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Nowadays, Lithium-ion batteries (LIBs) are prevalently applied in numerous areas, leading to increasing demand of innovative electrodes with high specific capacities. An advanced CuGeO 3 /reduced graphene oxide (rGO) structure is designed and fabricated as the anode material taking the advantage of considerable capacity offered by CuGeO 3 and stable framework constructed by rGO. The as-prepared CuGeO 3 with 30 wt% GO addition exhibits the best electrochemical performance. Specifically, a reversible charge capacity of 909 mAh·g−1 with high coulombic efficiency of 91.49% at the current density of 100 mA g−1 after 200 cycles is demonstrated, and the rate capacity retains 747.6 mAh·g−1 with 91.59% capacity retention. These results indicate that the CuGeO 3 /rGO composite holds great potential in next-generation LIBs. [ABSTRACT FROM AUTHOR]

• Silicon nanoparticles are encapsulated in defect-repaired RGO cages. • The DRGO possesses satisfy graphitization degree with enhanced electrochemical properties. • DRGO cages can effectively restrict the volumetric expansion of silicon cores. • The composite anode occupies outstanding ionic and electronic conductivity. Combining nanoscale silicon with reduced graphene oxide (RGO) is a transformative approach to assembling high capacity silicon-based anodes for lithium-ion batteries (LIBs). However, preparation of RGO via conventional reduction methods always causes abundant structural defects. The crystalline structure and electronic conductivity of the resultant RGO are seriously damaged. Herein defect-repaired RGO (DRGO) building blocks to support silicon nanoparticles (SiNPs) are prepared, showing enhanced reversible capacity and cyclic performance. Specifically, RGO is engineered to produce a cage-shaped shell, enwrapping SiNPs with reserved interspace. Glucose is used to repair the defects in the graphene oxide (GO) to generate lower-defect RGO. The as-prepared SiNPs embedded in defect-repaired RGO cages (Si@DRGOC) deliver the gravimetric capacity of 2678.4 mA h g−1 at 100 mA g−1 with high coulombic efficiency over 98% as an anode for LIBs. The Si@DRGOC electrode also delivers reasonable rate capacity of 1284.5 mA h g−1 at 2 A g−1, and 2002.7 mA h g−1 as the current density cycling back to 100 mA g−1. This well-engineered structure may provide a promising strategy for fabrication of high-performance LIBs anode materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Silicon is considered as a promising anode candidate for the new generation of lithium-ion batteries by virtue of its extensive sources and ultrahigh theoretical specific capacity (4200 mA h g−1). The inevitable volume change during the lithiation process will lead to a series of troubles, which has become a major obstacle to the large-scale application of silicon-based electrodes. Herein, silicon microspheres with the ordered mesoporous structure are synthesized through magnesiothermic reduction, which allows void for volume expansion to prevent electrode material from pulverizing. Subsequently, the silicon microspheres are packaged with a polydopamine driven nitrogen-doped carbon layer, which is helpful to maintain the structural stability of electrode materials and enhance the electronic conductivity. The resulting OM-Si@C composite material exhibits remarkable lithium storage properties, which behaves a superior reversible specific capacity of 1751.7 mA h g−1 at 0.1 A g−1 after 100 cycles. Furthermore, it also shows excellent rate performance (1183.9 mA h g−1 at 2 A g−1) and long cycle stability. Image 1 • OM-Si@C was prepared by magnesium thermal reduction and carbonization. • The pores in OM-Si@C act as a buffer for the volume expansion of silicon. • The nitrogen-doped carbon coating of OM-Si@C can maintain the structural integrity. [ABSTRACT FROM AUTHOR]

