One-pot synthesis of tin-embedded carbon/silica nanocomposites for anode materials in lithium-ion batteries

Synthesis of self-renewing Fe(0)-dispersed ordered mesoporous carbon for electrocatalytic reduction of nitrates to nitrogen

In electrocatalytic reduction of nitrates to nitrogen, key issues are electrode activity, sustainable materials, preparation methods and cost. Herein, lignin, Fe³⁺ ion, and non-ionic surfactant were combined with evaporation-induced self-assembly (EISA) to prepare zero-valent Fe-dispersed ordered mesoporous carbon (OMC) electrode materials denoted as Fe#OMC. The method developed for preparing Fe-coordinated OMC material avoids the use of toxic phenols, aldehyde reagents and metal doping compounds. When synthesized Fe#OMC samples were applied as electrode materials for the electrocatalytic reduction of nitrate in aqueous solutions, maximum nitrate nitrogen removal was as high as 5373 mg N·g^-1 Fe from aqueous solutions containing 400 mg·L^-1 NO₃^--N, while nitrogen selectivity was close to 100%, exceeding catalytic performance of comparable materials. Active hydrogen produced by electrolysis of water during the reaction re-reduced Fe ions formed in the OMC material and stabilized Fe#OMC electrode performance and recycle. The Fe#OMC electrode is self-renewing with respect to its Fe zero-valent state, is simple to prepare from sustainable materials and is effective for electrocatalytic reduction of nitrate or nitrogen-containing compounds in water.

Accurately Localizing Multiple Nanoparticles in a Multishelled Matrix Through Shell-to-Core Evolution for Maximizing Energy-Storage Capability

Robust and fast lithium energy storage with a high energy density is highly desired to accelerate the market adoption of electric vehicles. To realize such a goal requires the development of electrode materials with a high capacity, however, such electrode materials suffer from huge volume expansion and induced short cycling life. Here, using tin (Sn) as an example, an ideal structure is designed to effectively solve these problems by separately localizing multiple Sn nanoparticles in a nitrogen-doped carbon hollow multishelled structure with duplicated layers for carbon shell (Sn NPs@N_x C HoMS-DL). The fabricated composite can promote ion and electron diffusion owing to the conductive network formed by connected multiple shells and cores, effectively buffer the volume expansion, and maintain a stable electrode-electrolyte interface. Despite the challenging fabrication, such a structure is realized through an innovative and facile synthesis strategy of "in situ evolution of shell to core", which is applicable for diverse low-melting-point materials. As expected, such a structure enables the high-capacity electrode material to realize nearly its theoretical lithium-storage capability: the developed Sn NPs@N_x C HoMS-DL electrode maintains 96% of its theoretical capacity after 2000 cycles at 2C.

Binder-Free, Flexible, and Self-Standing Non-Woven Fabric Anodes Based on Graphene/Si Hybrid Fibers for High-Performance Li-Ion Batteries

High-capacity silicon (Si) is recognized as a potential anode material for high-performance lithium-ion batteries (LIBs). Unfortunately, large volume expansion during discharge/charge processes hinders its areal capacity. In this work, we design a flexible graphene-fiber-fabric (GFF)-based three-dimensional conductive network to form a binder-free and self-standing Si anode for high-performance LIBs. The Si particles are strongly wrapped in graphene fibers. The substantial void spaces caused by the wrinkled graphene in fibers enable effective accommodation of the volume change of Si during lithiation/delithiation processes. The GFF/Si-37.5% electrode exhibits an excellent cyclability with a specific capacity of 920 mA h g^-1 at a current density of 0.4 mA cm^-2 after 100 cycles. Furthermore, the GFF/Si-29.1% electrode exhibits an excellent reversible capacity of 580 mA h g^-1 at a current density of 0.4 mA cm^-2 after 400 cycles. The capacity retention of the GFF/Si-29.1% electrode is up to 96.5%. More importantly, the GFF/Si-37.5% electrode with a mass loading of 13.75 mg cm^-2 achieves a high areal capacity of 14.3 mA h cm^-2, which outperforms the reported self-standing Si anode. This work provides opportunities for realizing a binder-free, flexible, and self-standing Si anode for high-energy LIBs.

