A one-step approach towards carbon-encapsulated hollow tin nanoparticles and their application in lithium batteries

Nanographenes and Graphene Nanoribbons as Multitalents of Present and Future Materials Science

As cut-outs from a graphene sheet, nanographenes (NGs) and graphene nanoribbons (GNRs) are ideal cases with which to connect the world of molecules with that of bulk carbon materials. While various top-down approaches have been developed to produce such nanostructures in high yields, in the present perspective, precision structural control is emphasized for the length, width, and edge structures of NGs and GNRs achieved by modern solution and on-surface syntheses. Their structural possibilities have been further extended from "flatland" to the three-dimensional world, where chirality and handedness are the jewels in the crown. In addition to properties exhibited at the molecular level, self-assembly and thin-film structures cannot be neglected, which emphasizes the importance of processing techniques. With the rich toolkit of chemistry in hand, NGs and GNRs can be endowed with versatile properties and functions ranging from stimulated emission to spintronics and from bioimaging to energy storage, thus demonstrating their multitalents in present and future materials science.

One-Pot Synthesis of High-Performance Tin Chalcogenides/C Anodes for Li-Ion Batteries

Tin chalcogenides are considered as promising anode materials for lithium-ion batteries (LIBs) due to their high theoretical lithium-storage capacity. Herein, we have successfully synthesized the composites of tin chalcogenides and graphite, that is, SnS/C, SnSe/C, and SnS_0.5Se_0.5/C, via a simple one-pot solid-state method. During the electrochemical test, they exhibit excellent lithium-storage ability and cyclic performance as the anode electrodes of LIBs due to the introduction of carbon. In particular, (i) SnS/C displayed a high specific capacity of 875 mAh g^-1 at 0.2 A g^-1 over 200 cycles; (ii) SnSe/C presents 734 mAh g^-1 at 0.2 A g^-1 after 100 cycles, and it delivers 690 mAh g^-1 at 1.0 A g^-1 over 300 cycles; and (iii) the SnS_0.5Se_0.5/C composite electrode delivers a specific capacity of 643 mAh g^-1 at 0.5 A g^-1 over 150 cycles. Furthermore, another series of tin-based composites have also been successfully fabricated (i.e., Sn/C, SnS₂/C, SnSe₂/C, and SnTe/C), showing the general applicability of the synthetic route applied here. Our synthetic approach demonstrates a promising route for the large-scale production of high-performance tin chalcogenides/C anode materials for LIBs and other battery systems (e.g., Na-ion and K-ion batteries).

Computational Approach To Reveal the Structural Stability and Electronic Properties of Lithiated M/CNT (M = Si, Ge) Nanocomposites as Anodes for Lithium-Ion Batteries

This work is motivated to explore the structural stability and electronic and electrochemical properties of nanocomposites of M₄Li _n (M = Si and Ge)-carbon nanotube (CNT) by employing first-principles density functional theory calculations. By analyzing the structural stability of various M₄Li _n (n = 0-10) clusters, it is revealed that a tetrahedron-shaped M₄Li₄ Zintl cluster is found to be highly stable. Our study on the interaction between the lithiated clusters and CNT illustrates that the charge transfer from the former to latter plays a pivotal role in stabilizing these nanocomposites. The structural stability of those nanocomposites arises as a consequence of bonding between lithiated clusters and CNT, which is mediated through the cation-π interaction. The strength of the interaction between them is well reflected in electronic structure calculations by shifting the energy levels with respect to the Fermi energy. Further, the electrochemical properties of these nanocomposites are explored by forming an assembly of the cluster-inserted CNT. The calculated average intercalation voltage of the systems is found to be low (maximum ∼1.0 V for M = Si and 1.05 V for M = Ge), which demonstrates their anodic behavior.

Monodisperse tin nanoparticles and hollow tin oxide nanospheres as anode materials for high performance lithium ion batteries

Monodisperse Sn nanoparticles and hollow/amorphous SnO_x nanospheres are prepared via a facile colloidal method, and they exhibit good electrochemical performances as anode materials in lithium ion batteries.

