Silicon-based
anodes are of particular interest for the application of next generation
large-capacity lithium-ion batteries (LIBs) because of their natural
abundance and ultrahigh theoretical lithium storage ability. However,
the huge volume expansion and inferior cyclic stability severely limit
their practical applications. To address this challenge, herein, hollow
cubelike hybrid composites consisting of a Si/SiO2 cross-link
covered by a carbon layer (Si/SiO2@C) have been rationally
synthesized through a facile zeolitic imidazolate framework template
method. Within hybrid composites, the porous Si/SiO2 cross-link
with an internal void can effectively mitigate volume changes and
facilitate fast channels for Li+ during the charge–discharge
process while the coated carbon layer not only can improve the electrical
conductivity of the composites but also guarantees the structural
integrity. As expected, the hollow Si/SiO2@C composite
electrode has outstanding electrochemical properties including excellent
reversible capacity (1280 mAh g–1 at 500 mA g–1 after cycled for 200 times) and superior rate performance
(782 and 660 mAh g–1 at current densities of 3.2
and 6.4 A g–1, respectively). Considering the convenient
preparation and naturally abundant of composites as well as their
excellent electrochemical performance, the hollow Si/SiO2@C may hold great promise as advanced electrodes for next-generation
LIBs.
A hexagonal boron nitride (h-BN) coating of micron thickness is deposited directly on 316L stainless steel (SS316L) cathode through efficient, adjustable electrophoretic deposition (EPD) in a suspension system containing surfactant and ethanol. It is based on the mixing of h-BN with polyethyleneimine (PEI) resulting in positively charged ceramic powder making cathodic electrophoretic deposition possible. The thickness of the resulting h-BN coatings deposited on SS316L could be controlled by varying the time and the voltage of electrophoretic deposition. The deposition kinetics and mechanism have been discussed. After soaking in Al(H2PO4)3 solution and high-temperature annealing, the h-BN coatings exhibited good adhesive strength. Furthermore, a novel method has been used for the evaluation of the adhesive strength to explore the appropriate experimental conditions. X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were employed to characterize the h-BN coatings. The h-BN coatings are applied for the DC breakdown performance test and exhibit remarkable breakdown voltage and breakdown strength.
In this paper, we reported on the preparation of porous materials via a reaction under Autogenic Pressure at Elevated Temperature (RAPET) at 700°Cusing natural product and alkoxides as precursors. The RAPET is a new simple efficient method to prepare inorganic materials. The porous carbon and its composite materials were prepared via the method of RAPET using natural products such as sweet potato, coriander, the absorbent cotton and viscose fiber doped by tetrabutyl titanate (TBOT) and tetraethoxysilane (TEOS). The reaction temperature of RAPET was 700°C. The carbon and its composites were studied with scanning electron microscopy (SEM), X-ray diffraction (XRD) and nitrogen adsorption-desorption measurements. The BET surface area of the materials are different from 4m2/g to 405m2/g. The XRD investigation indicates that the phases of the TiO2 in the carbon/TiO2 composites are anatase. The materials show a certain charge-discharge performance.
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