Self-Assembled CoS Nanoflowers Wrapped in Reduced Graphene Oxides as the High-Performance Anode Materials for Sodium-Ion Batteries

ZnS/CoS@C Derived from ZIF-8/67 Rhombohedral Dodecahedron Dispersed on Graphene as High-Performance Anode for Sodium-Ion Batteries

Metal sulfides are highly promising anode materials for sodium-ion batteries due to their high theoretical capacity and ease of designing morphology and structure. In this study, a metal-organic framework (ZIF-8/67 dodecahedron) was used as a precursor due to its large specific surface area, adjustable pore structure, morphology, composition, and multiple active sites in electrochemical reactions. The ZIF-8/67/GO was synthesized using a water bath method by introducing graphene; the dispersibility of ZIF-8/67 was improved, the conductivity increased, and the volume expansion phenomenon that occurs during the electrochemical deintercalation of sodium was prevented. Furthermore, vulcanization was carried out to obtain ZnS/CoS@C/rGO composite materials, which were tested for their electrochemical properties. The results showed that the ZnS/CoS@C/rGO composite was successfully synthesized, with dodecahedrons dispersed in large graphene layers. It maintained a capacity of 414.8 mAh g-1 after cycling at a current density of 200 mA g-1 for 70 times, exhibiting stable rate performance with a reversible capacity of 308.0 mAh g-1 at a high current of 2 A g-1. The excellent rate performance of the composite is attributed to its partial pseudocapacitive contribution. The calculation of the diffusion coefficient of Na+ indicates that the rapid sodium ion migration rate of this composite material is also one of the reasons for its excellent performance. This study highlights the broad application prospects of metal-organic framework-derived metal sulfides as anode materials for sodium-ion batteries.

Recent advances in nanoflowers: compositional and structural diversification for potential applications

In recent years, nanoscience and nanotechnology have emerged as promising fields in materials science. Spectroscopic techniques like scanning tunneling microscopy and atomic force microscopy have revolutionized the characterization, manipulation, and size control of nanomaterials, enabling the creation of diverse materials such as fullerenes, graphene, nanotubes, nanofibers, nanorods, nanowires, nanoparticles, nanocones, and nanosheets. Among these nanomaterials, there has been considerable interest in flower-shaped hierarchical 3D nanostructures, known as nanoflowers. These structures offer advantages like a higher surface-to-volume ratio compared to spherical nanoparticles, cost-effectiveness, and environmentally friendly preparation methods. Researchers have explored various applications of 3D nanostructures with unique morphologies derived from different nanoflowers. The nanoflowers are classified as organic, inorganic and hybrid, and the hybrids are a combination thereof, and most research studies of the nanoflowers have been focused on biomedical applications. Intriguingly, among them, inorganic nanoflowers have been studied extensively in various areas, such as electro, photo, and chemical catalysis, sensors, supercapacitors, and batteries, owing to their high catalytic efficiency and optical characteristics, which arise from their composition, crystal structure, and local surface plasmon resonance (LSPR). Despite the significant interest in inorganic nanoflowers, comprehensive reviews on this topic have been scarce until now. This is the first review focusing on inorganic nanoflowers for applications in electro, photo, and chemical catalysts, sensors, supercapacitors, and batteries. Since the early 2000s, more than 350 papers have been published on this topic with many ongoing research projects. This review categorizes the reported inorganic nanoflowers into four groups based on their composition and structure: metal, metal oxide, alloy, and other nanoflowers, including silica, metal-metal oxide, core-shell, doped, coated, nitride, sulfide, phosphide, selenide, and telluride nanoflowers. The review thoroughly discusses the preparation methods, conditions for morphology and size control, mechanisms, characteristics, and potential applications of these nanoflowers, aiming to facilitate future research and promote highly effective and synergistic applications in various fields.

Electrolyte Engineering on Performance Enhancement of NiCo2 S4 Anode for Sodium Storage