Graphene-Based Two-Dimensional Mesoporous Materials: Synthesis and Electrochemical Energy Storage Applications

Graphene (G)-based two dimensional (2D) mesoporous materials combine the advantages of G, ultrathin 2D morphology, and mesoporous structures, greatly contributing to the improvement of power and energy densities of energy storage devices. Despite considerable research progress made in the past decade, a complete overview of G-based 2D mesoporous materials has not yet been provided. In this review, we summarize the synthesis strategies for G-based 2D mesoporous materials and their applications in supercapacitors (SCs) and lithium-ion batteries (LIBs). The general aspect of synthesis procedures and underlying mechanisms are discussed in detail. The structural and compositional advantages of G-based 2D mesoporous materials as electrodes for SCs and LIBs are highlighted. We provide our perspective on the opportunities and challenges for development of G-based 2D mesoporous materials. Therefore, we believe that this review will offer fruitful guidance for fabricating G-based 2D mesoporous materials as well as the other types of 2D heterostructures for electrochemical energy storage applications.

Self-assembly of block copolymers towards mesoporous materials for energy storage and conversion systems

This paper reviews the progress in the field of block copolymer-templated mesoporous materials, including synthetic methods, morphological and pore size control and their potential applications in energy storage and conversion devices.

High performance lithium battery anode materials by coating SiO2 nanowire arrays with PEO

SiO₂@PEO nanowire arrays were prepared by a simple method and exhibited excellent electrochemical performance as LIB anode materials.

Generalized Access to Mesoporous Inorganic Particles and Hollow Spheres from Multicomponent Polymer Blends

Mesoporous inorganic particles and hollow spheres are of increasing interest for a broad range of applications, but synthesis approaches are typically material specific, complex, or lack control over desired structures. Here it is reported how combining mesoscale block copolymer (BCP) directed inorganic materials self-assembly and macroscale spinodal decomposition can be employed in multicomponent BCP/hydrophilic inorganic precursor blends with homopolymers to prepare mesoporous inorganic particles with controlled meso- and macrostructures. The homogeneous multicomponent blend solution undergoes dual phase separation upon solvent evaporation. Microphase-separated (BCP/inorganic precursor)-domains are confined within the macrophase-separated majority homopolymer matrix, being self-organized toward particle shapes that minimize the total interfacial area/energy. The pore orientation and particle shape (solid spheres, oblate ellipsoids, hollow spheres) are tailored by changing the kind of homopolymer matrix and associated enthalpic interactions. Furthermore, the sizes of particle and hollow inner cavity are tailored by changing the relative amount of homopolymer matrix and the rates of solvent evaporation. Pyrolysis yields discrete mesoporous inorganic particles and hollow spheres. The present approach enables a high degree of control over pore structure, orientation, and size (15-44 nm), particle shape, particle size (0.6-3 µm), inner cavity size (120-700 nm), and chemical composition (e.g., aluminosilicates, carbon, and metal oxides).

Self-Relaxant Superelastic Matrix Derived from C60 Incorporated Sn Nanoparticles for Ultra-High-Performance Li-Ion Batteries

Homogeneously dispersed Sn nanoparticles approximately ⩽10 nm in a polymerized C₆₀ (PC₆₀) matrix, employed as the anode of a Li-ion battery, are prepared using plasma-assisted thermal evaporation coupled by chemical vapor deposition. The self-relaxant superelastic characteristics of the PC₆₀ possess the ability to absorb the stress-strain generated by the Sn nanoparticles and can thus alleviate the problem of their extreme volume changes. Meanwhile, well-dispersed dot-like Sn nanoparticles, which are surrounded by a thin SnO₂ layer, have suitable interparticle spacing and multilayer structures for alleviating the aggregation of Sn nanoparticles during repeated cycles. The Ohmic characteristic and the built-in electric field formed in the interparticle junction play important roles in enhancing the diffusion and transport rate of Li ions. SPC-50, a Sn-PC₆₀ anode consisting of 50 wt % Sn and 50 wt % PC₆₀, as confirmed by energy-dispersive X-ray spectroscopy analysis, exhibited the highest electrochemical performance. The resulting SPC-50 anode, in a half-cell configuration, exhibited an excellent capacity retention of 97.18%, even after 5000 cycles at a current density of 1000 mA g^-1 with a discharge capacity of 834.25 mAh g^-1. In addition, the rate-capability performance of this SPC-50 half-cell exhibited a discharge capacity of 544.33 mAh g^-1 at a high current density of 10 000 mA g^-1, even after the current density was increased 100-fold. Moreover, a very high discharge capacity of 1040.09 mAh g^-1 was achieved with a capacity retention of 98.67% after 50 cycles at a current density of 100 mA g^-1. Futhermore, a SPC-50 full-cell containing the LiCoO₂ cathode exhibited a discharge capacity of 801.04 mAh g^-1 and an areal capacity of 1.57 mAh cm^-2 with a capacity retention of 95.27% after 350 cycles at a current density of 1000 mA g^-1.

