltage at the negative electrode. Distinct electrochemical variations emerged under forced discharge below 0 V, particularly in the NCM series, showing a gradual voltage decrease to -2 V followed by an internal short circuit. In contrast, LFP, LCO, and LMO swiftly stabilized near 0 V, attributed to the lower initial Coulombic efficiency of NCM materials leading to an early rise in negative electrode potential. To recycle used lithium-ion batteries (LIBs), it's crucial to optimize conditions that ensure both efficient and safe overdischarge, considering the characteristics of positive electrode materials.

Synthesis of Organopolysilazane Nanoparticles as Lithium-Ion Battery Anodes with Superior Electrochemical Performance via the Two-Step Stöber Method.

The Stöber method, a widely utilized sol-gel technique, stands as a green and reliable approach for preparing nanostructures on a large scale. In this study, we employed an enhanced Stöber method to synthesize organopolysilazane nanoparticles (OPSZ NPs), utilizing polysilazane oligomers as the primary precursor material and ammonia as the catalytic agent. By implementing a two-step addition process, control over crucial parameters facilitated the regulation of the nanoparticle size. Generally, maintaining relatively low concentrations of organopolysilazane and catalyst while adjusting the water/acetonitrile ratio can effectively enhance the surface energy of the organopolysilazane, resulting in the uniform formation of small spherical particles. The average particle size of the synthesized OPSZ NPs is about 140 nm, which were monodispersed and characterized by scanning electron microscopy, transmission electron microscopy, and dynamic light scattering. Furthermore, the composition of OPSZ NPs after pyrolysis was confirmed as SiC2.054N0.206O1.631 with 5.44 wt % free carbon structure by X-ray diffraction and energy-dispersive X-ray spectroscopy. Notably, the electrochemical performance assessment of SiCNO NPs as potential electrode materials for lithium-ion batteries exhibited promising outcomes. Specifically, at 1 A g-1 current density, the specific capacity is 585.45 mA h g-1 after 400 cycles, and the minimum capacity attenuation per cycle is only 0.1076 mA h g-1 (0.0172% of the original capacity), which indicates excellent energy storage capacity and cycle stability. In summary, this research contributes to the development of advanced anode materials for next-generation energy storage systems, marking a stride toward sustainable energy solutions.

Tuning the morphology of argan shells-based activated carbon towards applications as an anode for lithium-ion battery

The application of carbonaceous materials other than graphite as an anode for lithium-ion batteries can generate significant advantages, mainly in terms of cost and sustainability while achieving high specific capacities. In this work, we successfully managed to tune the morphology of activated carbon prepared from argan shells to be used as an electrode material for lithium-ion batteries. Both Nanosphere-AC and Honeycomb-AC are obtained from the same precursor. The AC samples were comprehensively characterized using sorption isotherms, scanning electron microscopy, X-ray diffraction and Fourier-transforming infrared spectroscopy. Both materials were tested as anodes for lithium-ion batteries. It was found that Nanosphere-AC permitted great specific capacity (700 mAh.g−1at 50 mAh.g−1) and long-term cycling, showing no apparent capacity fade even after 200 cycles, offering promising application potential. Whereas Honeycomb-AC only achieved 220 mAh.g−1 at 50 mAh.g−1, but still exhibited great long-term cycling performance after 200 cycles and rate capability properties.

Redox process and lithiation mechanism of amorphous vanadium-silicon materials as lithium-ion battery anode

