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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]

In this work, hierarchical hexagonal nanoplates NiO composite with microcrystalline graphite are successfully synthesized by a hydrothermal process. Carbon nanofibers are disaggregated to the microcrystalline graphite and they are dispersed in NiO hexagonal structure (H–NiO sample). Microcrystalline graphite (1 wt% of the composite) has effect on growth NiO hexagonal nanoplates, improving the sample conductivity and stability. At the first cycle, H–NiO sample presents a high discharge capacity of 1357.2 mAh g−1 and a charge capacity of 1002.6 mAh g−1 with an initial coulombic efficiency of 73.9%. After 45 cycles, H–NiO sample exhibits a high reversible capacity of 1111.6 mAh g−1. The lithium diffusion coefficient of the H–NiO is calculated to be 7.517 × 10−12 cm2 s−1 with faster Li+ diffusion ability than pure NiO sample. The microcrystalline graphite in the composite electrode can effectively decrease the volume change and pulverization of NiO component, meanwhile, it hinders the aggregation in the cycled electrode. The microcrystalline graphite with intrinsic stability has potential application in producing composites with other metal oxides for highly reversible lithium storage capability. The as-produced microcrystalline graphite is in-situ composite with NiO hexagonal plates and play the key role in enhancement of electrochemical properties. The H–NiO nanoplates which is supported by microcrystalline graphite exhibits an excellent cycling stability, with a high reversible capacity of 1111.6 mAh g−1 at a current density of 100 mA g−1 after 45 cycles. Image 1 • Hierarchical hexagonal nanoplates NiO with microcrystalline graphite is synthesized. • Carbon nanofibers disaggregated to microcrystalline graphite and composite with NiO. • Microcrystalline graphite plays the key role in enhanced electrochemical properties. • H–NiO nanoplates presents discharge/charge capacities of 1357.2/1002.6 mAh g−1. • H–NiO exhibit reversible capacity of 1111.6 mAh g−1 after 45 cycles. [ABSTRACT FROM AUTHOR]