•Three-dimensional flower-like SnS2/CNTs is prepared by a hydrothermal method.•CNTs form a cross-winding network on the surface of SnS2 nano-plates.•The composites get a reversible capacity of 460 mA h g−1 at 20 mA g−1.Flower-like SnS2 fabricated by a novel hydrothermal approach are assembled by nano-plates with 1–2 µm in width and 5–10 nm in thickness. Carbon nanotubes are introduced to form a cross-winding network on the surface of SnS2 nano-plates, which improve the conductivity and Na+ diffusion of composites. The composites are explored as an anode for sodium-ion battery, and deliver an excellent rate performance. The composites get a reversible capacity of 460 mA h g−1 at 20 mA g−1 and 180 mA h g−1 even increased to 1280 mA g−1, which reveal the importance of carbon nanotubes network to optimize the fast charge-discharge capabilities of SnS2 flowers.

Li2ZnTi3O8/C nanocomposite has been synthesized using phenolic resin as carbon source in this work. The structure, morphology, and electrochemical properties of the as-prepared Li2ZnTi3O8 samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), Raman spectroscopy (RS), galvanostatic charge–discharge, and AC impedance spectroscopy. SEM images show that Li2ZnTi3O8/C was agglomerated with a primary particle size of ca. 40 nm. TEM images reveal that a homogeneous carbon layer (ca. 5 nm) formed on the surface of Li2ZnTi3O8 particles which is favorable to improve the electronic conductivity and inhibit the growth of Li2ZnTi3O8 during annealing process. The as-prepared Li2ZnTi3O8/C composite with 6.0 wt.% carbon exhibited a high initial discharge capacity of 425 and 159 mAh g−1 at 0.05 and 5 A g−1, respectively. At a high current density of 1 A g−1, 95.5 % of its initial value is obtained after 100 cycles.

•The rhombohedral Fe2O3 transforms to the cubic Fe3O4 via a calcination treatment.•Phase structure of anodes has great influences on their electrochemical performances.•Fe3O4/reduced graphene oxide shows a high capacity of 825.3 mAh g−1 at 50 mA g−1.The electrochemical performance of a material varies with its structural phase transition. It is found that the rhombohedral Fe2O3 can transform to the cubic Fe3O4 via a calcination treatment in a nitrogen atmosphere, and lithium-ion storage performances of Fe3O4 get an obvious improvement due to its structural advantages. On the basis of data calculated by X-ray diffraction, the larger unit cell volume as well as the higher void fraction of cubic Fe3O4 provides lithium-ions with more transport channels for Li ions diffusion and storage without serious volume change, and thus the cubic Fe3O4 delivers an excellent reversible capacity of 921.1 mAh g−1 after 15 cycles at the current density of 50 mA g−1, which is much higher than 328.3 mAh g−1 for the rhombohedral Fe2O3. To further enhance the structural stability of electrodes, reduced graphene oxide is introduced. The Fe3O4/reduced graphene oxide show an excellent specific capacity of 825.3 mAh g−1 after 40 cycles and impressive rate performance of 600 mAh g−1 at the current density of 400 mA g−1, which are much higher than that of Fe3O4 (417 and 300 mAh g−1), Fe2O3 (137.4 and 95 mAh g−1) and Fe2O3/reduced graphene oxide (390.1 and 480 mAh g−1). These results demonstrate that the structural phase transition and reduced graphene oxide of Fe3O4/reduced graphene oxide composites offer unique characteristics suitable for high-performance energy storage application.

•Inverse spinel structure relieves the irreversible phase transition of electrodes.•Anodes with the same structure show different discharge/charge conversion mechanisms.•High reversible capacity confirms the potential feasibility of composites.Inverse spinel transition metal oxides (Fe3O4, MnFe2O4, Fe3O4/reduced graphene oxide and MnFe2O4/reduced graphene oxide) are prepared by a facile ethylene-glycol-assisted hydrothermal method. The stability of inverse spinel structure and the high specific surface area of nanoscale provide transition metal oxides with high specific capacity. And the surface modification with reduced graphene oxide improves the poor conductivity of pristine transition metal oxides. Pristine Fe3O4 and MnFe2O4 deliver the high initial discharge capacity of 1137.1 and 1088.9 mAh g−1, respectively. Fe3O4/reduced graphene oxide and MnFe2O4/reduced graphene oxide get the reversible capacity of 645.8 and 720 mAh g−1, respectively, even after 55 cycles. The different discharge/charge conversion mechanisms make them different capacity stability. The great electrochemical performances of composites offer electrodes with suitable characteristics for high-performance energy storage application.

