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One-dimensional copper sulfide (CuS) wires were realized by the acrylamide-assisted hydrothermal process using Cu(NO3)2 and thiourea (NH2CSNH2) as reactants at 100 °C. A copper sulfide/carbon nanotube (CNTs) composite was fabricated as a similar method with the addition of CNTs. The samples are characterized by XRD, SEM, TEM, and Raman scattering spectra, respectively. The influence of reaction temperature and amine on the morphologies of CuS nanocrystals was investigated. As anode materials for sodium-ion batteries, the electrochemical studies show that the CuS/CNT composite electrode delivers a higher reversible capacity of 428.1 mA h g−1 at 0.1 A g−1 for the 100th cycle, because CNTs can be a conductive agent to provide a fast path for electron transportation, compared with the bare CuS wires (280 mAh·g−1 after 100 cycles). The synthesis results indicate that the amine-directed synthesis strategy of copper sulfide could be extended for the preparation of other metal sulfide nanostructures. Further, the incorporation of the CNT matrix into the copper sulfide is an effective approach to enhance the electrochemical performance of CuS. [ABSTRACT FROM AUTHOR]

FeS2/CoS and FeS2/CoS/C composites were synthesized by solvothermal method and following vapor phase vulcanization at mild temperature with binary oxide CoFe2O4 as precursors. All FeS2/CoS composites prepared at different molar ratios of Fe3+ and Co2+ ions exhibit the similar morphology of solid microspheres. As anode materials for lithium-ion batteries (LIBs), the as-prepared FeS2/CoS and FeS2/CoS/C composites show higher reversible capacity and better cycling performance, compared with the bare FeS2 and CoS. Among them, the FeS2/CoS composite with molar ratio of Fe3+ and Co2+ of 2:1 exhibits the high reversible capacity of 1150 mAh g−1 after 100 cycles at 100 mA g−1 and even 610 mAh g−1 at 1.0 A g−1 after 900 cycles. This strategy for synthesizing the heterogeneous structure of binary sulfide can effectively improve the kinetic which thus enhance the electrochemical performance of materials. This work can provide an effective method and idea for the preparation and modification of FeS2 and other transition metal sulfide anode materials for LIBs in the future. [ABSTRACT FROM AUTHOR]

Mn3O4 and Mn3O4 (140)/CNTs have been investigated as high-capacity anode materials for lithium-ion batteries (LIBs) applications. Nanoparticle Mn3O4 samples were synthesized by hydrothermal method using Mn(Ac)2 and NH3·H2O as the raw materials and characterized by XRD, TG, EA, TEM, and SEM. Its electrochemical performances, as anode materials, were evaluated by galvanostatic discharge-charge tests. The Mn3O4 (140)/CNTs displays outstanding electrochemical performances, such as high initial capacity (1942 mAh g−1), stable cycling performance (1088 mAh g−1 and coulombic efficiency remain at 97% after 60 cycles) and great rate performance (recover 823 mAh g−1 when return to initial current density after 44 cycles). Compared to pure Mn3O4 (140), the improving electrochemical performances can be attributed to the existence of very conductive CNTs. The Mn3O4 (140)/CNTs with excellent electrochemical properties might find applications as highly effective materials in electromagnetism, catalysis, microelectronic devices, etc. The process should also offer an effective and facile method to fabricate many other nanosized metallic oxide/CNTs nanocomposites for low-cost, high-capacity, and environmentally benign materials for LIBs. [ABSTRACT FROM AUTHOR]