ABSTRACT
The development of novel materials is essential for the next generation of electric vehicles and portable devices. Tin oxide (SnO2), with its relatively high theoretical capacity, has been considered as a promising anode material for applications in energy storage devices. However, the SnO2 anode material suffers from poor conductivity and huge volume expansion during charge/discharge cycles. In this study, we evaluated an approach to control the conductivity and volume change of SnO2 through a controllable and effective method by confining different percentages of SnO2 nanoparticles into carbon nanotubes (CNTs). The binder-free confined SnO2 in CNT composite was deposited via an electrostatic spray deposition technique. The morphology of the synthesized and deposited composite was evaluated by scanning electron microscopy and high-resolution transmission electron spectroscopy. The binder-free 20% confined SnO2 in CNT anode delivered a high reversible capacity of 770.6 mAh g-1. The specific capacity of the anode increased to 1069.7 mAh g-1 after 200 cycles, owing to the electrochemical milling effect. The delivered specific capacity after 200 cycles shows that developed novel anode material is suitable for lithium-ion batteries (LIBs).
ABSTRACT
The micro-arc oxidation/graphene oxide (MAO/GO) composite coatings were successfully prepared on the surface of magnesium alloys by the MAO and electrodeposition technologies. The morphology and composition of the MAO/GO composite coatings were characterized by scanning electron microscopy, energy-dispersive spectrometry, X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis spectroscopy, Raman spectroscopy, roughness test, and binding test. The electrochemical impedance spectroscopy, polarization curve, and immersion test were used to evaluate the protection performance of MAO/GO composite coatings provided to a substrate. The test results showed that GO covered the surface of the MAO film and had a multilayer structure in the composite coatings. The composite coatings performed the function of sealing the micropores of the MAO film. The elements in the surface of the composite coatings were evenly distributed and the C element content was high. We find that the composite coatings were smoother than the MAO film. The bonding force of the composite coating needs to be enhanced. The corrosion resistance of the MAO/GO composite coatings was obviously better than that of a single MAO film.