Oxidized Co-Sn nanoparticles as long-lasting anode materials for lithium-ion batteries

Herein, we present the synthesis and systematic comparison of Sn- and Co-Sn-based nanoparticles (NPs) as anode materials for lithium-ion batteries. These nanomaterials were produced via inexpensive routes combining wet chemical synthesis and dry mechanochemical methods (ball milling). We demonstrate that oxidized, nearly amorphous CoSn₂O_x NPs, in contrast to highly crystalline Sn and CoSn₂ NPs, exhibit high cycling stability over 1500 cycles, retaining a capacity of 525 mA h g^-1 (92% of the initial capacity) at a high current density of 1982 mA g^-1. Moreover, when cycled in full-cell configuration with LiCoO₂ as the cathode, such CoSn₂O_x NPs deliver an average anodic capacity of 576 mA h g^-1 over 100 cycles at a current of 500 mA g^-1, with an average discharge voltage of 3.14 V.

High-capacity and long-life lithium storage boosted by pseudocapacitance in three-dimensional MnO-Cu-CNT/graphene anodes

Boosting the lifespan of MnO-based materials for future lithium ion batteries is one of the primary challenges due to the intrinsic low ionic conductivity and volume expansion during the conversion process. Herein, superior lithium storage in a new quaternary MnO-Cu-CNT/graphene composite has been demonstrated, which is boosted by pseudocapacitance benefitting from the three-dimensional CNT/graphene and nanosized Cu additives. Such architecture offers highly interpenetrated porous conductive networks in intimate contact with MnO-Cu grains and abundant stress buffer space for effective charge transport upon cycling. The ternary MnO-Cu-graphene electrode contributes an ever-increasing reversible capacity of 938.3 mA h g^-1 after 800 cycles at 0.8 A g^-1. In particular, the quaternary MnO-Cu-CNT/graphene electrode demonstrates a high specific capacity of 1334 mA h g^-1 at 0.8 A g^-1 after 800 cycles and long lifetimes of more than 3500 cycles at 5 A g^-1 with a capacity of 557.9 mA h g^-1 and close-to-100% Coulombic efficiency. The boosted pseudocapacitive lithium storage together with the simple material fabrication method in a MnO-Cu-CNT/graphene hybrid could pave the way for the development of high-capacity and long-life energy storage devices.

Multiscale Phase Separations for Hierarchically Ordered Macro/Mesostructured Metal Oxides

Porous architectures play an important role in various applications of inorganic materials. Several attempts to develop mesoporous materials with controlled macrostructures have been reported, but they usually require complicated multiple-step procedures, which limits their versatility and suitability for mass production. Here, a simple approach for controlling the macrostructures of mesoporous materials, without templates for the macropores, is reported. The controlled solvent evaporation induces both macrophase separation via spinodal decomposition and mesophase separation via block copolymer self-assembly, leading to the formation of hierarchically porous metal oxides with periodic macro/mesostructures. In addition, using this method, macrostructures of mesoporous metal oxides are controlled into spheres and mesoporous powders containing isolated macropores. Nanocomputed tomography, focused ion beam milling, and electron microscopy confirm well-defined macrostructures containing mesopores. Among the various porous structures, hierarchically macro/mesoporous metal oxide is employed as an anode material in lithium-ion batteries. The present approach could provide a broad and easily accessible platform for the manufacturing of mesoporous inorganic materials with different macrostructures.