V2O5-TeO2 (VT) is a vanadium-based amorphous lithium-ion battery (LIB) anode material that exhibits a high specific energy, but its low-capacity retention rate and low conductivity limit its widespread application. Different amounts of Si were introduced into VT anode materials to increase their initial discharge capacity and conductivity, which regulated the vanadium redox reaction. 67 V2O5-30TeO2-3Si (VTS3) exhibited the highest conductivity and V4+ content (49.8%). When the Si content was increased, the V4+ content decreased, indicating that Si successfully regulated the redox reaction. The results showed that VTS3 had a high initial discharge capacity of 1187.3 mAh g−1, while that of VT was only 906.5 mAh g−1. After 50 charge-discharge cycles, the retention rates of VT and VTS3 were 15.6% and 25.0%, respectively. After cycling, the precipitation of nanocrystals, especially LiV2O5, from the glass matrix improved the capacity retention of VTS3 by enhancing reversible lithium insertion. The synergy of this disordered-ordered transition improved the discharge capacity and reversibility. Density functional theory (DFT) calculations showed that due to the substitution of Si, the gap between Highest Occupied Molecular Orbital (HOMO) and HOMO-1 was shortened, Li-O electron aggregation was enhanced, the structure was improved, and electronic conductivity was enhanced. At the same time, sufficient Si content increased the initial specific capacity but reduced the retention rate, which was because the volume expansion during the charge-discharge cycle reduced the number of active sites. This work offers a new strategy for preparing LIB electrode materials by introducing Si to regulate redox reactions and precipitate nanocrystals.

Downsizing and coating effects on the electrochemical performance of Mn-doped iron fluorophosphate as cathode material for sodium-ion batteries

Sodium Mn-doped iron fluorophosphate Na2Fe0·5Mn0·5PO4F is a potential positive electrode material for lithium-ion and sodium-ion batteries. This study outlines the synthesis of Na2Fe0·5Mn0·5PO4F powder through a simplified and more accessible production method. The X-rays diffraction (XRD) technique showed a pure phase with monoclinic symmetry (S.G. P21/n). The resulting uncoated material (labeled as NFeMPF) was ball-milled with dopamine hydrochloride (mentioned as dopamine hereafter) as a carbon source to enhance the specific surface and improve its electronic conductivity. Raman spectra confirmed the presence of residual carbon after the pyrolysis process. Thermogravimetric analysis (TGA) demonstrated the stability of Mn-doped iron fluorophosphate up to 1000 °C. Additionally, Mössbauer spectroscopy disclosed structural improvements in the material, indicating the reduction of all Fe(III) when coated with dopamine. The uncoated material discharge capacity when cycled against sodium exhibits reversible capacities of only 80, 67, and 38 mAh/g during the first cycle at C/20, C/16, and C/5, respectively. The coated NFeMPF@D delivered improved capacities of 272 and 202 mAh/g at C/20 and C/16, respectively. This highlights the considerable promise of the investigated phosphate-based electrode material as a cathode composite for the next generation of sodium-ion batteries.

Avocado seed biomass-assisted synthesis of heterostructure bismuth vanadate nanomaterial by combustion method for the application of electrochemical lithium battery storage and supercapacitor

With the global demand for lithium-ion batteries (LIBs), research is focused on developing advanced energy storage materials with high energy and power densities. Hetero-structured nanomaterials have garnered significant interest in energy storage applications based on their unique architecture providing sites for improved electrochemical activity. This work reports a facile single-step combustion synthesis of bismuth vanadate nanoparticles (BVNPs) using avocado seed powder, an economical and eco-friendly fuel source. By optimizing the precursor-to-fuel ratio to 1:1, highly pure phase BVNPs were obtained as characterized via XRD, FT-IR, SEM-EDAX, TEM, UV-DRS, PL, BET, and DLS analyses. When assessed as an electrode material for LIBs, the BVNP1:1 delivered an exceptional initial discharge capacity of 2166 mAhg−1 and a retention of ∼53 mAhg−1 over 90 cycles with 99% Coulombic efficiency. The BVNP1:1 electrode exhibited a maximum specific capacitance of 545.65 mF/cm2 at 2 mA/cm2 current density as a supercapacitor. The combination of scalable green synthesis, excellent phase purity, and superior electrochemical performance makes these BVNPs a promising and sustainable electrode material for forthcoming energy storage technologies to meet the surging energy needs.