•Electrospun technique is employed to fabricate SiO2/C composite fibers.•SiO2/C fibers are curved and have a reticular structure with large specific surface areas.•SiO2/C fibers deliver a stable capacity at the current density of 50 mAh/g for 50 cycles.•SiO2/C fibers display excellent rate-capability.Electrospun together with thermal treatment is proposed to synthetize reticular amorphous SiO2/C composite fibers. The as-prepared fibers show carbon-coated SiO2 nanoparticles and form a space network structure, which cannot only improve the electrical conductivity, but also buffer the volume change. The SiO2/C fiber anode displays excellent performance, with an enhanced reversible capacity of 465 mAh/g at a current density of 50 mA/g up to 50 cycles, which is much higher than that of a pure SiO2 anode even at the first cycle (113.8 mAh/g). Favorable rate property (~ 240 mAh/g at a current density of 500 mA/g) also exhibits in the further electrochemical test. The excellent electrochemical properties are attributed to the carbon coat and the unique structure. These results suggest that the fiber materials can be used as an anode for rechargeable lithium-ion batteries.

•A two-step method is employed to fabricate polypyrrole@Mn3O4/reduced graphene oxide electrodes.•The electrodes coated with polypyrrole deliver a coulombic efficiency of ca.70%.•The composites deliver an initial discharge capacity of ca.1600 mAh g−1 at 60 mA g−1.A two-step method consisting of an in-situ transformation and an in-situ oxidative polymerization is employed to fabricate polypyrrole@Mn3O4/reduced graphene oxide composites. The resulting materials are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and Raman. The XRD analysis reveals the formation of Mn3O4/reduced graphene oxide and polypyrrole@Mn3O4/reduced graphene oxide. Mn3O4 particles coated with reduced graphene oxide and polypyrrole get an average diameter of ca.27 nm. The TEM images of polypyrrole@Mn3O4/reduced graphene oxide demonstrate that Mn3O4/reduced graphene oxide nanocomposites are indeed coated by a transparent polypyrrole film. The FT-IR studies disclose the characteristic functional groups between the respective materials. Moreover, Raman measurements confirm the reduction of graphite oxide to reduced graphene oxide. The result of electrochemical measurement demonstrates that it gets a high initial discharge capacity of ca.1600 mAh g−1 at 60 mA g−1 and the initial charge/discharge efficiency delivers a nice optimization after coated with polypyrrole (ca.45% VS ca.70%). The capacity of polypyrrole@Mn3O4/reduced graphene oxide can maintain at a level of ca.1000 mAh g−1 in the first five cycles and the rate performance of it is much better than that of Mn3O4/graphene.

The fabrication and electrochemical performance of Mn3O4/graphene composites are discussed in this work. The main reaction procedures consist of two parts: one is the formation of Mn3O4 particles and the other is the reduction of graphite oxide to graphene. The chemicals, MnCl2·4H2O and NaBH4 are employed as a manganese source and a reduction reagent, respectively. During the formation of Mn3O4 particles, NH3 is added to the reaction system, directly, which simplifies the hydrolysis of amide, and the surfactant, polyvinylpyrrolidone (PVP), is used to ensure great dispersion and size-controlled formation of Mn3O4 particles. The resulting materials are characterized by XRD, SEM, HRTEM, FT-IR, Raman and XPS. Mn3O4 particles dispersing on the surface of graphene have an average diameter of ca. 30 nm. The materials deliver a stable reversible capacity of ca. 500 mA h g−1 at a current density of 60 mA g−1 even after 100 cycles. The reversible capacity of the samples coated with graphene is much better than that of pure materials.

•An in-situ reaction method is employed to fabricate intercalated SiOC/graphene composites.•The mixture of TTCS and GO is first crosslinking and then pyrolyzed to form the intercalation structure.•It’s one-step preparation of SiOC/graphene composites, which the reduction and pyrolysis are completed simultaneously.•The 10GNS/SiOC composites deliver a stable capacity at the current density of 50 mAh/g for 90 cycles.Intercalated SiOC/graphene composites had been prepared by thermal reduction of TTCS/GO mixture, which was fabricated by dispersing GO into TTCS. Transmission electron microscopy (TEM) showed that SiOC nanoparticles were well encapsulated in a graphene matrix. The 10SiOC/graphene anode maintained a reversible capacity of 582 mAh/g after 90 cycles and had an initial coulombic efficiency of 63%. The excellent cycling stability is attributed to the fact that the SiOC/graphene composite can accommodate large volume change of SiOC and maintain good electronic contact. These results indicate that SiOC/graphene is an excellent anode material and has promising prospects in lithium ion batteries (LIBS) applications.