CTAB-assisted growth of self-supported Zn2GeO4 nanosheet network on a conductive foam as a binder-free electrode for long-life lithium-ion batteries

The Ge-based compounds show great potential as replacements for traditional graphite anode in lithium-ion batteries (LIBs). However, large volume changes and low conductivity of such materials result in a poor electrochemical cycling and rate performance. Herein, we fabricate a self-supported and three-dimensional (3D) sponge-like structure of interlinked Zn₂GeO₄ ultrathin nanosheets anchored vertically on a nickel foam (ZGO NSs@NF) via a simple hydrothermal process assisted by cetyltrimethyl ammonium bromide (CTAB). Such robust self-supported hybrid structures greatly improve the structural tolerance of the active materials and accommodate the volume variation that occurs during repeated electrochemical cycling. As expected, the self-supported ZGO NSs@NF composites demonstrate an excellent lithium storage with a high discharge capacity, a long cycling life, and a good rate capability when used as binder-free anodes for LIBs. A high reversible discharge capacity of 794 mA h g^-1 is maintained after 500 cycles at 200 mA g^-1, corresponding to 81% capacity retention of the second cycle. Further evaluation at a higher current density (2 A g^-1) also delivers a reversible discharge capacity (537 mA h g^-1) for this binder-free anode. This novel 3D structure of the self-supported ultrathin nanosheets on a conductive substrate, with its volume buffer effect and good interfacial contacts, can stimulate the progress of other energy-efficient technologies.

Bimetal-Organic-Framework Derivation of Ball-Cactus-Like Ni-Sn-P@C-CNT as Long-Cycle Anode for Lithium Ion Battery

Metal phosphides are a new class of potential high-capacity anodes for lithium ion batteries, but their short cycle life is the critical problem to hinder its practical application. A unique ball-cactus-like microsphere of carbon coated NiP₂ /Ni₃ Sn₄ with deep-rooted carbon nanotubes (Ni-Sn-P@C-CNT) is demonstrated in this work to solve this problem. Bimetal-organic-frameworks (BMOFs, Ni-Sn-BTC, BTC refers to 1,3,5-benzenetricarboxylic acid) are formed by a two-step uniform microwave-assisted irradiation approach and used as the precursor to grow Ni-Sn@C-CNT, Ni-Sn-P@C-CNT, yolk-shell Ni-Sn@C, and Ni-Sn-P@C. The uniform carbon overlayer is formed by the decomposition of organic ligands from MOFs and small CNTs are deeply rooted in Ni-Sn-P@C microsphere due to the in situ catalysis effect of Ni-Sn. Among these potential anode materials, the Ni-Sn-P@C-CNT is found to be a promising anode with best electrochemical properties. It exhibits a large reversible capacity of 704 mA h g^-1 after 200 cycles at 100 mA g^-1 and excellent high-rate cycling performance (a stable capacity of 504 mA h g^-1 retained after 800 cycles at 1 A g^-1 ). These good electrochemical properties are mainly ascribed to the unique 3D mesoporous structure design along with dual active components showing synergistic electrochemical activity within different voltage windows.

New Insight into the Synthesis of Large-Pore Ordered Mesoporous Materials

Ordered mesoporous materials (OMMs) have received increasing interest due to their uniform pore size, high surface area, various compositions and wide applications in energy conversion and storage, biomedicine and environmental remediation, etc. The soft templating synthesis using surfactants or amphiphilic block copolymers is the most efficient method to produce OMMs with tailorable pore structure and surface property. However, due to the limited choice of commercially available soft templates, the common OMMs usually show small pore size and amorphous (or semicrystalline) frameworks. Tailor-made amphiphilic block copolymers with controllable molecular weights and compositions have recently emerged as alternative soft templates for synthesis of new OMMs with many unique features including adjustable mesostructures and framework compositions, ultralarge pores, thick pore walls, high thermal stability and crystalline frameworks. In this Perspective, recent progresses and some new insights into the coassembly process about the synthesis of OMMs based on these tailor-made copolymers as templates are summarized, and typical newly developed synthesis methods and strategies are discussed in depth, including solvent evaporation induced aggregation, ligand-assisted coassembly, solvent evaporation induced micelle fusion-aggregation assembly, homopolymer assisted pore expanding and carbon-supported crystallization strategy. Then, the applications of the obtained large-pore OMMs in catalysis, sensor, energy conversion and storage, and biomedicine by loading large-size guest molecules (e.g., protein and RNA), precious metal nanoparticles and quantum dots, are discussed. At last, the outlook on the prospects and challenges of future research about the synthesis of large-pore OMMs by using tailor-made amphiphilic block copolymers are included.