Fluorinated boron nitride nanosheet as a high-performance electrode material for ion batteries via first-principles calculations

Developing promising two-dimensional (2D) electrode for ion battery with excellent performances has attracted extensive attention in recent years. Hexagonal boron nitride nanosheet (BNNS) is called “white graphene” due to it has an analogous structure to graphene. BNNS is semiconductor with a relatively large band gap, while it turns into a ferromagnetic half-metal via unilateral fluorination. In this paper, the electronic properties of F-BNNS and its potential application as an electrode material of lithium-ion (LIBs) and sodium ion batteries (SIBs) have been systematically studied via first-principles calculations. It demonstrates that F-BNNS not only exhibits a low diffusion energy barrier but also has a very high storage capacity. The diffusion barriers for Li (Na) diffusing along path I and path II are calculated to be 0.182(0.095) eV and 0.142(0.080) eV, respectively. The low diffusion barriers can guarantee a fast rate during charge/discharge process. Additionally, the storage capacities of F-BNNS are as high as 1244 and 597 mAh g−1 for LIBs and SIBs, which is much higher than that of graphite electrodes (372 mAh g−1). Overall, F-BNNS has promising alternative for an electrode material of LIBs and SIBs in future.

Research on the recycling of waste lithium battery electrode materials using ammonium sulfate roasting

Owing to resource limitations, environmental pollution concerns, and the increasing global demand for lithium-ion battery raw materials, the recycling of discarded electrode materials from lithium-ion batteries has emerged as a prominent research area. Nevertheless, among various types of discarded lithium battery electrode materials, limited research has been conducted on the recycling of ternary electrode materials (LiNixCoyMn1-x-yO2). This study proposes an eco-friendly process for the efficient recovery of valuable metals and carbon from mixed materials of discarded ternary lithium-ion battery electrodes. This study investigated the influence of various roasting using ammonium sulfate and leaching conditions on the conversion and extraction rates of valuable metals. Under the condition of a 3:1 mass ratio of ammonium sulfate to lithium battery electrode mixed material, roasting temperature of 450 °C, roasting time of 30 min, liquid-solid ratio of 20:1, leaching time of 20 min, and leaching temperature of 60 °C, the recovery rates of various valuable metals including Li, Ni, Co, and Mn reached 99.99%. For the above process, the chemical control reaction prevailed in the initial 10 min of the roasting reaction, succeeded by the dominance of diffusion control reaction in the subsequent 20 min. In the leaching process, the chemical control reaction governed the first 2 min, succeeded by diffusion control reaction for the next 18 min. Analysis of the reaction's macroscopic and microscopic mechanisms reveals that ammonium sulfate roasting of waste ternary lithium-ion batteries constitutes a typical liquid-solid reaction. In the molten state, NH4+ decomposition releases high-energy H+ ions that break the bonds between metals and oxygen. Consequently, metal atoms from the waste battery's crystal structure combine with ammonium sulfate's sulfate groups, forming various metal sulfates. This paper establishes an eco-friendly process for the efficient recovery of valuable metals by employing the ammonium sulfate roasting method to convert valuable metals in discarded electrode mixed materials into water-soluble sulfates.

On the prospects of using B4C3 as a potential electrode material for lithium-ion batteries

Lithium-ion batteries (LIBs) served as promising energy-storage solutions for various applications, from portable electronics to electric-vehicles. There is a growing demand for high-performance electrode materials with improved storage capacity, high cyclic stability, low energy barriers, reduced material toxicity, and cost-effectiveness. This study explores the electrochemical feasibility of B4C3 monolayer as an anode material for LIBs using density functional theory (DFT) computations and molecular dynamic (MD) simulations. The optimum anodic nature of B4C3 is reported based on its structural, electronic, diffusion, storage behaviour, and lithiation studies. The adsorption sites for Li atoms were systematically explored. The lithium saturation requires the adsorption of 29 lithium atoms on B4C3 while preserving stability confirmed by Ab-initio molecular dynamics (AIMD) simulations and ensuring favorable transport characteristics during the lithiation process based on Hirshfeld charge analysis and steric interaction calculations. The storage capacity of the host B4C3 is calculated as 2770.2 mAhg−1 which is notably higher than that of graphite anode. The computed value of open circuit voltage is 0.62 V per Li. The value of diffusion coefficient and ionic conductivity σ is 0.7 × 10−8 m2/s and 0.78 S/m respectively which predicts excellent overall anodic operation of the material. The transition barrier of the Li ions in the material is determined through Cl-NEB, which shows the lowest value of 0.06 eV along the x-axis.