NiCo₂ S₄ is an attractive anode for sodium-ion batteries (SIBs) due to its high capacity and excellent redox reversibility. Practical deployment of NiCo₂ S₄ electrode in SIBs, however, is still hindered by the inferior capacity and unsatisfactory cycling performance, which result from the mismatch between the electrolyte chemistry and electrode. Herein, a functional electrolyte containing 1.0 m NaCF₃ SO₃ in diethylene glycol dimethyl ether (DEGDME) (1.0 m NaCF₃ SO₃ -DEGDME) is developed, which can be readily used for NiCo₂ S₄ anode with high initial coulomb efficiency (96.2%), enhanced cycling performance, and boosted capacities (341.7 mA h g^-1 after 250 continuous cycles at the current density of 200 mA g^-1 ). The electrochemical tests and related phase characterization combined with density functional theory (DFT) calculation indicate the ether-based electrolyte is more suitable for the NiCo₂ S₄ anode in SIBs due to the formation of a stable electrode-electrolyte interface. Additionally, the importance of the voltage window is also demonstrated to further optimize the electrochemical performance of the NiCo₂ S₄ electrode. The formation of sulfide intermediates during charging and discharging is predicted by combining DFT and verified by in situ XRD and HRTEM. The findings indicate that electrolyte engineering would be an effective way of performance enhancement for sulfides in practical SIBs.

Improved lithium-ion battery performance by introducing oxygen-containing functional groups by plasma treatment

Metal sulfides are often used as cathode materials for lithium-ion batteries (LIBs) owing to their high theoretical specific capacity; however, excessively fast capacity decay during charging/discharging and rapid shedding during cycling limits their practical application in batteries. In this study, we proposed a strategy using plasma treatment combined with the solvothermal method to prepare cobalt sulfide (Co_1-xS)-carbon nanofibers (CNFs) composite. The plasma treatment could introduce oxygen-containing polar groups and defects, which could improve the hydrophilicity of the CNFs for the growth of the Co_1-xS, thereby increasing the specific capacity of the composite electrode. The results show that the composite electrode present a high discharge specific capacity (839 mAh g^-1at a current density of 100 mA g^-1) and good cycle stability (the capacity retention rate almost 100% at 2000 mA g^-1after 500 cycles), attributing to the high conductivity of the CNFs. This study proves the application of plasma treatment and simple vulcanization method in high-performance LIBs.

Boosting Transport Kinetics of Cobalt Sulfides Yolk-Shell Spheres by Anion Doping for Advanced Lithium and Sodium Storage

Cobalt sulfides have been popularly used in energy storage because of their high theoretical capacity and abundant redox reactions. However, poor reaction kinetics, rapid capacity decay, and severe polarization owing to volume changes during electrochemical reaction are still huge challenges for cobalt sulfides in practical applications. Herein, cobalt sulfide yolk-shell spheres were synthesized by phosphorus doping (P-CoS) to stabilize the structure of cobalt sulfides and improve their electronic/ion conductivity. Kinetic tests and density functional theory calculations confirm that the introduction of phosphorus into cobalt sulfides greatly reduces the diffusion barrier of Li⁺ in the intrinsic structure, thereby improving the reaction kinetics of electrode materials during the Li⁺ insertion/extraction process. In consequence, the P-CoS electrode delivers a high lithium storage capacity (781 mAh g^-1 after 100 cycles at 0.2 A g^-1 ), excellent rate capability (489 mAh g^-1 at 10 A g^-1 ), and outstanding cycling stability (no significant capacity decay over 4000 cycles at 5 A g^-1 ). Especially for sodium-ion battery application, the P-CoS electrode expresses a striking capacity of approximately 260 mAh g^-1 at 2 A g^-1 after 900 cycles.

Synergizing Phase and Cavity in CoMoOx Sy Yolk-Shell Anodes to Co-Enhance Capacity and Rate Capability in Sodium Storage

Sodium-ion batteries (SIBs) have been recognized as the promising alternatives to lithium-ion batteries for large-scale applications owing to their abundant sodium resource. Currently, one significant challenge for SIBs is to explore feasible anodes with high specific capacity and reversible pulverization-free Na⁺ insertion/extraction. Herein, a facile co-engineering on polymorph phases and cavity structures is developed based on CoMo-glycerate by scalable solvothermal sulfidation. The optimized strategy enables the construction of CoMoO_x S_y with synergized partially sulfidized amorphous phase and yolk-shell confined cavity. When developed as anodes for SIBs, such CoMoO_x S_y electrodes deliver a high reversible capacity of 479.4 mA h g^-1 at 200 mA g^-1 after 100 cycles and a high rate capacity of 435.2 mA h g^-1 even at 2000 mA g^-1 , demonstrating superior capacity and rate capability. These are attributed to the unique dual merits of the anodes, that is, the elastic bountiful reaction pathways favored by the sulfidation-induced amorphous phase and the sodiation/desodiation accommodatable space benefits from the yolk-shell cavity. Such yolk-shell nano-battery materials are merited with co-tunable phases and structures, facile scalable fabrication, and excellent capacity and rate capability in sodium storage. This provides an opportunity to develop advanced practical electrochemical sodium storage in the future.