Yolk–shell structured SnSe as a high-performance anode for Na-ion batteries

Yolk–shell structured SnSe nanoparticles have been investigated as anode materials in Na-ion batteries for the first time, and exhibit excellent Na⁺ storage performance.

Valorisation of post-sorption materials: Opportunities, strategies, and challenges

Adsorption is a facile, economic, eco-friendly and low-energy requiring technology that aims to separate diverse compounds (ions and molecules) from one phase to another using a wide variety of adsorbent materials. To date, this technology has been used most often for removal/recovery of pollutants from aqueous solutions; however, emerging post-sorption technologies are now enabling the manufacture of value-added key adsorption products that can subsequently be used for (i) fertilizers, (ii) catalysis, (iii) carbonaceous metal nanoparticle synthesis, (iv) feed additives, and (v) biologically active compounds. These new strategies ensure the sustainable valorisation of post-sorption materials as an economically viable alternative to the engineering of other green chemical products because of the ecological affability, biocompatibility, and widespread accessibility of post-sorption materials. Fertilizers and feed additives manufactured using sorption technology contain elements such as N, P, Cu, Mn, and Zn, which improve soil fertility and provide essential nutrients to animals and humans. This green and effective approach to managing post-sorption materials is an important step in reaching the global goals of sustainability and healthy human nutrition. Post-sorbents have also been utilized for the harvesting of metal nanoparticles via modern catalytic pyrolysis techniques. The resulting materials exhibited a high surface area (>1000m²/g) and are further used as catalysts and adsorbents. Together with the above possibilities, energy production from post-sorbents is under exploration. Many of the vital 3E (energy, environment, and economy) problems can be addressed using post-sorption materials. In this review, we summarize a new generation of applications of post-adsorbents as value-added green chemical products. At the end of each section, scientific challenges, further opportunities, and issues related to toxicity are discussed. We believe this critical evaluation not only delivers essential contextual information to researchers in the field but also stimulates new ideas and applications to further advance post-sorbent applications.

Molecular Lifting, Twisting, and Curling during Metal-Assisted Polycyclic Hydrocarbon Dehydrogenation

The atomistic understanding of the dissociation mechanisms for large molecules adsorbed on surfaces is still a challenge in heterogeneous catalysis. This is especially true for polycyclic aromatic hydrocarbons, which represent an important class of organic compounds used to produce novel graphene-based architectures. Here, we show that coronene molecules adsorbed on Ir(111) undergo major conformational changes during dissociation. They first tilt upward with respect to the surface, still keeping their planar configuration, and subsequently experience a rotation, which changes the molecular axis orientation. Upon lifting, the internal C-C strain is initially relieved; as the dehydrogenation proceeds, the molecules experience a progressive increase in the average interatomic distance and gradually settle to form dome-shaped nanographene flakes. Our results provide important insight into the complex mechanism of molecular breakup, which could have implications in the synthesis of new carbon-based nanostructured materials.

Cu@Sn nanostructures based on light-weight current collectors for superior reversible lithium ion storage

The welding process makes good progress to reduce the sheet resistance, which ensures the effective diffusion of Li-ions and electrons.

Facile synthesis of ultrathin, undersized MoS2/graphene for lithium-ion battery anodes

Ultrathin (∼5 layers), undersized (130–160 nm in size) MoS₂/graphene composites are fabricated by a facile acetic acid assisted hydrothermal route.

Novel hollow and yolk–shell structured periodic mesoporous polymer nanoparticles

Novel hollow and yolk–shell structured periodic mesoporous polymer nanoparticles were prepared by the development of an efficient reactive interface-guided co-assembly approach.

Freestanding carbon-coated CNT/Sn(O2) coaxial sponges with enhanced lithium-ion storage capability

Carbon-coated, carbon nanotube (CNT)/tin(oxide) spongy coaxial nanostructures, CNT/Sn(O(2))@C, with large areal mass loadings have been developed by employing a three-dimensional CNT sponge as a backbone. The freestanding spongy coaxial nano-architecture demonstrates exceptional electrochemical characteristics of tin-based anode materials with appropriate structural engineering for energy storage application.