A hollow tremella-like graphene sphere/tin dioxide (HTGS/SnO 2) composite was successfully prepared by simple emulsification and impregnation followed by calcination. In this material, tin dioxide adheres to the folds on the surface of the hollow tremella-like graphene spheres. Hollow tremella-like graphene spheres as the matrix of SnO 2 not only provide a space of volumetric expansion for the tin oxide particles, relieve the internal stress of the tin dioxide, but also effectively avoid aggregation of the tin dioxide and increase the electrical conductivity. As an anode electrode material for batteries, the initial discharge/charge capacities of HTGS/SnO 2 are 1762.4 mAh g-1 and 1169.4 mAh g-1, and the Coulomb efficiency is 96.9%. After 50 cycles, capacity remains 80.4% of reversible capacity. The excellent electrochemical stability is attributed to the extraordinary structure of HTGS/SnO 2. The hollow structure of graphene sphere allows simultaneous insertion of lithium ions from the inner and outer surfaces. Meanwhile, the tin dioxide particles are uniformly dispersed by the wrinkles on the surface of the graphene, thereby enlarging the space for the volume expansion of tin dioxide in order to avoid contact with the electrolyte. [ABSTRACT FROM AUTHOR]

Silicon is regarded as the best choice for the new emergence of lithium-ion battery anode materials owing to its high theoretical capacity and safety, but it also faces great challenges in practical applications, namely structural instability, solid electrolyte interphase film rupture and capacity attenuation caused by volume expansion. Here we report the graphene caging Si nanoparticles anchored on graphene sheets by simple coating and calcination. The interspace between the silicon nanoparticles and the graphene cage affords volume expansion sufficient space. The graphene affords two parts in this material simultaneously, one of which is forming a flexible shell of silicon nanoparticles that can relieve internal stress and improve the adaptability to the expansion of silicon in different directions, the second is building an interlinked network matrix to increase conductivity. Nano‑silicon is under the dual protection of graphene cage and graphene sheets interlinked network, this interesting structure also significantly enhances the electrochemical performance of the silicon nanoparticles. The prepared electrode material exhibits excellent cycle performance with an excellent capacity of 1616.1 mAh g−1 after 100 cycles at a high current density of 1 A g−1. Schematic illustration of the synthesis procedure and the electrochemical performance for SiNP@graphene cage/GNS. Unlabelled Image • Graphene caging Si nanoparticles anchored on graphene sheets were prepared by simple coating and calcination. • The graphene affords two parts in this material simultaneously. • Nano-silicon is under the dual protection of graphene cage and graphene sheets interlinked network. [ABSTRACT FROM AUTHOR]

Highly porous MnO/C@rGO nanocomposites have been successfully prepared via a facile and scalable strategy. Firstly, the Mn-BDC was grown in situ on the graphene oxide containing a large number of functional groups, which acted as not only efficient nucleation sites but also structure-directing templates. Then Mn-BDC@GO could be directly carbonized in an inert atmosphere to obtain highly porous MnO/C@rGO nanocomposites. The addition of graphene improved the electronic conductivity, increased the specific surface area, and its two-dimensional structure enhanced the diffusion rate of lithium ions. The as-fabricated MnO/C@rGO nanocomposites exhibited remarkable reversible specific capacity and excellent cycle stability which maintained a reversible discharge capacity of 1536.4 mA h g−1 after 100 cycles at 100 mA g−1. And more impressively, a discharge capacity of 909.1 mA h g−1 could be retained at a current density of 1 A g−1 after 500 cycles, making it a high-performance anode for lithium ion battery. Moreover, high-capacity, long-cycle, and high-rate performance nanocomposites could be prepared as anode material for lithium-ion batteries through this facile, environmentally friendly, cost-effective method. Image 1 • MnO/C@rGO nanocomposites were prepared by calcining Mn-BDC/rGO precursors. • MnO/C@rGO nanocomposites have a unique porous structure. • The addition of rGO improves the electronic conductivity and the structural stability. • MnO/C@rGO nanocomposites exhibited superior electrochemical performances. [ABSTRACT FROM AUTHOR]

