Green Fabrication of Silkworm Cocoon-like Silicon-Based Composite for High-Performance Li-Ion Batteries.
basic_science · Level V
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- Record sourced from PubMed, PMID 28800223.
- Also identified by DOI 10.1021/acsnano.7b03830.
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Abstract
Designing yolk-shell nanostructures is an effective way of addressing the huge volume expansion issue for large-capacity anode and cathode materials in Li-ion batteries (LIBs). Previous studies mainly focused on adopting a SiO<sub>2</sub> template through HF etching to create yolk-shell nanostructures. However, HF etching is highly corrosive and may result in a significant reduction of Si content in the composite. Herein, a silkworm cocoon-like silicon-based composite is prepared through a green approach in which Al<sub>2</sub>O<sub>3</sub> was selected as a sacrificial template. The void space between the outer nitrogen-doped carbon (NC) shell formed by chemical vapor deposition using a pyridine precursor and the inside porous silicon nanorods (p-Si NRs) synthesized by magnesiothermic reduction of ordered mesoporous silica nanorods can be generated by etching Al<sub>2</sub>O<sub>3</sub> with diluted HCl. The obtained p-Si NRs@void@NC composite is utilized as an anode material for LIBs, which exhibits a large initial discharge capacity of 3161 mAh g<sup>-1</sup> at 0.5 A g<sup>-1</sup>, excellent cycling behavior up to 300 cycles, and super rate performance. Furthermore, a deep understanding of the mechanism for the yolk-shell nanostructure during the Li-alloying process is revealed by in situ transmission electron microscopy and finite element simulation.