Growth of nickel silicate nanoplates on reduced graphene oxide as layered nanocomposites for highly reversible lithium storage

The combination of active materials with electrically conductive carbon materials and their contact efficiency are crucial for improving the electrochemical performances of active materials. Here, nickel silicate (NiSiOx) nanoplates are planted in situ on the surface of reduced graphene oxide (RGO) nanosheets to form a two dimensional face-to-face nanocomposite of NiSiOx/RGO for lithium storage. The face-to-face structure enhances the contact efficiency of NiSiOx with RGO, and thus leads to a higher reversible capacity and better rate performance of the NiSiOx/RGO nanocomposite than both carbon nanotube (CNT)@NiSiOx nanocables and NiSiOx. The layered NiSiOx/RGO nanocomposite exhibits a high reversible specific capacity of 797 mA h g(-1), which is 62% and 806% higher than those of CNT@NiSiOx nanocables and NiSiOx alone, respectively.

Preparation of a porous Sn@C nanocomposite as a high-performance anode material for lithium-ion batteries

A porous Sn@C nanocomposite was prepared via a facile hydrothermal method combined with a simple post-calcination process, using stannous octoate as the Sn source and glucose as the C source. The as-prepared Sn@C nanocomposite exhibited excellent electrochemical behavior with a high reversible capacity, long cycle life and good rate capability when used as an anode material for lithium ion batteries.

Drastically Enhanced High-Rate Performance of Carbon-Coated LiFePO4 Nanorods Using a Green Chemical Vapor Deposition (CVD) Method for Lithium Ion Battery: A Selective Carbon Coating Process

Application of LiFePO4 (LFP) to large current power supplies is greatly hindered by its poor electrical conductivity (10(-9) S cm(-1)) and sluggish Li+ transport. Carbon coating is considered to be necessary for improving its interparticle electronic conductivity and thus electrochemical performance. Here, we proposed a novel, green, low cost and controllable CVD approach using solid glucose as carbon source which can be extended to most cathode and anode materials in need of carbon coating. Hydrothermally synthesized LFP nanorods with optimized thickness of carbon coated by this recipe are shown to have superb high-rate performance, high energy, and power densities, as well as long high-rate cycle lifetime. For 200 C (18s) charge and discharge, the discharge capacity and voltage are 89.69 mAh g(-1) and 3.030 V, respectively, and the energy and power densities are 271.80 Wh kg(-1) and 54.36 kW kg(-1), respectively. The capacity retention of 93.0%, and the energy and power density retention of 93.6% after 500 cycles at 100 C were achieved. Compared to the conventional carbon coating through direct mixing with glucose (or other organic substances) followed by annealing (DMGA), the carbon phase coated using this CVD recipe is of higher quality and better uniformity. Undoubtedly, this approach enhances significantly the electrochemical performance of high power LFP and thus broadens greatly the prospect of its applications to large current power supplies such as electric and hybrid electric vehicles.

Sn–Co nanoparticles encapsulated in grid-shell carbon spheres, applied as a high-performance anode material for lithium-ion batteries

The Sn–Co nanoparticles encapsulated in grid-shell carbon spheres showed high capacity, good rate performance and excellent capacity retention.

Co3O4/C/graphene nanocomposites as novel anode materials for high capacity lithium ion batteries

A binder-free slurry of a Co₃O₄/C/graphene nanocomposite with “soft” interfaces between carbon materials and metal oxides has been successfully prepared in this work, and applied as a superior anode material for giant-performance LIBs.

Nanoflakes-assembled three-dimensional hollow-porous v2 o5 as lithium storage cathodes with high-rate capacity

Three-dimensional (3D) hollow-porous vanadium pentoxide (V2 O5 ) quasi-microspheres are synthesized by a facile solvothermal method followed by annealing at 450 °C in air. The interconnected hollow-porous networks facilitate the kinetics of lithium-ion diffusion and improve the performance of V2 O5 to achieve a high capacity and remarkable rate capability as a cathode material for lithium batteries.