Silicon materials have received widespread attention due to their inherent high theoretical specific capacity. However, large volumetric expansion and poor electrical conductivity hinder the large-scale application of silicon materials. To address these issues, we synthesize mesoporous silicon nanocubes coated by nitrogen-doped carbon shell (MSC@C) and wrapped by graphene (MSC@rGO) respectively. The ordered mesoporous silica nanocubes are obtained via a hydrolysis reaction of Tetraethyl Orthosilicate (TEOS) and further reduced by a magnesiothermic reduction to prepare mesoporous silicon nanocubes (MSC). The porous structure of MSC not only speeds up the transfer of ions and electrons, but also buffers the internal stress triggered by the volume expansion of the electrode material. Moreover, in addition to providing additional lithium storage sites and high conductivity, the graphene or nitrogen-doped carbon shell also effectively prevents aggregation and cracking of the mesoporous silicon, greatly promoting the stability of the entire electrode structure. Therefore, the electrochemical properties of composite materials are significantly enhanced by the combination of the mesoporous structure and the nitrogen-doped carbon shell or graphene. MSC@C can deliver the initial discharge specific capacity of 2852.7 mAh·g−1 and the initial Coulombic efficiency (CE) of 83.74%. After 100 cycles, the MSC@C and MSC@rGO composite materials exhibit reversible specific capacities of 1070.5 mAh·g−1 and 738.2 mAh·g−1 at 0.1 A g−1, respectively. [ABSTRACT FROM AUTHOR]

• Hierarchical SnS 2 -rGO microspheres are synthesized via coprecipitation and hydrothermal methods. • Hierarchical SnS 2 -rGO microspheres can alleviate volume variation of anodes. • Hierarchical hollow structures have obvious advantages for LIBs and SIBs. [Display omitted] SnS 2 with a two-step conversion and alloying mechanism, has now regarded as potential anode materials in both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). However, significant capacity attenuation caused by the tremendous volumetric change inhibits its practical application. Herein, the hierarchical microspheres constructed by SnS 2 nanosheets and S-doped graphene (SnS 2 -rGO) are synthesized via coprecipitation and hydrothermal methods. After 400 cycles at a current density of 1 A g−1, hierarchical SnS 2 -rGO microspheres can receive a superb reversible capacity of 1177.2 mAh g−1 in LIBs. After 400 cycles in SIBs, hierarchical SnS 2 -rGO microspheres can perform a charge capacity of 483.1 mAh g−1 at 0.5 A g−1. The single SnS 2 nanosheet with a thickness of 20 nm can facilitate the insertion/extraction of lithium/sodium-ion, which is helpful to improve the lithium/sodium storage capacity. In addition, a conductive network constructed by the S-doped graphene can boost electron migration. Sufficient volume expansion space can be offered by the hierarchical structure, which can as well as strengthen the contact with electrolytes. Thus, the hierarchical SnS 2 -rGO microspheres can be inferred as an ideal anode for LIBs and SIBs. [ABSTRACT FROM AUTHOR]

• Si@Cu@CC is synthesized by feasible methods of reduction and pyrolysis. • Copper shell can effectively buffer internal stress caused by volumetric expansion of silicon core. • Carbon cages constitute a conductive network which efficiently boost the cyclic and rate performance of Si. [Display omitted] Rationally surface optimization is considered to improve both energy capacity and structure stability in rechargeable batteries. A novel structure of copper coated silicon nanoparticles encapsulated in carbon cages (Si@Cu@CC) is synthesized by feasible methods of reduction and pyrolysis. The obtained composite exhibits a superior reversible capacity of 1724.3 mAh g−1 after 50 cycles at 0.1 A g−1, and the coulombic efficiency (CE) is 98.13%. It also maintains 1201.6 mAh g−1 even at the current density of 2 A g−1. The copper shell as a mechanical support layer wraps around the silicon nanoparticle can relieve the inner stress caused by the volumetric change. The exterior of Si@Cu particles is continuous network of carbon cages, which not only improves the conductivity of electrodes but also provides abundant transport channels for electrons and ions. The particular structure and the synergistic effect of copper and carbon have very important influence on the gorgeous properties of this composites. [ABSTRACT FROM AUTHOR]