CoS nanosheets wrapping on bowl-like hollow carbon spheres with enhanced compact density for sodium-ion batteries

Transition metal sulfides have long suffered from poor conductivity and large volume change when valued as an anode material for sodium-ion batteries. Hollow carbon nanohybrids prove to be the highly effective materials to solve these problems. While the low inherent compact density of hollow material leads to the low volume energy density of batteries. Herein, we employ a bowl-like hollow carbon sphere as the carbon substrate to promote compact density. Owing to the smaller cavity size and compact arrangement of bowl-like hollow spheres, the well-designed CoS@bowl-like hollow carbon spheres ultimately upgrade the compact density to 122% compare with that of CoS@hollow carbon spheres. Meanwhile, the hierarchical and interconnected CoS nanosheets tightly wrapped on the surface of the spheres, which can not only prevent self-aggregation of CoS but also provide shorter transmission path of both ions and electronics. This novel CoS@bowl-like hollow carbon spheres exhibit a good cycling performance: a reversible capacity of 543 mAh g^-1 after 400 cycles and 452 mAh g^-1 after 1000 cycles at 1 A g^-1. The Na₃V₂(PO₄)₃//CoS@ bowl-like hollow carbon spheres full cell shows a reversible capacity of 320 mAh g^-1 at 0.5 A g^-1.

N-Doped C@Zn3 B2 O6 as a Low Cost and Environmentally Friendly Anode Material for Na-Ion Batteries: High Performance and New Reaction Mechanism

Na-ion batteries (NIBs) are ideal candidates for solving the problem of large-scale energy storage, due to the worldwide sodium resource, but the efforts in exploring and synthesizing low-cost and eco-friendly anode materials with convenient technologies and low-cost raw materials are still insufficient. Herein, with the assistance of a simple calcination method and common raw materials, the environmentally friendly and nontoxic N-doped C@Zn₃ B₂ O₆ composite is directly synthesized and proved to be a potential anode material for NIBs. The composite demonstrates a high reversible charge capacity of 446.2 mAh g^-1 and a safe and suitable average voltage of 0.69 V, together with application potential in full cells (discharge capacity of 98.4 mAh g^-1 and long cycle performance of 300 cycles at 1000 mA g^-1 ). In addition, the sodium-ion storage mechanism of N-doped C@Zn₃ B₂ O₆ is subsequently studied through air-insulated ex situ characterizations of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared (FT-IR) spectroscopy, and is found to be rather different from previous reports on borate anode materials for NIBs and lithium-ion batteries. The reaction mechanism is deduced and proposed as: Zn₃ B₂ O₆ + 6Na⁺ + 6e^- ⇋ 3Zn + B₂ O₃ ∙ 3Na₂ O, which indicates that the generated boracic phase is electrochemically active and participates in the later discharge/charge progress.

Synthesis and electrochemical performance of NaV3O8 nanobelts for Li/Na-ion batteries and aqueous zinc-ion batteries

NaV₃O₈ nanobelts were successfully synthesized for Li/Na-ion batteries and rechargeable aqueous zinc-ion batteries (ZIBs) by a facile hydrothermal reaction and subsequent thermal transformation. Compared to the electrochemical performance of LIBs and NIBs, NaV₃O₈ nanobelt cathode materials in ZIBs have shown excellent electrochemical performance, including high specific capacity of 421 mA h g⁻¹ at 100 mA g⁻¹ and good cycle stability with a capacity retention of 94% over 500 cycles at 5 A g⁻¹. The good diffusion coefficients and high surface capacity of NaV₃O₈ nanobelts in ZIBs were in favor of fast Zn²⁺ intercalation and long-term cycle stability.

Compared to the electrochemical performance for LIBs and NIBs, NaV₃O₈ nanobelts electrode for ZIBs shows excellent electrochemical performance, including high specific capacity of 421 mA h g⁻¹ at 100 mA g⁻¹, good rate performance and cycle performance.

Facile fabrication of CuS microflower as a highly durable sodium-ion battery anode

CuS micro-flower was synthesized by dealloying and adopted as an anode in SIB with high rate and stable cycle performances.

Unique CoS hierarchitectures for high-performance lithium ion batteries

Lantern-like CoS hierarchitectures, having a perfect crystal structure, a high specific surface area and lots of nanoscale 3D channels, are synthesized.