Graphenal polymers for energy storage

A key to improve the electrochemical performance of energy storage systems (e.g., lithium ion batteries and supercapacitors) is to develop advanced electrode materials. In the last few years, although originating from the unique structure and property of graphene, interest has expanded beyond the originally literally defined graphene into versatile integration of numerous intermediate structures lying between graphene and organic polymer, particularly for the development of new electrode materials for energy storage devices. Notably, diverse designations have shaded common characteristics of the molecular configurations of these newly-emerging materials, severely impeding the design, synthesis, tailoring, functionalization, and control of functional electrode materials in a rational and systematical manner. This concept paper highlights all these intermediate materials, specifically comprising graphene subunits intrinsically interconnected by organic linkers or fractions, following a general concept of graphenal polymers. Combined with recent advances made by our group and others, two representative synthesis approaches (bottom-up and top-down) for graphenal polymers are outlined, as well as the structure-property relationships of these graphenal polymers as energy storage electrode materials are discussed.

A mild route to mesoporous Mo2C-C hybrid nanospheres for high performance lithium-ion batteries

In this work, we have developed a mild route to fabricate typically mesoporous Mo2C-C hybrid nanospheres based on a solvothermal synthesis and reduction-carbonization process. This work opens a low-temperature route to synthesize valuable carbides. The resultant Mo2C-C hybrid, for the first time, is used as an anode material in lithium ion batteries (LIBs). Compared with bulk Mo2C, the Mo2C-C hybrid exhibits much better electrochemical performance. Remarkably, the hybrid electrode can deliver a specific capacity of over 670 mA h g(-1) after 50 cycles at 100 mA g(-1), which is much higher than that of the bulk material (113 mA h g(-1)). Even cycled at a high current density of 1000 mA g(-1), high capacities of around 400-470 mA h g(-1) can still be retained for the Mo2C-C hybrid. It might benefit from the synergistic effect of the nanohybridization, effectively relieving the volume change during the repeated lithium insertion-extraction reactions and maintaining the integrity of the electrical connections. It is expected that the present synthesis strategy for the Mo2C-C hybrid can be extended to other nanostructured carbides with good energy storage performance.

Ultrasmall SnO₂ nanocrystals: hot-bubbling synthesis, encapsulation in carbon layers and applications in high capacity Li-ion storage

Ultrasmall SnO₂ nanocrystals as anode materials for lithium-ion batteries (LIBs) have been synthesized by bubbling an oxidizing gas into hot surfactant solutions containing Sn-oleate complexes. Annealing of the particles in N₂ carbonifies the densely packed surface capping ligands resulting in carbon encapsulated SnO₂ nanoparticles (SnO₂/C). Carbon encapsulation can effectively buffer the volume changes during the lithiation/delithiation process. The assembled SnO₂/C thus deliver extraordinarily high reversible capacity of 908 mA·h·g⁻¹ at 0.5 C as well as excellent cycling performance in the LIBs. This method demonstrates the great potential of SnO₂/C nanoparticles for the design of high power LIBs.

3D interconnected SnO2-coated Cu foam as a high-performance anode for lithium-ion battery applications

A SnO₂-coated Cu foam with 3D interconnected scaffold was fabricated as a self-supporting anode for lithium-ion batteries. The binder- and carbon- free electrode exhibits a high reversible capacity by preserving its structural integrity.

Facile preparation of ordered porous graphene-metal oxide@C binder-free electrodes with high Li storage performance

A facile and general method is reported to prepare ordered porous graphene-based binder-free electrodes on a large scale. This preparation process allows the easy adjustment of the selected components, weight ratio of componets, and the thickness of the electrodes. Such ordered porous electrodes demonstrate superior Li storage properties; for example, graphene-Fe3 O4 @C depicts high capacities of 1123.8 and 505 mAh g(-1) at current densities of 0.5 and 10 A g(-1) , respectively.

