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The use of inexpensive graphite oxide (GO) as a carbon source, instead of the expensive reduced graphene oxide (rGO), is essential to prepare metal oxide/rGO composites. In this work, we investigated the in situ reaction of GO and FeCl3 to produce Fe2O3/rGO composites as anode materials for high‐energy lithium‐ion batteries (LIBs). In this reaction, iron ions combined with the oxygen‐containing functional groups of GO, which subsequently grew into Fe2O3 nanoparticles, whereas the GO transformed into rGO under hydrothermal conditions. In the composite Fe2O3−rGOx samples, intergranular gaps in the Fe2O3 sub‐micron particles evidently increased the contact between the Fe2O3 active material and the electrolyte, which improved the Li‐ion conductivity and electrochemical performance of the Fe2O3−rGOx composites. The Fe2O3−rGO2 sample showed the best cyclic performance and delivered the highest capacity of all samples. The initial discharge and charge capacities of Fe2O3−rGO2 were 1086.3 and 722.4 mAh g−1, respectively. After 100 cycles, the discharge specific capacity of Fe2O3−rGO2 was 653.2 mAh g−1 and the coulombic efficiency was 98.4 %. We found that an appropriate weight ratio and composite morphology of Fe2O3−rGOx were important in influencing the electrochemical properties of the composite anode materials for high‐energy LIBs. [ABSTRACT FROM AUTHOR]

Summary: The heterostructural construction of metal disulfide/oxide is essential in the electrochemical performance as anode material for lithium‐ and sodium‐ion batteries (LIBs and SIBs). In this work, an integrated composite of molybdenum disulfide (MoS2) and hexagonal molybdenum dioxide (MoO2) together enwrapped in reduced graphene oxide (rGO) is synthesized under hydrothermal condition. In the pelletizing MoS2‐MoO2/rGO composite, rGO as substrate effectively prevents the restacking and pulverization of MoS2‐MoO2 during a long cycling process. Meanwhile, the synergistic effect among the MoS2, MoO2, and rGO components are responsible for abundant active sites and shorten ionic transport channels. When evaluating as anode material for LIB, MoS2‐MoO2/rGO sample presents excellent cyclic performance and still delivers a high capacity of 1062.3 mA h g−1 after 120 cycles at 0.2 A g−1; evaluating in a SIB at 0.04 A g−1, it presents excellent cyclic performance and delivers 430 mA h g−1 at the 80th cycle. The heterostructural composite MoS2‐MoO2/rGO is one of the candidate anode materials for high‐performance LIB and SIB. [ABSTRACT FROM AUTHOR]

Three dimensional networks, herein carbon coated SnO 2 micron-sized particles are fixed in carbon nanofibers (CNF/SnO 2 @C), is fabricated and synthesized by using hydrothermal method and carbonization. The weight ratio of SnO 2 reaches to 50% of CNF/SnO 2 @C, meanwhile, CNF/SnO 2 @C remains its flexibility. CNF/SnO 2 @C film is directly used as a binder-free anode for lithium ion batteries without conductive additive and polymer binder. The discharge capacities of CNF/SnO 2 @C are 1286 mAh g −1 at 0.05 A g −1 and 397 mAh g −1 at 1 A g −1 , respectively. The buffering effect of CNFs is studied by using ex-situ SEM in the cycled electrodes operated at various lithiation states. The particles size of SnO 2 @C sample increase to 4 μm after 20 charge/discharge cycles, and a serious aggregation of particles occurs in the cycled SnO 2 @C electrode which is in coincidence with its rapidly faded capacity. The particles of CNF/SnO 2 @C sample also present the increased size from the original size of 2 μm to the lithiated size of 4 μm but they are still fixed in CNFs network without any aggregation. The improved specific capacity, cyclic stability and rate performance of CNF/SnO 2 @C are attributed to the structural synergy of CNFs and SnO2 particles, because CNFs as flexible substrate provides excellent conductive channel improving the rate capability and effective network buffering the volume change to promote the cyclic performance. [ABSTRACT FROM AUTHOR]