Atomic layer deposition of ZnO on carbon black as nanostructured anode materials for high-performance lithium-ion batteries

Although zinc oxide (ZnO), a low-cost and naturally abundant material, has a high theoretical specific capacity of 987 mA h g^-1 for hosting lithium ions, its application as an anode material has been hindered by its rapid capacity fading, mainly due to a large volume change (around 228%) upon repeated charge-discharge cycles. Herein, using carbon black (CB) powder as a support, ZnO-carbon black (denoted as ZnO-CB) nanocomposites were successfully fabricated using the atomic layer deposition (ALD) method. This method was able to produce strong interfacial molecular bindings between ZnO nanoclusters and the carbon surface that provide stable and robust electrical contact during lithiation and delithiation processes, as well as ZnO nanoclusters rich in oxygen vacancies (OVs) for faster Li-ion transport. Overall, the nanocomposites were able to deliver a high discharge specific capacity of 2096 mA h g^-1_ZnO at 100 mA g^-1 and stable cyclic stability with a specific capacity of 1026 mA h g^-1_ZnO maintained after 500 cycles. The composites also have excellent rate capability, and a reversible capacity at a high 1080 mA h g^-1_ZnO at 2000 mA g^-1. The facile but unique synthesis method demonstrated in this work for producing nanostructures rich in OVs and nanocomposites with strong coupling via interfacial molecular bindings could be extended to the synthesis of other oxide based anode materials and therefore could have general significance for developing high energy density lithium ion batteries.

Simple synthesis of multiple length-scale structured Nb2O5 with functional macrodomain-integrated mesoporous frameworks

Multiple length-scale structured Nb₂O₅ was synthesized by the interplay of macro- and microphase separation and macro-/mesostructures exhibit light-scattering capability and high surface areas.

A novel tin hybrid nano-composite with double nets of carbon matrixes as a stable anode in lithium ion batteries

A novel hybrid anode consisting of tin encapsulated by double nets is presented, which is demonstrated via in situ transmission electron microscopy.

Free radical and RAFT polymerization of vinyl esters in metal–organic-frameworks

In here, the reversible deactivation radical polymerization of vinyl esters inside metal–organic frameworks is presented for the first time.

Ammonium Fluoride Mediated Synthesis of Anhydrous Metal Fluoride-Mesoporous Carbon Nanocomposites for High-Performance Lithium Ion Battery Cathodes

Metal fluorides (MF_x) are one of the most attractive cathode candidates for Li ion batteries (LIBs) due to their high conversion potentials with large capacities. However, only a limited number of synthetic methods, generally involving highly toxic or inaccessible reagents, currently exist, which has made it difficult to produce well-designed nanostructures suitable for cathodes; consequently, harnessing their potential cathodic properties has been a challenge. Herein, we report a new bottom-up synthetic method utilizing ammonium fluoride (NH₄F) for the preparation of anhydrous MF_x (CuF₂, FeF₃, and CoF₂)/mesoporous carbon (MSU-F-C) nanocomposites, whereby a series of metal precursor nanoparticles preconfined in mesoporous carbon were readily converted to anhydrous MF_x through simple heat treatment with NH₄F under solventless conditions. We demonstrate the versatility, lower toxicity, and efficiency of this synthetic method and, using XRD analysis, propose a mechanism for the reaction. All MF_x/MSU-F-C prepared in this study exhibited superior electrochemical performances, through conversion reactions, as the cathode for LIBs. In particular, FeF₃/MSU-F-C maintained a capacity of 650 mAh g^-1_FeF3 across 50 cycles, which is ∼90% of its initial capacity. We expect that this facile synthesis method will trigger further research into the development of various nanostructured MF_x for use in energy storage and other applications.

Self-supported Zn3P2 nanowire arrays grafted on carbon fabrics as an advanced integrated anode for flexible lithium ion batteries

We, for the first time, successfully grafted well-aligned binary lithium-reactive zinc phosphide (Zn3P2) nanowire arrays on carbon fabric cloth by a facile CVD method. When applied as a novel self-supported binder-free anode for lithium ion batteries (LIBs), the hierarchical three-dimensional (3D) integrated anode shows excellent electrochemical performances: a highly reversible initial lithium storage capacity of ca. 1200 mA h g(-1) with a coulombic efficiency of up to 88%, a long lifespan of over 200 cycles without obvious decay, and a high rate capability of ca. 400 mA h g(-1) capacity retention at an ultrahigh rate of 15 A g(-1). More interestingly, a flexible LIB full cell is assembled based on the as-synthesized integrated anode and the commercial LiFePO4 cathode, and shows striking lithium storage performances very close to the half cells: a large reversible capacity over 1000 mA h g(-1), a long cycle life of over 200 cycles without obvious decay, and an ultrahigh rate performance of ca. 300 mA h g(-1) even at 20 A g(-1). Considering the excellent lithium storage performances of coin-type half cells as well as flexible full cells, the as-prepared carbon cloth grafted well-aligned Zn3P2 nanowire arrays would be a promising integrated anode for flexible LIB full cell devices.

