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Variation in Crystalline Phases: Controlling the Selectivity between Silicon and Silicon Carbide via Magnesiothermic Reduction using Silica/Carbon Composites

Title
Variation in Crystalline Phases: Controlling the Selectivity between Silicon and Silicon Carbide via Magnesiothermic Reduction using Silica/Carbon Composites
Author
유원철
Keywords
LITHIUM-ION BATTERIES; MESOPOROUS SILICON; ORDERED MESOPOROSITY; REVERSIBLE STORAGE; ANODE MATERIALS; ENERGY-STORAGE; SURFACE-AREAS; CARBON; PERFORMANCE; POWDER
Issue Date
2016-03
Publisher
AMER CHEMICAL SOC
Citation
CHEMISTRY OF MATERIALS, v. 28, No. 5, Page. 1526-1536
Abstract
Magnesiothermic reduction of various types of silica/carbon (SiO2/C) composites has been frequently used to synthesize silicon/carbon (Si/C) composites and silicon carbide (SiC) materials, which are of great interest in the research areas of lithium-ion batteries (LIBs) and nonmetal oxide ceramics, respectively. Up to now, however, it has not been comprehensively understood how totally different crystal phases of Si or SiC can result from the compositionally identical parent materials (SiO2/C) via magnesiothermic reduction. In this article, we propose a formation mechanism of Si and SiC by magnesiothermic reduction of SiO2/C; SiC is formed at the interface between SiO2 and carbon when silicon intermediates, mainly in situ-formed Mg2Si, encounter carbon through diffusion. Otherwise, Si is formed, which is supported by an ex situ reaction between Mg2Si and carbon nanosphere that results in SiC. In addition, the resultant crystalline phase ratio between Si and SiC can be controlled by manipulating the synthesis parameters such as the contact areas between silica and carbon of parent materials, reaction temperatures, heating rates, and amount of the reactant mixtures used. The reasons for the dependence on these synthesis parameters could be attributed to the modulated chance of an encounter between silicon intermediates and carbon, which determines the destination of silicon intermediates, namely, either thermodynamically preferred SiC or kinetic product of Si as a final product. Such a finding was applied to design and synthesize the hollow mesoporous shell (ca. 3-4 nm pore) SiC, which is particularly of interest as a catalyst support under harsh environments.
URI
https://pubs.acs.org/doi/abs/10.1021/acs.chemmater.5b05037http://repository.hanyang.ac.kr/handle/20.500.11754/102197
ISSN
0897-4756; 1520-5002
DOI
10.1021/acs.chemmater.5b05037
Appears in Collections:
COLLEGE OF SCIENCE AND CONVERGENCE TECHNOLOGY[E](과학기술융합대학) > CHEMICAL AND MOLECULAR ENGINEERING(화학분자공학과) > Articles
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