RESUMO
Pure CuC2O4·xH2O and CuC2O4·xH2O/carbon nanotubes (CNTs) composites are synthesized by a low-temperature hydrothermal process. The structure and morphology of the products are analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TG) and Raman spectrum. The results demonstrate that the as-prepared CuC2O4·xH2O takes on a microsphere-like morphology, all CuC2O4·xH2O/CNTs nanocomposites are constructed by the intertwining of tabular CuC2O4·xH2O nanoparticles (NPs) and CNTs to form a tanglesome net. When evaluated as an anode materials for lithium ion batteries (LIBs), all CuC2O4·xH2O/CNTs electrodes possess higher reversible discharge capacities (more than 1000 mAh g-1) than the pure CuC2O4·xH2O, up to 200th cycle at a current density of 100 mA g-1. The results illustrate that the addition of CNTs can enhance the electrochemical performance of CuC2O4·xH2O. Overall, CuC2O4·xH2O/CNTs composite can be a promising candidate used as a promising anode for LIBs.
RESUMO
α-Fe2O3 and Cu-doped α-Fe2O3 microspheres were similarly synthesized by solvothermal method. These microspheres were characterized by X-ray diffraction (XRD), and scanning electron microscope (SEM) technique. As anode materials for lithium-ion batteries (LIBs), Cu-doped α-Fe2O3 electrodes exhibit better electrochemical performance (higher specific capacities of 600 mAhg-1 and better cycling performance), compared with pure α-Fe2O3 electrode. Additionally, the effects of different Cu2+-doping contents and reaction times on the morphology and the electrochemical properties were also discussed. Cu-doped α-Fe2O3 proves to be a potential anode material for LIB applications.
RESUMO
Zn1-xCoxCO3 (ZCCO) microspheres were synthesized by a modified solvothermal method (ball milling-solvothermal combination method) using ZnCl2, CoCl2, and NH4HCO3 as raw materials. All samples were characterized by X-ray diffractometer (XRD), Fourier transform infrared spectra (FT-IR), and Scanning electron microscopy (SEM) technique. The results showed the introduction of Co and molar ratio of Zn and Co play crucial roles in the morphology and electrochemical performance of the ZCCO. As anode materials for lithium ion battery (LIB), all ZCCO electrodes possess high specific capacities and good cycle performance. The as-obtained Zn0.5Co0.5CO3 electrode exhibits higher discharge capacity (1526 mAh/g) and better rate properties with the reversible capacity of 976 mAh/g after 100 cycles when the molar ratio of Zn/Co is 1:1. Moreover, the present work provides a new and simple approach to the fabrication of novel anode materials (transition metal carbonates) for LIB applications.
RESUMO
NiCO2S4 with different morphology was controllably fabricated by a facile hydrothermal and solvothermal route. The as-obtained samples were analyzed and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The results reveal that the sample (NCS-1) prepared by hydrothermal method manifest a mixture of nanorods and nanospheres. The sample (NCS-2) synthesized by solvothermal process takes on spherical nanoparticles (NPs). It is found that the morphology of the sample has much influence on the electrochemical property. When applied as anode for lithium-ion batteries (LIBs), the NiCO2S4 NPs (NCS-2) possess the highest reversible discharge capacity of 1469.8 mAh g-1 compared with other two samples at the current density of 100 mA g-1 in the voltage window of 0.01-3 V. Additionally, it remains a specific capacity of 1163.7 mAh g-1 at a current density of 100 mAg-1 after 100 cycles. This excellent electrochemical performance arises from its unique mesoporous structure, which can reduce the transport lengths of both lithium ions and electrons. The mesoporous NiCO2S4 NPs show the great potential development of high-capacity anode materials for LIBs.