A mini review of designed mesoporous materials for energy-storage applications: from electric double-layer capacitors to hybrid supercapacitors

In recent years, porous materials have attracted significant attention in various research fields because of their structural merits. In particular, well-designed mesoporous structures with two- or three-dimensionally interconnected pores have been recognized as electrode materials of particular interest for achieving high-performance electrochemical capacitors (ECs). In this mini review, recent progress in the design of mesoporous electrode materials for ECs, from electric double-layer capacitors (EDLCs) and pseudocapacitors (PCs) to hybrid supercapacitors (HSCs), and research challenges for the development of new mesoporous electrode materials has been discussed.

Synthesis of TiO₂-loaded Co0.85Se thin films with heterostructure and their enhanced catalytic activity for p-nitrophenol reduction and hydrazine hydrate decomposition

P-nitrophenol (4-NP) and hydrazine hydrate are considered to be highly toxic pollutants in wastewater, and it is of great importance to remove them. Herein, TiO2-loaded Co0.85Se thin films with heterostructure were successfully synthesized by a hydrothermal route. The as-synthesized samples were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, transmission electron microscopy and selective-area electron diffraction. The results demonstrate that TiO2 nanoparticles with a size of about 10 nm are easily loaded on the surface of graphene-like Co0.85Se nanofilms, and the NH3 · H2O plays an important role in the generation and crystallization of TiO2 nanoparticles. Brunauer-Emmett-Teller measurement shows that the obtained nanocomposites have a larger specific surface area (199.3 m(2) g(-1)) than that of Co0.85Se nanofilms (55.17 m(2) g(-1)) and TiO2 nanoparticles (19.49 m(2) g(-1)). The catalytic tests indicate Co0.85Se-TiO2 nanofilms have the highest activity for 4-NP reduction and hydrazine hydrate decomposition within 10 min and 8 min, respectively, compared with the corresponding precursor Co0.85Se nanofilms and TiO2 nanoparticles. The enhanced catalytic performance can be attributed to the larger specific surface area and higher rate of interfacial charge transfer in the heterojunction than that of the single components. In addition, recycling tests show that the as-synthesized sample presents stable conversion efficiency for 4-NP reduction.

Nitrogen-Doped Carbon-Encapsulated SnO2@Sn Nanoparticles Uniformly Grafted on Three-Dimensional Graphene-like Networks as Anode for High-Performance Lithium-Ion Batteries

A peculiar nanostructure consisting of nitrogen-doped, carbon-encapsulated (N-C) SnO2@Sn nanoparticles grafted on three-dimensional (3D) graphene-like networks (designated as N-C@SnO2@Sn/3D-GNs) has been fabricated via a low-cost and scalable method, namely an in situ hydrolysis of Sn salts and immobilization of SnO2 nanoparticles on the surface of 3D-GNs, followed by an in situ polymerization of dopamine on the surface of the SnO2/3D-GNs, and finally a carbonization. In the composites, three-layer core-shell N-C@SnO2@Sn nanoparticles were uniformly grafted onto the surfaces of 3D-GNs, which promotes highly efficient insertion/extraction of Li(+). In addition, the outermost N-C layer with graphene-like structure of the N-C@SnO2@Sn nanoparticles can effectively buffer the large volume changes, enhance electronic conductivity, and prevent SnO2/Sn aggregation and pulverization during discharge/charge. The middle SnO2 layer can be changed into active Sn and nano-Li2O during discharge, as described by SnO2 + Li(+) → Sn + Li2O, whereas the thus-formed nano-Li2O can provide a facile environment for the alloying process and facilitate good cycling behavior, so as to further improve the cycling performance of the composite. The inner Sn layer with large theoretical capacity can guarantee high lithium storage in the composite. The 3D-GNs, with high electrical conductivity (1.50 × 10(3) S m(-1)), large surface area (1143 m(2) g(-1)), and high mechanical flexibility, tightly pin the core-shell structure of the N-C@SnO2@Sn nanoparticles and thus lead to remarkably enhanced electrical conductivity and structural integrity of the overall electrode. Consequently, this novel hybrid anode exhibits highly stable capacity of up to 901 mAh g(-1), with ∼89.3% capacity retention after 200 cycles at 0.1 A g(-1) and superior high rate performance, as well as a long lifetime of 500 cycles with 84.0% retention at 1.0 A g(-1). Importantly, this unique hybrid design is expected to be extended to other alloy-type anode materials such as silicon, germanium, etc.