Endogenous Interfacial Mo-C/N-Mo-S Bonding Regulates the Active Mo Sites for Maximized Li+ Storage Areal Capacity.

Active sites, mass loading, and Li-ion diffusion coefficient are the benchmarks for boosting the areal capacity and storage capability of electrode materials for lithium-ion batteries. However, simultaneously modulating these criteria to achieve high areal capacity in LIBs remains challenging. Herein, MoS2 is considered as a suitable electroactive host material for reversible Li-ion storage and establish an endogenous multi-heterojunction strategy with interfacial Mo-C/N-Mo-S coordination bonding that enables the concurrent regulation of these benchmarks. This strategy involves architecting 3D integrated conductive nanostructured frameworks composed of Mo2 C-MoN@MoS2 on carbon cloth (denoted as C/MMMS) and refining the sluggish kinetics in the MoS2 -based anodes. Benefiting from the rich hetero-interface active sites, optimized Li adsorption energy, and low diffusion barrier, C/MMMS reaches a mass loading of 12.11mgcm-2 and showcases high areal capacity and remarkable rate capability of 9.6mAhcm-2 @0.4mAcm-2 and 2.7mAhcm-2 @6.0mA cm-2 , respectively, alongside excellent stability after 500 electrochemical cycles. Moreover, this work not only affirms the outstanding performance of the optimized C/MMMS as an anode material for supercapacitors, underscoring its bifunctionality but also offers valuable insight into developing endogenous transition metal compound electrodes with high mass loading for the next-generation high areal capacity energy storage devices.

MOF-derived cobalt nanoparticles in silicon suboxide-based anodes for enhanced lithium storage

The ultra-high theoretical capacity of silicon-based (Si) materials makes them promising anode materials for high energy density lithium-ion batteries. Unfortunately, the dramatic volume change (∼300%) and low electrical conductivity of silicon have severely hindered the commercial use of silicon anodes. Silicon suboxide (SiOx) is one of the ideal candidates for high energy density batteries due to its reduced swelling and lower cost as compared to silicon. However, it remains a huge challenge to address the low conductivity, low (initial) coulombic efficiency and apparent volume effects of SiOx. In this paper, SiOx/Co@C composite anode materials loaded with metal Co nanoparticles were uniformly and efficiently prepared by using 3-aminopropyl triethoxysilane (APTES) as silicon source and Co-MOF as Co source via molecular self-assembly strategy. The experimental results and density functional theory (DFT) calculation showed that the catalytic action of embedded Co nanoparticles had activated the silico-oxygen bond of SiOx and the irreversible product Li2O, thereby improving the initial coulombic efficiency (ICE) and enhancing the reversible capacity. At the same time, the metal Co with mechanical rigidity and electrical conductivity alleviated the volume fluctuation during alloying and improved the charge transfer capacity and ion transport rate of the composite. When compared with SiOx@C anodes, SiOx/Co@C-600 composites showed higher initial CE, superior cyclic stability and good rate performance. In particular, the successful matching of the anode with the lithium iron phosphate (LFP) cathode in full cell systems validated the possibility of its practical application. This work provides important insights into the application of Si-based materials in lithium-ion battery electrode materials and the development of high energy density batteries.

Phase Engineering via Aluminum Doping Enhances the Electrochemical Stability of Lithium-Rich Cobalt-Free Layered Oxides for Lithium-Ion Batteries.

