RESUMO
In this study, we synthesize nanostructured NdMnxFe1-xO3 perovskites using a facile method to produce materials for the high-working-efficiency anodes of Li-ion batteries. A series of characterization assessments (e.g., X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and electron microscopy) were conducted, and the results confirmed the efficacious partial replacement of Fe ions with Mn ions in the NdFeO3 perovskite structure, occurrence of both amorphous and crystalline structures, presence of oxygen vacancies (VO), and interconnection between nanoparticles. The possibility of Mn ion replacement significantly affects the size, amount of VO, and ratio of amorphous phase in NdMnxFe1-xO3 perovskites. The NdMnxFe1-xO3 perovskite with x = 0.3 presents a notable electrochemical performance, including low charge transfer resistance, durable Coulombic efficiency, first-rate capacity reservation, high pseudo-behavior, and elongated 150-cycle service life, whereas no discernible capacity deterioration is observed. The reversible capacity of the anode after the 150th-cylcle was 713 mAh g-1, which represents a high-capacity value. The outstanding electrochemical efficiency resulted from the optimum presence of VO, interconnection between the nanoparticles, and distinctive properties of the NdFeO3 perovskite. The interconnection between nanoparticles was advantageous for forming a large electrolyte-electrode contact area, improving Li-ion diffusion rates, and enhancing pseudocapacitive effect. The attributes of perovskite crystals, coexistence of Mn and Fe throughout the charge/discharge process, and optimum VO precluded the electrode devastation that caused the Li2O-phase decomposition catalysis, enabling favorable reversible Li storage.
RESUMO
A novel composite, FexSnyOz, consisting of tin oxide and iron oxide was developed via a galvanic replacement reaction. The morphology, crystalline structure, and composition of the FexSnyOz composite were investigated by employing X-ray diffraction, energy dispersive X-ray spectroscopy, and transmission electron microscopy. When evaluated as an anode material using different binders, namely, polyvinylidene fluoride (PVDF) and poly(acrylic acid) (PAA), the composite blended with the PAA binder displayed a high coulombic efficiency and excellent cycling stability compared to the composite mixed with the PVDF binder. The excellent electrochemical performance could be attributed to the different interactions between the current collector and the binders, as well as the volume accommodation during cycling. Therefore, the results indicated that the application of an appropriate binder could lead to a significant improvement in the electrochemical performance of FexSnyOz composite anodes for lithium-ion batteries.
RESUMO
We have synthesized a novel composite material Sn/SnO/Ni3Sn via galvanic replacement reaction between Sn and Ni2+ ions in triethylene glycol medium and at high temperature. The reaction time affected structure, particle size, and composition of Sn/SnO/Ni3Sn composites, which were analyzed by high resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. The active component (Sn) reacts with Li+ ions while inactive component (Ni) acts as a metal framework to support the electrochemically active Sn, a buffer to reduce volume change during cycling, and the electron conductor. Among electrodes, the Sn/SnO/Ni3Sn-6h electrode demonstrated stable cycling and reversible capacity of 246 mAh g-1 even after 300 cycles owing to the advantages from the unique hybrid structure.