Sn/carbon nanofibers fabricated by electrospinning with enhanced lithium storage capabilities

Well dispersed Sn nanoparticles/carbon nanofibers with enhanced lithium storage capabilities were fabricated by electrospinning.

Mesoporous SnO2–SiO2 and Sn–silica–carbon nanocomposites by novel non-hydrolytic templated sol–gel synthesis

A novel non-hydrolytic sol–gel (NHSG) synthesis of mesoporous tin silicate xerogels is presented.

Direct access to aggregation-free and small intermetallic nanoparticles in ordered, large-pore mesoporous carbon for an electrocatalyst

Small-sized intermetallic catalysts are synthesized by block copolymer-assisted evaporation-induced self-assembly, incorporating an agent that interacts strongly with metal.

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.

Structural Effect on Electrochemical Performance of Ordered Porous Carbon Electrodes for Na-Ion Batteries

Ordered meso- or macro-porous carbons (OMCs) were applied as anodes in Na ion battery (NIB) systems. Three different block copolymers (BCPs) enabled us to control the pore sizes (6, 33, and 60 nm) while maintaining the same 2-D hexagonal structure. To exclude other effects, the factors including precursors, particle sizes, and degrees of graphitization were controlled. The structures of OMCs were characterized by nitrogen physisorption, Raman spectroscopy, X-ray analyses (XRD and SAXS), and microscopies (TEM and SEM). With a galvanostatic charge/discharge, we confirmed that OMC electrode with medium pore size (OMC-33) exhibited a higher reversible capacity of 134 mA h g(-1) (at 20th cycle) and faster rate capability (61% retention, current densities from 50 to 5000 mA g(-1)) than those of OMC-6, and OMC-60 electrodes. The high performance of OMC-33 is attributed to the combined effects of pore size and wall thickness which was supported by charge/discharge and electrochemical impedance spectroscopy (EIS) analyses.

Mesoporous Ge/GeO2/Carbon Lithium-Ion Battery Anodes with High Capacity and High Reversibility

We report mesoporous composite materials (m-GeO2, m-GeO2/C, and m-Ge-GeO2/C) with large pore size which are synthesized by a simple block copolymer directed self-assembly. m-Ge/GeO2/C shows greatly enhanced Coulombic efficiency, high reversible capacity (1631 mA h g(-1)), and stable cycle life compared with the other mesoporous and bulk GeO2 electrodes. m-Ge/GeO2/C exhibits one of the highest areal capacities (1.65 mA h cm(-2)) among previously reported Ge- and GeO2-based anodes. The superior electrochemical performance in m-Ge/GeO2/C arises from the highly improved kinetics of conversion reaction due to the synergistic effects of the mesoporous structures and the conductive carbon and metallic Ge.

High-performance and ultra-stable lithium-ion batteries based on MOF-derived ZnO@ZnO quantum dots/C core-shell nanorod arrays on a carbon cloth anode

MOF-derived ZnO@ZnO Quantum Dots/C core-shell nanorod arrays grown on flexible carbon cloth are successfully fabricated as a binder-free anode for Li-ion storage. In combination with the advantages from the ZnO/C core-shell architecture and the 3D nanorod arrays, this material satisfies both efficient ion and fast electron transport, and thus shows superior rate capability and excellent cycling stability.

A plum-pudding like mesoporous SiO2/flake graphite nanocomposite with superior rate performance for LIB anode materials

A novel kind of plum-pudding like mesoporous SiO₂ nanospheres (MSNs) and flake graphite (FG) nanocomposite (pp-MSNs/FG) was designed and fabricated via a facile and cost-effective hydrothermal method.