Lithium-rich, cobalt-free oxides are promising potential positive electrode materials for lithium-ion batteries because of their high energy density, lower cost, and reduced environmental and ethical concerns. However, their commercial breakthrough is hindered because of their subpar electrochemical stability. This work studies the effect of aluminum doping on Li1.26 Ni0.15 Mn0.61 O2 as a lithium-rich, cobalt-free layered oxide. Al doping suppresses voltage fade and improves the capacity retention from 46% for Li1.26 Ni0.15 Mn0.61 O2 to 67% for Li1.26 Ni0.15 Mn0.56 Al0.05 O2 after 250 cycles at 0.2C. The undoped material has a monoclinic Li2 MnO3 -type structure with spinel on the particle edges. In contrast, Al-doped materials (Li1.26 Ni0.15 Mn0.61-x Alx O2 ) consist of a more stable rhombohedral phase at the particle edges, with a monoclinic phase core. For this core-shell structure, the formation of Mn3+ is suppressed along with the material's decomposition to a disordered spinel, and the amount of the rhombohedral phase content increases during galvanostatic cycling. Whereas previous studies generally provided qualitative insight into the degradation mechanisms during electrochemical cycling, this work provides quantitative information on the stabilizing effect of the rhombohedral shell in the doped sample. As such, this study provides fundamental insight into the mechanisms through which Al doping increases the electrochemical stability of lithium-rich cobalt-free layered oxides.

Spatially confined synthesis of TiNb2O7 quantum dots onto mesoporous carbon and Ti3C2TX MXene for boosting lithium storage

TiNb2O7 has been emerged as one of the most promising electrode materials for high-energy lithium-ion batteries. However, limited by the slow electron/ion transport kinetics, and insufficient active sites in the bulk structure, the TiNb2O7 electrode still suffers from unsatisfactory lithium storage performance. Herein, we demonstrate a spatially confined strategy toward a novel TiNb2O7-NMC/MXene composite through a triblock copolymer-directed one-pot solvothermal route, where TiNb2O7 quantum dots with a particle size of 2–3 nm are evenly embedded into N-doped mesoporous carbon (NMC) and Ti3C2TX MXene. Impressively, the as-prepared TiNb2O7-NMC/MXene anode exhibits a high reversible capacity (486.2 mAh g−1 at 0.1 A g−1 after 100 cycles) and long cycle lifespan (363.4 mAh g−1 at ss1 A g−1 after 500 cycles). Both experimental and theorical results further demonstrate that such a superior lithium storage performance is mainly ascribed to the synergistic effect among 0D TiNb2O7 quantum dots, 2D Ti3C2TX MXene nanosheets, and N-doped mesoporous carbon. The strategy presented also opens up new horizon for space-confined preparation of high-performance electrode materials.

Revealing the Dynamic Lithiation Process of Copper Disulfide by in Situ TEM.

Transition metal oxides, fluorides, and sulfides are extensively studied as candidate electrode materials for lithium-ion batteries driven by the urgency of developing next-generation higher energy density lithium batteries. These conversion-type electrode materials often require nanosized active materials to enable a "smooth" lithiation and de-lithiation process during charge/discharge cycles, determined by their size, structure, and phase. Herein, the structural and chemical changes of Copper Disulfide (CuS2 ) hollow nanoparticles during the lithiation process through an in situ transmission electron microscopy (TEM) method are investigated. The study finds the hollow structure of CuS2 facilitates the quick formation of fluidic Li2 S "drops," accompanied by a de-sulfurization to the Cu7 S4 phase. Meanwhile, the metallic Cu phase emerges as fine nanoparticles and grows into nano-strips, which are embedded in the Li2 S/Cu7 S4 matrix. These complex nanostructured phases and their spatial distribution can lead to a low de-lithiation barrier, enabling fast reaction kinetics.

Theoretical prediction of B5C8 monolayer as a high-performance anode material for lithium-ion batteries

The demand for high-performance energy storage systems has stimulated intensive research on high-performance electrode materials for lithium-ion batteries (LIBs). Two-dimensional (2D) materials have emerged as promising candidates for anode materials due to their unique structural and physicochemical properties. Based on first-principles calculations, we propose a 2D material, B5C8 monolayer, as an excellent anode material for LIBs. B5C8 monolayer exhibits inherent metallicity and outstanding dynamic, mechanical, and thermal stability. Furthermore, B5C8 monolayer shows not only remarkably high storage capacity (2856 mA h g−1) but also low barrier energy (0.25 eV) and small volume change (2.1%). More importantly, B5C8 possesses strong wettability toward commonly used electrolytes in LIBs, namely, solvent molecules and metal salts, indicating prime compatibility. Based on the above distinguished findings, we hope B5C8 monolayer can act as a well-balanced performance anode material for LIBs.