• Nanoplates-assembled SnS 2 nanoflowers were synthesized by hydrothermal technology. • SnS 2 /C-rGO was synthesized by hydrothermal and low-temperature CVD technology. • Carbon layer and graphene can alleviate volume change and improve reversibility of conversion reaction of SnS 2. To meet people's requirements for higher performance Li-ion batteries (LIBs), many new types of anodes have been studied. Among them, the conversion reaction anode is considered to be a promising electrode based on the multi-electron reaction mechanism. As a typical conversion reaction anode, SnS 2 has been widely explored for its advantages of low toxicity, easy synthesis, and high capacity. However, it usually occurs the shuttle effect of polysulfide when applied, leading to the irreversibility of the conversion reaction, and seriously hinders its application. Therefore, we firstly employed hydrothermal and low-temperature chemical vapor deposition technology to prepare a ternary composite that flower-like SnS 2 anchored on reduced graphene oxide after coated carbon layer (SnS 2 /C-rGO). When applied in LIBs, SnS 2 /C-rGO displays a capacity of 952.8 mAh g−1 after cycling 90 times at 0.1 A g−1 and outstanding rate performance (479 mAh g−1 at 1 A g−1), which is significantly superior to other prepared electrodes. The high performance can be attributed to the synergistic effect of carbon layer and rGO, causing the high reversibility of conversion reaction and enhancing the cycle stability of SnS 2. This investigation may provide a reference for improving the reversibility of conversion reaction anode. [ABSTRACT FROM AUTHOR]

Silicon, to be a potential anode material of LIBs, possesses a pretty high lithium storage capacity. However, the structural integrity can be destructed by its huge volume expansion through cycles, which results in a large capacity attenuation. Meanwhile, the poor electrochemical performance of silicon-based anodes can be attributed to its poor conductance which reduces the reaction kinetics. According to the above challenges, core-shell structured silicon-nickel nanoparticles have been dispersed on 3D intertwined carbon nanotube networks (Si@Ni-NP/CNTs) via nitric acid pre-treatment and amino functionalization. The nickel-plated shell outside silicon core nanoparticles (Si@Ni-NP) can play a certain supporting role to prevent the volume expansion of silicon, which finally brings down the degree of powdering. Especially, the 3D framework composed of intertwined carbon nanotubes can efficiently provide not only an ample buffer space during intercalation/deintercalation but also a more stable conductive network to increase ion/electron transfer rate. Due to the above improvements in structural stability and reaction kinetics, Si@Ni-NP/CNTs reveal a reversible capacity of 1008 mAh g−1 with a 98% capacity retention over 100 cycles at a current density of 100 mA g−1. Under different current densities in rate test, the specific capacity recovery rate can reach 92%. The novel structure enables Si@Ni-NP/CNTs excellent stability under cycles and various rates, as a promising anode material of LIBs. [Display omitted] • 3D CNTs networks provide ion/electron transport channels Si@Ni-NP/CNT anodes. • 3D CNTs networks act as a dispersed matrix for Si@Ni-NP to inhibit reunion and buffer volume expansion. • The high performances of Si@Ni-NP/CNT result from nickel-plated layer and 3D CNTs networks. [ABSTRACT FROM AUTHOR]

Germanium-based materials are considered to be an alternative material for high energy density lithium-ion battery anodes due to their superior theoretical capacity. However, the severe volume expansion during the lithium insertion and the easily agglomerated tendency of Ge nanoparticles become the key obstacles to the stable cycle and capacity retention of Ge anodes. Herein, we designed a double-layered protective structure in which the cubic hollow Ge@C hybrids are uniformly dispersed on reduced graphene oxide sheets (Ge@C-rGO) through conventional dopamine-coated precursor and subsequent carbothermal reduction processes. In the synthesized Ge@C-rGO hybrids, the large-area rGO sheets cooperate with the amorphous carbon layer to accommodate and buffer the volume expansion of Ge particles, and to ensure that the Ge nanoparticles are in a separated state to the utmost extent. The Ge@C-rGO electrode which is employed in lithium-ion battery owns the reversible capacities of 1183 mAh·g−1 at the specific current of 100 mA g−1 and 710 mAh·g−1 at 1 A g−1 for 200 cycles. In addition, it exhibited good cycle stability, rate reversibility and electronic conductivity, and is a potential anode material with high performance and long-cycle capability. [ABSTRACT FROM AUTHOR]

