Controllable Synthesis of Carbon-Coated SiO_x Particles through a Simultaneous Reaction between the Hydrolysis–Condensation of Tetramethyl Orthosilicate and the Polymerization of 3-Aminophenol

Abstract

Core–shell particles are desirable for many applications, but the precise design and control of their structure remains a great challenge. In this work, we developed a strategy to fabricate carbon-coated SiO x (SiO x @C) core–shell particles via a sol–gel method using the simultaneous hydrolysis–condensation of tetramethyl orthosilicate (TMOS), the polymerization of 3-aminophenol and formaldehyde in the presence of ammonia as a basic catalyst, and cetyl­tri­methyl­am­monium bromide (CTAB) as a cationic surfactant in the mixed solution of water and methanol followed by the carbonization process. Results from this study provide new insight into the design of core–shell particles by using TMOS as an effective silica precursor for the first time with a well-controlled reaction rate and spherical morphology. To obtain an in-depth understanding of the formation of core–shell structure, a possible mechanism is also proposed in this article. When tested as an anode material for lithium ion batteries (LIBs), the obtained SiO x @C particles delivered a reversible capacity of 509.2 mAh g–1 at a current density of 100 mA g–1. This electrochemical performance is significantly better than those of similar composites without the core–shell structure. The capacity retention after 100 cycles was approximately 80%. These results suggest great promise for the proposed SiO x @C particles with core–shell structure, which may have potential applications in the improvement of various energy-storage materials.

Nitrogen-Enriched Carbon Nanobubbles and Nanospheres for Applications in Energy Harvesting, Storage, and CO2 Sequestration

“…This is a modified Stöber reaction, illustrated in Scheme . The similar reaction mechanism was adopted for the synthesis of hollow carbon nanobubbles (CNB) whereby TEOS was hydrolyzed and condensed (see compounds (1) and (2)) to form the core, and the RF resin acted as the carbon precursor covering the outer shell. , The reaction between the resorcinol and formaldehyde (7) results in intermediates diffusing on the surface, an effect of the presence of NH 4 + , results in the formation of a polymeric resin sphere. , A stable colloidal suspension of the negatively charged sphere surrounded by positively charged NH 4 + is formed, the interaction of which stabilizes and prevents the spheres from agglomerating . Further, after the hydrothermal reaction, core SiO 2 is etched by HF with the above carbonization step to obtain hollow carbon nanobubbles.…”

Recent Progress of Microwave-Assisted Synthesis of Silica Materials

“…The main drawback of such substitution, the lower capacity delivered in batteries of SiO x in comparison with Si, can be overtaken adding a conductive layer like carbon or graphite. Taking this into account, Ogi et al developed two microwave-assisted procedures to easily prepare carbon-SiO x particles for Li-ion battery anodes [ 73 , 74 ] ( Scheme 4 ).…”

“…In the second paper, the authors synthesized carbon-coated SiO x (SiO x @C) core–shell particles [ 74 ]. Again, two stages were required.…”

“… Synthesis scheme for the microwave assisted synthesis of C/SiO x nanocomposite [ 73 ] and SiO x @C [ 74 ]. …”

Si(CO)y Negative Electrodes for Li-Ion Batteries

“…Most of these studies have used either innovative electrode structures or silicon-based composite materials. Improvements have been made by reducing the Si grain size, controlling crystallization, , forming alloys/composites with other elements, − carbon coating, − etc. A great amount of effort is still being applied to propose practical solutions for commercialization and to improve performance further.…”