Core-shell tin oxide, indium oxide, and indium tin oxide nanoparticles on silicon with tunable dispersion: electrochemical and structural characteristics as a hybrid Li-ion battery anode

Tin oxide (SnO2) is considered a very promising material as a high capacity Li-ion battery anode. Its adoption depends on a solid understanding of factors that affect electrochemical behavior and performance such as size and composition. We demonstrate here, that defined dispersions and structures can improve our understanding of Li-ion battery anode material architecture on alloying and co-intercalation processes of Lithium with Sn from SnO2 on Si. Two different types of well-defined hierarchical Sn@SnO2 core-shell nanoparticle (NP) dispersions were prepared by molecular beam epitaxy (MBE) on silicon, composed of either amorphous or polycrystalline SnO2 shells. In2O3 and Sn doped In2O3 (ITO) NP dispersions are also demonstrated from MBE NP growth. Lithium alloying with the reduced form of the NPs and co-insertion into the silicon substrate showed reversible charge storage. Through correlation of electrochemical and structural characteristics of the anodes, we detail the link between the composition, areal and volumetric densities, and the effect of electrochemical alloying of Lithium with Sn@SnO2 and related NPs on their structure and, importantly, their dispersion on the electrode. The dispersion also dictates the degree of co-insertion into the Si current collector, which can act as a buffer. The compositional and structural engineering of SnO2 and related materials using highly defined MBE growth as model system allows a detailed examination of the influence of material dispersion or nanoarchitecture on the electrochemical performance of active electrodes and materials.

SnO₂-based nanomaterials: synthesis and application in lithium-ion batteries

The development of new electrode materials for lithium-ion batteries (LIBs) has always been a focal area of materials science, as the current technology may not be able to meet the high energy demands for electronic devices with better performance. Among all the metal oxides, tin dioxide (SnO₂) is regarded as a promising candidate to serve as the anode material for LIBs due to its high theoretical capacity. Here, a thorough survey is provided of the synthesis of SnO₂-based nanomaterials with various structures and chemical compositions, and their application as negative electrodes for LIBs. It covers SnO₂ with different morphologies ranging from 1D nanorods/nanowires/nanotubes, to 2D nanosheets, to 3D hollow nanostructures. Nanocomposites consisting of SnO₂ and different carbonaceous supports, e.g., amorphous carbon, carbon nanotubes, graphene, are also investigated. The use of Sn-based nanomaterials as the anode material for LIBs will be briefly discussed as well. The aim of this review is to provide an in-depth and rational understanding such that the electrochemical properties of SnO₂-based anodes can be effectively enhanced by making proper nanostructures with optimized chemical composition. By focusing on SnO₂, the hope is that such concepts and strategies can be extended to other potential metal oxides, such as titanium dioxide or iron oxides, thus shedding some light on the future development of high-performance metal-oxide based negative electrodes for LIBs.

Use of organic precursors and graphenes in the controlled synthesis of carbon-containing nanomaterials for energy storage and conversion

The development of high-performance electrochemical energy storage and conversion devices, including supercapacitors, lithium-ion batteries, and fuel cells, is an important step on the road to alternative energy technologies. Carbon-containing nanomaterials (CCNMs), defined here as pure carbon materials and carbon/metal (oxide, hydroxide) hybrids with structural features on the nanometer scale, show potential application in such devices. Because of their pronounced electrochemical activity, high chemical and thermal stability and low cost, researchers are interested in CCNMs to serve as electrodes in energy-related devices. Various all-carbon materials are candidates for electrochemical energy storage and conversion devices. Furthermore, carbon-based hybrid materials, which consist of a carbon component with metal oxide- or metal hydroxide-based nanostructures, offer the opportunity to combine the attractive properties of these two components and tune the behavior of the resulting materials. As such, the design and synthesis of CCNMs provide an attractive route for the construction of high-performance electrode materials. Studies in these areas have revealed that both the composition and the fabrication protocol employed in preparing CCNMs influence the morphology and microstructure of the resulting material and its electrochemical performance. Consequently, researchers have developed several synthesis strategies, including hard-templated, soft-templated, and template-free synthesis of CCNMs. In this Account, we focus on recent advances in the controlled synthesis of such CCNMs and the potential of the resulting materials for energy storage or conversion applications. The Account is divided into four major categories based on the carbon precursor employed in the synthesis: low molecular weight organic or organometallic molecules, hyperbranched or cross-linked polymers consisting of aromatic subunits, self-assembling discotic molecules, and graphenes. In each case, we highlight representative examples of CCNMs with both new nanostructures and electrochemical performance suitable for energy storage or conversion applications. In addition, this Account provides an overall perspective on the current state of efforts aimed at the controlled synthesis of CCNMs and identifies some of the remaining challenges.