Abstract On account of its high theoretical capacity and low cost, Fe 3 O 4 is regarded as a promising anode material for lithium-ion batteries. Nevertheless, many problems such as poor conductivity and volume expansion during lithiation severely limit its practical application. In this work, we synthesized hollow graphene spheres (HGSs) by self-assembly and innovatively combined it with Fe 3 O 4 particles to obtain a composite material. The Fe 3 O 4 /HGSs composite exhibits excellent electrochemical performances as an anode material, which behaves an initial discharge specific capacity of 1670.8 mA h g−1 at 50 mA g−1 and 1048.5 mA h g−1 after 50 cycles. Especially, the specific capacity can maintain as high as 617.1 mA h g−1 at the current density of 1000 mA g−1, which is much higher than that of commercial graphite. While largely inhibiting agglomeration between the particles of Fe 3 O 4 particles, hollow spheres composed of conductive and flexible graphene layers also provide an interconnected conductive network. We believe that this design in structure will also provide a new perspective for the researches of other transition metal oxides for lithium-ion batteries. Graphical abstract Image 1 Highlights • Fe 3 O 4 /HGSs composite was successfully fabricated by self-assembly of graphene oxide and in situ reduction of iron hydroxide. • The electrochemical performances of Fe 3 O 4 /HGSs composite are affected by the concentration of FeCl 3 solution. • Fe 3 O 4 /HGSs composite exhibits excellent lithium storage performance. [ABSTRACT FROM AUTHOR]

• Molten salt NaCl acts as a controllable self-assembled "liquid" interface of silicon crystal growth framework. • The properties of mesoporous silicon nanocrystals framework are affected by the ratio of mg powder and NaCl. • Regular closed-pore structure can provide abundant ion channels and charge transfer channels. Constructing porous silicon is one of the effective ways to ease the volume change (~320%) of the silicon-based anode. Thus, the design and construction of the porous structure of silicon by the particle size of Mg, the reaction temperature, ramp rate, and time of magnesiothermic reduction (MR) have achieved increasing attention. Here, a controllable self-assembled mesoporous diatomite-derived silicon nanocrystals framework (MRHDE-Si) can be adjusted directly by employing sodium chloride (NaCl) as a "liquid" interface via a MR method. As the proportion of Mg powder and NaCl increases from 1:0 to 1:10, the pore morphology level of MRHDE-Si changes from open-pore morphology to closed pore and tends to be more regular and affects the electrochemical performance of the electrode. Among as-prepared electrodes, the MRHDE-Si-5 electrode exhibits the optimal cycle performance that shows the specific capacity remains as high as 1290.9 mAh g-1 after 50 cycles at a current density of 200 mA g–1. Due to its smallest particle size of 23 nm, a suitable pore structure, pore volume (0.69 cm−3 g−1), the most feasible pore size (12.64 nm), which can provide abundant ion channels and charge transfer channels, shorten the diffusion path of Li+, enhance charge transfer capability, and effectively adapt to the stress caused by the volume expansion of Si as a buffering region. This "liquid" interface self-assembled strategy provides a simple and easy-to-operate way to design and prepare controllable porous silicon composite materials for applications in the field of new energy. [Display omitted] [ABSTRACT FROM AUTHOR]