•A one-step hydrothermal method was employed to fabricate γ-MnS/rGO nanocomposites.•The γ-MnS/rGO delivered a capacity of ca. 600 mAh/g at 200 mA/g for 100 cycles.•The γ-MnS/rGO can still deliver a capacity of ca. 320 mAh/g even at 1000 mA/g.The synthesis, characterization and electrochemical study of γ-MnS/rGO nanocomposites are described in this work. A one-pot hydro-thermal method is employed to fabricate γ-MnS/rGO electrodes. l-cysteine is used as sulfur source as well as the reduction of GO to rGO. The resulting materials are characterized by XRD, SEM, TEM, FT-IR and TG. Γ-MnS particles dispersing on the surface of reduced graphene oxide have the average diameter of ca. 37 nm. As a splendid anode material for lithium-ion batteries, γ-MnS/rGO nanocomposites achieve a stable specific capacity of ca. 600 mAh/g at a current density of 200 mA/g for 100 cycles and deliver a great rate performance (a reversible capacity of ca. 320 mAh/g even at a high current density of 1000 mA/g). All of these electrochemical performances are greater than those of the pristine MnS.

•In-situ synthesis of nano-Li4Ti5O12/C composite using PVP as carbon source by a solid-state reaction.•A thin and homogeneous carbons layer, as well as the limited particle size is achieved.•The carbon-coated Li4Ti5O12 exhibits high rate performance.In-situ coating approach using polyvinyl pyrrolidone (PVP) as carbon source is introduced in this work with the aim of getting high rate Li4Ti5O12/C composite. Li4Ti5O12/C composite, particle size of 50–200 nm in diameter, is well dispersed and the carbon layers are 2–4 nm in thickness. Li4Ti5O12/C composite delivers much higher electrochemical performance than Li4Ti5O12, in terms of reversible discharge capacity and rate performance. It exhibits high discharge capacities of 172 mAh g− 1 and 141 mAh g− 1 at 0.2 C and 10 C-rate, respectively. 95.7% of its initial capacity is retained after 200 cycles at 10 C, demonstrating good cycling stability.

The CuS@reduced graphene oxide (CSG) was synthesized and used as an anode material in lithium ion batteries (LIBs). CuS nanoparticles were homogeneously dispersed on the surfaces of reduced graphene oxide (rGO) nanosheets via a hydrothermal method. The rGO nanosheets in the CSG hydrids can improve the electrical conductivity and structure stability of CSG. The LIB with a CSG anode displays excellent performance, with a first discharge capacity up to 851 mAh/g, a reversible capacity of 648.1 mAh/g in the initial cycle, and an enhanced cyclic performance with a discharge capacity of 710.7 mAh/g at the 100th cycle, which corresponds to 114.3% of the theoretical value of CSG and 83.5% of the first discharge capacity accompanied by an excellent Coulombic efficiency of 99.1% at a current density of 0.2 C, which is much larger than (close to 4.5 times) that with a pure CuS anode at the 100th cycle (159.7 mAh/g). This phenomenon can be attributed to the synergistic action of CuS nanoparticles and rGO nanosheets in the “double-sandwich-like” CSG hybrids. These results indicate that CSG is an excellent anode material and has promising prospects in lithium ion batteries applications.CuS@reduced graphene oxide displays excellent electrochemical behavior as an anode material for Lithium ion batteries.

Silicon monoxide/graphite/multi-walled carbon nanotubes (SiO/G/CNTs) material was prepared by ball milling followed by chemical vapor deposition method and characterized by X-ray diffraction, scanning electron microscopy (SEM), galvanostatic charge–discharge, and AC impedance spectroscopy, respectively. The results revealed that SiO/G/CNTs exhibited an initial specific discharge capacity of 790 mAh g−1 with a columbic efficiency of 65%. After 100 cycles, a high reversible capacity of 495 mAh g−1 is still retained. The improved electrochemical properties were due to beneficial SEI by the SEM and EIS results.