A series of composites manganese oxide/carbon with one-dimensional structure are synthesized using electrospinning. The phase composition, morphology and electrochemical performance of MnO x /carbon are studied, which affected by the manganese concentration in precursor and subsequent carbonization conditions. The manufacture of MnO x /carbon is composed of two steps including thermal stabilization (at 250 °C in air) and carbonization (at 700 °C in nitrogen). The main functional groups of samples are well identified by FT-IR spectra. The sample Mn33_3h with the lowest manganese content presents the construction structure which amorphous and/or nanosized MnO x with smaller crystal size are grown and enwrapped in carbon fiber during carbonization. Mn33_3h presents the initial charge and discharge capacities of 1054.1 and 665.6 mAh g−1, and the discharge capacity at the 50th cycle remains 99.7% of that at the 2nd cycle. Beside the well rate capability at the range of current densities from 20 to 1000 mA g−1, Mn33_3h presents very good recovery ability after high rate cycling at 1000 mA g−1. The advantages of this composite structure as well as its high capacity make manganese oxide a very attractive candidate as an anode material for the next generation of rechargeable lithium ion batteries. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The α-Fe 2 O 3 grains were grafted onto the TiO 2 /CNFs via the vapor-solid reaction. • The TiO 2 /CNFs reserved void space to suppress the disintegration of the Fe 2 O 3. • The 3D network provide interstitial sites and enhanced pathways for Li+ and e−. Abstract α-Fe 2 O 3 grains grafted onto TiO 2 /carbon nanofibers (CNFs) for use as anode materials in lithium-ion batteries have been successfully fabricated by electrospinning and vapor-solid reaction (VSR). Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N 2 adsorption-desorption isotherms reveal that the ultrafine α-Fe 2 O 3 nanoparticles were formed on the TiO 2 /CNFs and have uniform dispersion along the fiber direction. The VSR approach could retard nucleation, thus making TiO 2 /CNFs with small Fe 2 O 3 grains grafting (approximately 5 nm in diameter). The TiO 2 /CNFs are capable of buffering the large volume variation of α-Fe 2 O 3 during cycling and preventing electrode pulverization and aggregation, as well as providing sufficiently large interstitial space within the crystallographic structure to host Li ions. The electrochemical properties of the composite electrodes were tested by galvanostatic cycling at both constant and variable current rates. The composite delivers both good rate capability under an uprated current density of 1000 mA g−1 and especially enhanced cycle stability (∼600 mA h g−1 after 200 cycles at a current density of 1000 mA g−1). The super electrochemical performance is attributed to a synergetic effect between α-Fe 2 O 3 and TiO 2 -CNFs as well as the three- dimensional (3D) network, which contributes to greatly enhanced diffusion kinetics and structural stability for lithium-ion batteries. This VSR approach can be extended to other hierarchical metal oxide nanostructures for favorable applications in electrochemical devices. [ABSTRACT FROM AUTHOR]

A novel heterostructure of NiO/Ni 3 S 2 nanoflake is synthesized and composited with carbon nanofibers (CNF) membrane. NiO/Ni 3 S 2 nanoflakes are homogeneously dispersed in CNF network, herein, NiO/Ni 3 S 2 like leaf and CNF like branch. Carbon nanofibers network efficiently prevents the pulverization and buffers the volume changes of NiO/Ni 3 S 2 , meanwhile, NiO/Ni 3 S 2 nanoflakes through the conductive channels of carbon nanofibers own improved Li + diffusion ability and structural stability. The capacity of NiO/Ni 3 S 2 /CNF reaches to 519.2 mA g −1 after 200 cycles at the current density of 0.5 A g −1 while NiO/Ni 3 S 2 fades to 71 mAh g −1 after 40 cycles. Owing to the synergetic structure, the resultant binder-free electrode NiO/Ni 3 S 2 /carbon nanofibers shows an excellent reversible lithium storage capability. [ABSTRACT FROM AUTHOR]