• SiNP@NC cage was prepared by a facile and simple method. • The synergism of carbon cages and nitrogen-doped carbon improve the electrochemical performance. • The nitrogen-doped carbon cage can effectively accommodate the volume expansion of SiNP. ga1 Silicon is considered a valuable candidate for the anode material of lithium-ion batteries (LIBs) based on its high theoretical specific capacity and abundant resources in nature. Unfortunately, rapid capacity decay associated with volume expansion during cycling hinders the use of silicon in electrode materials for LIBs. Herein, we report nitrogen-doped carbon caging silicon nanoparticles (SiNP@NC cage) via simply coating and acid etching methods. The nitrogen-doped carbon shell can separate the silicon nanoparticles from the electrolyte, and the space between silicon nanoparticles and nitrogen-doped carbon cage offers adequate space for volume expansion of the silicon nanoparticles during the repeated cycling process. Besides, the amorphous carbon shell doped by nitrogen possesses more active sites on the surface. These properties are greatly conducive to the improvement of the electrochemical performance of silicon nanoparticles for Li-ion storage. The prepared SiNP@NC cage-2 manifests excellent electrochemical properties (1185.1 mAh g−1 after 100 cycles at the current density of 100 mA g−1) when being evaluated as the anode material in LIBs. [ABSTRACT FROM AUTHOR]

With the intensification of environmental pollution problems, the requirement for clean energy is increasing as time goes by. Currently, lithium-ion batteries (LIBs) composed of graphite anode cannot meet the commercial demand of human beings. Furthermore, considering the viewpoint that sodium-ion batteries (SIBs) were promising in large-scale energy storage, we synthesize a hybrid of SnS 2 nanoparticle-integrated graphene nanosheets (SnS 2 @GNS) by a facile and simple method. The unique structure that SnS 2 and GNS bonded by covalent bonds makes it displays excellent performance for lithium/sodium storage. Especially in LIBs, when tested at 0.1 A g−1, it delivers 1250.8 mA h g−1 after cycling 150 times which is much higher than previously reported Sn-based anode materials. In addition, it sustains 798.6 mA h g−1 without obvious capacity decay when the rate changed to 0.5 A g−1. Moreover, when employed in SIBs, it also delivers superior cycle performance (510.2 mA h g−1 after 100 cycles), which makes it possible to apply in LIBs and SIBs at the same time. Image 1 • SnS 2 nanoparticle-integrated graphene nanosheets were synthesized by a facile and simple method. • The addition of defective graphene can alleviate the volume change and provide more active sites for ion storage. • The SnS 2 @GNS electrode exhibits high reversible capacities for both lithium-ion batteries and sodium-ion batteries. [ABSTRACT FROM AUTHOR]

With the large-scale practical application of electric vehicles and mobile devices, more and more attention has been focused on the research of high specific capacity lithium-ion batteries (LiBs) anode materials. Novel graphene caging core-shell Si@Cu nanoparticles anchored on graphene sheets (Si@Cu@rGO) anode was prepared by deposition-precipitation and one-step thermal reduction methods. During the preparation, CuC 2 O 4 and graphene oxide are simultaneously reduced and coated on silicon nanoparticles. Introduced copper can enhance charge transfer kinetics of the electrode and suppress the tight cluster of Si nanoparticles. Besides, the graphene nanocage outside Si@Cu nanoparticle restricts polarization and pulverization of silicon inside itself. Graphene provides not only buffering space for core-shell Si@Cu nanoparticles to expand but also a conductive network to enhance the electronic conductivity and flexibility of the electrode. Therefore, the synergism of copper shells and graphene sheets improved electrochemical performance. The Si@Cu@rGO composites exhibited the reversible capacity of 2095.2 mAh g−1 at 200 mA g−1 after 50 cycles, showing extraordinary electrochemical performance. This outstanding Si@Cu@rGO anode becomes an ideal candidate for superior silicon-based lithium-ion battery applications. Image 1 • Si@Cu@rGO composite is fabricated by deposition-precipitation and one-step thermal reduction methods. • The synergism of copper shell and graphene greatly improved electrochemical performance. • Si@Cu@rGO anode exhibits high reversible capacity and excellent cycle capability. [ABSTRACT FROM AUTHOR]